1. technology and computing
2. hardware
3. computer networking
4. router

Mobile Ad hoc Networks Working Group
Internet-Draft
Intended status: Standards Track
Expires: January 7, 2016
C. Perkins
Futurewei
S. Ratliff
Idirect
J. Dowdell
Airbus Defence and Space
L. Steenbrink
HAW Hamburg, Dept. Informatik
V. Mercieca
Airbus Defence and Space
July 6, 2015
Ad Hoc On-demand Distance Vector (AODVv2) Routing
draft-ietf-manet-aodvv2-10
Abstract
The revised Ad Hoc On-demand Distance Vector (AODVv2) routing
protocol is intended for use by mobile routers in wireless, multihop
networks. AODVv2 determines unicast routes among AODVv2 routers
within the network in an on-demand fashion, offering rapid
convergence in dynamic topologies.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current InternetDrafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on January 7, 2016.
Copyright Notice
Copyright (c) 2015 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust’s Legal
Provisions Relating to IETF Documents
Perkins, et al.
Expires January 7, 2016
[Page 1]
Internet-Draft
AODVv2
July 2015
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1.
2.
3.
4.
Overview . . . . . . . . . . . . . . . . . . . . .
Terminology . . . . . . . . . . . . . . . . . . . .
Applicability Statement . . . . . . . . . . . . . .
Data Structures . . . . . . . . . . . . . . . . . .
4.1. Interface List . . . . . . . . . . . . . . . .
4.2. Router Client List . . . . . . . . . . . . . .
4.3. Neighbor Table . . . . . . . . . . . . . . . .
4.4. Sequence Numbers . . . . . . . . . . . . . . .
4.5. Multicast Route Message Table . . . . . . . . .
4.6. Route Table Entry . . . . . . . . . . . . . . .
5. Metrics . . . . . . . . . . . . . . . . . . . . . .
5.1. Cost Function . . . . . . . . . . . . . . . . .
5.2. LoopFree Function . . . . . . . . . . . . . . .
5.3. Default Metric Type . . . . . . . . . . . . . .
5.4. Alternate Metric Types . . . . . . . . . . . .
6. AODVv2 Protocol Operations . . . . . . . . . . . .
6.1. Initialization . . . . . . . . . . . . . . . .
6.2. Adjacency Monitoring . . . . . . . . . . . . .
6.3. Message Transmission . . . . . . . . . . . . .
6.4. Route Discovery, Retries and Buffering . . . .
6.5. Processing Received Route Information . . . . .
6.5.1. Evaluating Route Information . . . . . . .
6.5.2. Applying Route Updates . . . . . . . . . .
6.6. Suppressing Redundant Messages . . . . . . . .
6.7. Route Maintenance . . . . . . . . . . . . . . .
6.7.1. Route State . . . . . . . . . . . . . . . .
6.7.2. Reporting Invalid Routes . . . . . . . . .
7. AODVv2 Protocol Messages . . . . . . . . . . . . .
7.1. Route Request (RREQ) Message . . . . . . . . .
7.1.1. RREQ Generation . . . . . . . . . . . . . .
7.1.2. RREQ Reception . . . . . . . . . . . . . .
7.1.3. RREQ Regeneration . . . . . . . . . . . . .
7.2. Route Reply (RREP) Message . . . . . . . . . .
7.2.1. RREP Generation . . . . . . . . . . . . . .
7.2.2. RREP Reception . . . . . . . . . . . . . .
7.2.3. RREP Regeneration . . . . . . . . . . . . .
7.3. Route Reply Acknowledgement (RREP_Ack) Message
7.3.1. RREP_Ack Generation . . . . . . . . . . . .
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7.3.2. RREP_Ack Reception . .
7.4. Route Error (RERR) Message
7.4.1. RERR Generation . . . .
7.4.2. RERR Reception . . . .
7.4.3. RERR Regeneration . . .
8. RFC 5444 Representation . . . .
8.1. RREQ . . . . . . . . . . .
8.1.1. Message Header . . . .
8.1.2. Message TLV Block . . .
8.1.3. Address Block . . . . .
8.1.4. Address Block TLV Block
8.2. RREP . . . . . . . . . . .
8.2.1. Message Header . . . .
8.2.2. Message TLV Block . . .
8.2.3. Address Block . . . . .
8.2.4. Address Block TLV Block
8.3. RREP_Ack . . . . . . . . .
8.3.1. Message Header . . . .
8.3.2. Message TLV Block . . .
8.3.3. Address Block . . . . .
8.3.4. Address Block TLV Block
8.4. RERR . . . . . . . . . . .
8.4.1. Message Header . . . .
8.4.2. Message TLV Block . . .
8.4.3. Address Block . . . . .
8.4.4. Address Block TLV Block
9. Simple Internet Attachment . .
10. Optional Features . . . . . . .
10.1. Expanding Rings Multicast
10.2. Precursor Lists . . . . .
10.3. Intermediate RREP . . . .
10.4. Message Aggregation Delay
11. Configuration . . . . . . . . .
11.1. Timers . . . . . . . . . .
11.2. Protocol Constants . . . .
11.3. Local Settings . . . . . .
11.4. Network-Wide Settings . .
11.5. Optional Feature Settings
12. IANA Considerations . . . . . .
12.1. RFC 5444 Message Types . .
12.2. RFC 5444 Address Block TLV
12.3. MetricType Allocation . .
12.4. AddressType Allocation . .
13. Security Considerations . . . .
14. Acknowledgments . . . . . . . .
15. References . . . . . . . . . .
15.1. Normative References . . .
15.2. Informative References . .
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AODVv2
Appendix A. Features Required of IP . . . . . . . .
Appendix B. Multi-homing Considerations . . . . . .
Appendix C. Router Client Relocation . . . . . . . .
Appendix D. Example Algorithms for AODVv2 Operations
D.1. General Operations . . . . . . . . . . . . .
D.1.1. Check_Route_State . . . . . . . . . . . .
D.1.2. Process_Routing_Info . . . . . . . . . .
D.1.3. Fetch_Route_Table_Entry . . . . . . . . .
D.1.4. Update_Route_Table_Entry . . . . . . . .
D.1.5. Create_Route_Table_Entry . . . . . . . .
D.1.6. LoopFree . . . . . . . . . . . . . . . .
D.1.7. Fetch_Rte_Msg_Table_Entry . . . . . . . .
D.1.8. Update_Rte_Msg_Table . . . . . . . . . .
D.1.9. Build_RFC_5444_Message_Header . . . . . .
D.2. RREQ Operations . . . . . . . . . . . . . . .
D.2.1. Generate_RREQ . . . . . . . . . . . . . .
D.2.2. Receive_RREQ . . . . . . . . . . . . . .
D.2.3. Regenerate_RREQ . . . . . . . . . . . . .
D.3. RREP Operations . . . . . . . . . . . . . . .
D.3.1. Generate_RREP . . . . . . . . . . . . . .
D.3.2. Receive_RREP . . . . . . . . . . . . . .
D.3.3. Regenerate_RREP . . . . . . . . . . . . .
D.4. RREP_Ack Operations . . . . . . . . . . . . .
D.4.1. Generate_RREP_Ack . . . . . . . . . . . .
D.4.2. Receive_RREP_Ack . . . . . . . . . . . .
D.4.3. Timeout_RREP_Ack . . . . . . . . . . . .
D.5. RERR Operations . . . . . . . . . . . . . . .
D.5.1. Generate_RERR . . . . . . . . . . . . . .
D.5.2. Receive_RERR . . . . . . . . . . . . . .
D.5.3. Regenerate_RERR . . . . . . . . . . . . .
Appendix E. AODVv2 Draft Updates . . . . . . . . . .
E.1. Changes between revisions 9 and 10 . . . . .
E.2. Changes between revisions 8 and 9 . . . . . .
E.3. Changes between revisions 7 and 8 . . . . . .
E.4. Changes between revisions 6 and 7 . . . . . .
E.5. Changes between revisions 5 and 6 . . . . . .
E.6. Changes between revisions 4 and 5 . . . . . .
E.7. Changes between revisions 3 and 4 . . . . . .
E.8. Changes between revisions 2 and 3 . . . . . .
Authors’ Addresses . . . . . . . . . . . . . . . . .
1.
July 2015
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Overview
The revised Ad hoc On-demand Distance Vector (AODVv2) routing
protocol [formerly named DYMO] enables on-demand, multihop unicast
routing among AODVv2 routers in mobile ad hoc networks [MANETs]
[RFC2501]. The basic operations of the AODVv2 protocol are route
discovery and route maintenance.
Perkins, et al.
Expires January 7, 2016
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AODVv2
July 2015
Route discovery is performed when an AODVv2 router needs to forward a
packet for one of its clients, but does not have a valid route to the
packet’s destination. AODVv2 routers use Route Request (RREQ) and
Route Reply (RREP) messages to carry route information between the
originator of the route discovery and the target node, establishing a
route to both endpoints on all intermediate routers.
A metric is included in RREQ and RREP messages to represent the cost
of the route to the originator or target of the route discovery.
AODVv2 compares route metrics in a way that ensures loop avoidance.
AODVv2 also uses sequence numbers to assure loop freedom, enabling
identification of stale routing information so that it can be
discarded.
Route maintenance involves monitoring the router’s links and routes
for changes. This includes confirming adjacencies with other AODVv2
routers, issuing Route Error messages if link failures invalidate
routes, extending and enforcing route timeouts, and reacting to
received Route Error messages.
AODVv2 control plane messages use the Generalized MANET Packet/
Message Format defined in [RFC5444] and the parameters in [RFC5498].
AODVv2 defines a set of data elements which map to RFC 5444 Address
Blocks, Address Block TLVs, and Message TLVs.
Security for authentication of AODVv2 routers and encryption of
control messages is dealt with by using the recommendations in
[RFC7182].
2.
Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in
[RFC2119]. In addition, this document uses terminology from
[RFC5444], and defines the following terms:
AddressList
An AODVv2 Data Element (see Table 1).
Adjacency
A bi-directional relationship between neighboring AODVv2 routers
for the purpose of exchanging routing information.
AckReq
An AODVv2 Data Element (see Table 1).
AODVv2 Router
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July 2015
An IP addressable device in the ad hoc network that performs the
AODVv2 protocol operations specified in this document.
CurrentTime
The current time as maintained by the AODVv2 router.
Data Element
A named object used within AODVv2 protocol messages (see Table 1).
Disregard
Ignore for further processing.
Invalid route
A route that cannot be used for forwarding.
MANET
A Mobile Ad Hoc Network as defined in [RFC2501].
MetricType
An AODVv2 Data Element (see Table 1).
MetricTypeList
An AODVv2 Data Element (see Table 1).
Node
An IP addressable device in the ad hoc network. All nodes in this
document are either AODVv2 Routers or Router Clients.
OrigAddr (Originator Address)
An AODVv2 Data Element (see Table 1).
OrigMetric
An AODVv2 Data Element (see Table 1).
OrigNode (Originating Node)
The node that launched the application requiring communication
with the Target Address.
OrigPrefixLen
The prefix length, in bits, associated with OrigAddr.
OrigSeqNum
An AODVv2 Data Element (see Table 1).
PktSource
An AODVv2 Data Element (see Table 1).
PrefixLengthList
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July 2015
An AODVv2 Data Element (see Table 1).
Reactive
A protocol operation is called "reactive" if it is performed only
in reaction to specific events. In this document, "reactive" is
synonymous with "on-demand".
RERR (Route Error)
The AODVv2 message type used to indicate that an AODVv2 router
does not have a route toward one or more particular destinations.
RERR_Gen (RERR Generating Router)
The AODVv2 router generating a Route Error message.
Routable Unicast IP Address
A routable unicast IP address is a unicast IP address that is
scoped sufficiently to be forwarded by a router. Globally-scoped
unicast IP addresses and Unique Local Addresses (ULAs) ([RFC4193])
are examples of routable unicast IP addresses.
Router Client
A node that requires the services of an AODVv2 router.
router is also its own client.
An AODVv2
RREP (Route Reply)
The AODVv2 message type used to reply to a Route Request message.
RREP_Gen (RREP Generating Router)
The AODVv2 router responsible for the Target Node of a Route
Request message, i.e., the router that creates the Route Reply
message.
RREQ (Route Request)
The AODVv2 message type used to discover a route to the Target
Address and distribute information about the route to the
Originator Address.
RREQ_Gen (RREQ Generating Router)
The AODVv2 router that creates the Route Request message on behalf
of the Originating Node to discover a route for Target Address.
RteMsg (Route Message)
A Route Request (RREQ) or Route Reply (RREP) message.
Sequence Number (SeqNum)
One of the sequence numbers maintained by an AODVv2 router to
indicate freshness of route information. Used as an AODVv2 Data
Element (see Table 1).
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SeqNumList
An AODVv2 Data Element (see Table 1).
TargAddr (Target Address)
An AODVv2 Data Element (see Table 1).
Target Node
The node hosting the IP address toward which a route is needed.
TargMetric
An AODVv2 Data Element (see Table 1).
TargPrefixLen
The prefix length, in bits, associated with TargAddr.
TargSeqNum
An AODVv2 Data Element (see Table 1).
Unreachable Address
An address for which a valid route is not known.
Upstream
In the direction from destination to source (from TargAddr to
OrigAddr).
Valid route
A route that can be used for forwarding.
ValidityTime
An AODVv2 Data Element (see Table 1).
This document defines a set of Data Elements in Table 1 which are
used in AODVv2 messages. These data elements contain the message
data which is transferred into RFC 5444 formatted messages
(Section 8) before sending.
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+------------------+------------------------------------------------+
| Data Element
| Meaning
|
+------------------+------------------------------------------------+
| AckReq
| Presence in RREP means acknowledgement is
|
|
| requested from the router with the address
|
|
| indicated
|
| AddressList
| A list of IP addresses
|
| MetricType
| The metric type for a metric value
|
| MetricTypeList
| Metric types associated with routes to
|
|
| addresses in AddressList, used in RERR
|
| msg_hop_limit
| Number of hops the message is allowed to
|
|
| traverse
|
| msg_hop_count
| Number of hops traversed so far by the message |
| OrigMetric
| Metric value associated with the route to
|
|
| OrigAddr
|
| OrigSeqNum
| Sequence number associated with OrigAddr, used |
|
| in RREQ
|
| OrigAddr
| IP address of the Originating Node, the source |
|
| address of the packet triggering route
|
|
| discovery
|
| PktSource
| Source address of a packet triggering a RERR
|
|
| message
|
| PrefixLengthList | A list of routing prefixes associated with
|
|
| addresses in AddressList
|
| SeqNum
| Sequence number, when used in RERR
|
| SeqNumList
| A list of generic sequence numbers associated |
|
| with addresses in an AddressList, used in RERR |
| TargAddr
| IP address of the Target Node, the destination |
|
| address for which a route is requested
|
| TargMetric
| Metric value associated with the route to
|
|
| TargAddr
|
| TargSeqNum
| Sequence number associated with TargAddr, used |
|
| in RREQ (optional) and RREP
|
| ValidityTime
| Length of time a route is offered
|
+------------------+------------------------------------------------+
Table 1: Data Elements
This document uses the notational conventions in Table 2 to simplify
the text.
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+----------------------+--------------------------------------------+
| Notation
| Meaning
|
+----------------------+--------------------------------------------+
| Route[Address]
| A route table entry toward Address
|
| Route[Address].Field | A field in a route table entry toward
|
|
| Address
|
| RteMsg
| Either RREQ or RREP
|
| RteMsg.Field
| A field in either RREQ or RREP
|
| AdvRte
| A route advertised in an incoming RteMsg
|
+----------------------+--------------------------------------------+
Table 2: Notational Conventions
3.
Applicability Statement
The AODVv2 routing protocol is a reactive routing protocol designed
for stub or disconnected mobile ad hoc networks, i.e., non-transit
networks or those not connected to the internet.
AODVv2 handles a wide variety of mobility and traffic patterns by
determining routes on-demand. In networks with a large number of
routers, AODVv2 is best suited for relatively sparse traffic
scenarios where each router forwards packets to a small percentage of
other AODVv2 routers in the network. In this case fewer routes are
needed, and therefore less control traffic is produced.
AODVv2 is well suited to reactive scenarios such as emergency and
disaster relief, where the ability to communicate is more important
than being assured of secure operations. For other ad hoc networking
applications, in which insecure operation could negate the value of
establishing communication paths, it is important for neighboring
AODVv2 nodes to establish security associations with one another.
AODVv2 will not make use of uni-directional links. Route requests
from routers which cannot confirm bidirectional connectivity should
be ignored to avoid persistent packet loss or protocol failures.
AODVv2 is applicable to memory constrained devices, since only a
little routing state is maintained in each AODVv2 router. In
contrast to proactive routing protocols, which maintain routing
information for all destinations within the MANET, AODVv2 routes that
are not needed for forwarding data do not need to be maintained. On
routers unable to store persistent AODVv2 state, recovery can impose
a performance penalty (e.g., in case of AODVv2 router reboot).
AODVv2 supports routers with multiple interfaces, as long as each
interface configured for AODVv2 has its own unicast routable IP
address. Address assignment procedures are out of scope for AODVv2.
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Multi-homing is not supported by AODVv2, and therefore a Router
Client SHOULD NOT be served by more than one AODVv2 router at any one
time. Appendix B contains some notes on this topic.
Although AODVv2 is closely related to AODV [RFC3561], and shares some
features of DSR [RFC4728], AODVv2 is not interoperable with either of
those protocols.
The routing algorithm in AODVv2 may be operated at layers other than
the network layer, using layer-appropriate addresses.
AODVv2 can be configured to perform gateway functions when attached
to the internet. Such a gateway router is referred to as an Internet
AODVv2 Router (IAR) as discussed in Section 9. The IAR will reply to
each route request generated inside the AODVv2 network for an
internet destination as if they were responsible for the target
address, and may advertise the AODVv2 network to the internet using
procedures out of scope for this specification.
4.
Data Structures
4.1.
Interface List
A list of the interfaces supporting AODVv2 should be configured in
the AODVv2_INTERFACES list.
4.2.
Router Client List
An AODVv2 router may provide routing services for its own local
applications and for other non-routing nodes that are directly
reachable via its network interfaces. These nodes, including the
AODVv2 router itself, are referred to as Router Clients.
Each AODVv2 router MUST be configured with information about the IP
addresses of its clients. If a subnet is configured as a Router
Client, the AODVv2 router MUST serve every node in that subnet.
A CLIENT_ADDRESSES list should exist to store information about
Router Clients, with the following information:
RouterClient.IPAddress
The IP address of the client node or subnet that requires routing
services from the AODVv2 router.
RouterClient.PrefixLength
The length, in bits, of the routing prefix associated with the
client IP address or subnet.
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The list of Router Clients for an AODVv2 router is never empty, since
an AODVv2 router is always its own client. The IP Addresses of the
router’s interfaces will appear in the Router Client list.
The router MUST respond to Route Requests for all Router Clients.
the initial state, an AODVv2 router is not required to have
information about the Router Clients of any other AODVv2 router.
In
A Router Client SHOULD NOT be served by more than one AODVv2 router
at any one time. Shifting responsibility for a Router Client to a
different AODVv2 router is discussed in Appendix C.
4.3.
Neighbor Table
A neighbor table MUST be maintained with information about
neighboring AODVv2 routers, including an indication of the state of
the adjacency to the router. Section 6.2 discusses how to monitor
adjacency.
Neighboring routers which cannot confirm adjacency should be marked
as blacklisted. Certain AODVv2 messages received from a blacklisted
router should be ignored. Routers should be blacklisted for a
maximum of MAX_BLACKLIST_TIME, but can be removed from the blacklist
before this time if an indication of adjacency is received.
Neighbor entries should contain:
Neighbor.IPAddress
An IP address of the neighboring router.
Neighbor.State
The state of the adjacency (Confirmed, Unknown, or Blacklisted)
Neighbor.ResetTime
The time at which this router SHOULD no longer be considered
blacklisted. By default this value is calculated at the time the
router is blacklisted and is equal to CurrentTime +
MAX_BLACKLIST_TIME. After this time, the state should be reset to
Unknown. While the neighbor is not marked as blacklisted, this
value SHOULD be set to MAX_TIME.
Before a neighbor is confirmed, any routes learned through that
neighbor are marked as Unconfirmed. When neighbor state is set to
Confirmed, the Unconfirmed routes using the neighbor as a next hop
can transition to Idle state (see Section 6.7.1).
If a neighbor is blacklisted, any valid routes installed which use
that neighbor for their next hop should become Invalid.
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When the link to a neighbor breaks, the neighbor entry should be
removed and all routes using the neighbor as next hop should become
Invalid.
4.4.
Sequence Numbers
Sequence numbers enable AODVv2 routers to determine the temporal
order of route discovery messages, identifying stale routing
information so that it can be discarded. The sequence number
fulfills the same roles as the "Destination Sequence Number" of DSDV
[Perkins94], and the AODV Sequence Number in [RFC3561].
Each AODVv2 router in the network MUST maintain its own sequence
number as a 16-bit unsigned integer. All route messages (Route
Request and Route Reply messages) created by an AODVv2 router include
the router’s sequence number.
If the router has multiple AODVv2 interfaces, it can maintain
different sequence numbers for each interface IP address, but the
router MUST NOT use multiple sequence numbers for any one interface
IP address. All route messages created on behalf of Router Clients
on a particular interface MUST include the sequence number of that
interface’s IP address.
Each AODVv2 router MUST ensure that its sequence number is strictly
increasing. It can ensure this by incrementing the sequence number
by one (1) whenever a route message is created, except when the
sequence number is 65,535 (the maximum value of a 16-bit unsigned
integer), in which case it MUST be reset to one (1). The value zero
(0) is reserved to indicate that the sequence number for an address
is unknown.
A router receiving a route message uses the sequence number to
determine the freshness of the route information in the message in
comparison with any existing information about the same route. If
the sequence number stored in the route table is higher than the
sequence number in the message, the received information is
considered stale and MUST NOT be used to update the route table.
As a consequence, loop freedom is assured.
An AODVv2 router SHOULD maintain its sequence number(s) in persistent
storage. If a sequence number is lost, the router must follow the
procedure in Section 6.1 to safely resume routing operations with a
new sequence number.
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4.5.
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Multicast Route Message Table
A route message (RteMsg) is either a Route Request and Route Reply
message. The Multicast Route Message Table (RteMsg Table) contains
information about previously received multicast route messages, so
that when a route message is received, an AODVv2 router can determine
if the incoming information is redundant, and avoid unnecessary
regeneration of the route message. RREQ messages are usually
multicast. Future extensions to AODVv2 MAY enable RREP messages to
be multicast.
Each entry in the RteMsg Table stores the following information,
copied from the route message:
RteMsg.MessageType
Either RREQ or RREP.
RteMsg.OrigAddr
The IP address of the originating node wishing to send a packet.
RteMsg.OrigPrefixLen
The prefix length associated with OrigAddr.
RteMsg.TargAddr
The IP address of the target node, the destination of the packet.
RteMsg.TargPrefixLen
The prefix length associated with TargAddr.
RteMsg.OrigSeqNum
The sequence number associated with the originator, if present in
RteMsg.
RteMsg.TargSeqNum
The sequence number associated with the target, if present in
RteMsg.
RteMsg.MetricType
The metric type of the route requested.
RteMsg.Metric
The metric value received in the RteMsg.
RteMsg.Timestamp
The last time this entry was updated.
RteMsg.RemoveTime
The time at which this entry MUST be removed.
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Multicast RteMsgs are considered to be comparable if they have the
same MessageType, OrigAddr, TargAddr, and MetricType. The RteMsg
Table is maintained so that no two entries are comparable, i.e., all
entries either have different MessageType, different OrigAddr,
different TargAddr, or different MetricType. See Section 6.6 for
details on updating this table.
Entries in the RteMsg Table MUST be deleted when the sequence number
is no longer valid, i.e., after MAX_SEQNUM_LIFETIME. RemoveTime
should be set when the sequence number of the entry is updated, i.e.,
when OrigSeqNum is updated for a RREQ, and when TargSeqNum is updated
for a RREP. RemoveTime should be set to CurrentTime +
MAX_SEQNUM_LIFETIME. Memory-constrained devices MAY remove the entry
before this time, but the entry should be maintained for at least
RteMsg_ENTRY_TIME after the last Timestamp update in order to account
for long-lived RREQs traversing the network.
4.6.
Route Table Entry
The route table entry is a conceptual data structure.
Implementations MAY use any internal representation that provides
access to the following information:
Route.Address
An address or address prefix of a node.
Route.PrefixLength
The prefix length, in bits, associated with the address. If it is
less than the length of Route.Address, this is a route to the
subnet on which Route.Address resides.
Route.SeqNum
The sequence number associated with Route.Address, obtained from
the last route message that successfully updated this route table
entry.
Route.NextHop
An IP address of the AODVv2 router used for the next hop on the
path toward Route.Address.
Route.NextHopInterface
The interface used to send packets toward Route.Address.
Route.LastUsed
The time this route was last used to forward a packet.
Route.LastSeqNumUpdate
The time the sequence number for this route was last updated.
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Route.ExpirationTime
The time at which this route must be marked as Invalid.
Route.MetricType
The type of metric associated with this route.
Route.Metric
The cost of the route toward Route.Address expressed in units
consistent with Route.MetricType.
Route.State
The last known state (Active, Idle, Invalid, or Unconfirmed) of
the route.
Route.Precursors (optional feature)
A list of upstream neighbors using the route (see Section 10.2).
There are four possible states for an AODVv2 route:
Active
An Active route is in current use for forwarding packets.
Idle
An Idle route has not been used in the last ACTIVE_INTERVAL, but
can still be used for forwarding packets.
Invalid
An Invalid route cannot be used for forwarding packets, but its
sequence number information allows incoming information to be
assessed for freshness.
Unconfirmed
An Unconfirmed route cannot be used for forwarding packets.
a route learned
It is
from a Route Request which has not yet been confirmed as
bidirectional.
Route state changes are detailed in Section 6.7.1.
An AODVv2 route may be offered for a limited time. In this case, the
route is referred to as a timed route. The length of time for which
the route is valid is referred to as validity time, and is included
in messages which advertise the route. The shortened validity time
is reflected in Route.ExpirationTime. If a route is not timed, the
ExpirationTime is MAX_TIME, and the route will become Idle and then
Invalid if it is not used. Invalid routes should be maintained for
their sequence number information.
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Metrics
Metrics measure a cost or quality associated with a route or a link,
e.g., latency, delay, financial cost, energy, etc.
AODVv2 enables the use of multiple metric types. Each metric that
can be used in AODVv2 has a MetricType number. Numbers are allocated
by IANA as specified in [RFC6551] or detailed in Section 12.3. The
default metric type is discussed in Section 5.3. Alternate metrics
are discussed in Section 5.4.
An AODVv2 implementation MAY be configured to use a limited set of
the supported metric types. In the processing described in
Section 7, a "known" MetricType can be interpreted as a configured
MetricType. If a message is received using an unknown or nonconfigured MetricType it MUST be ignored. Since the message will not
be regenerated, other routers which do support the MetricType will
not be able to route through a router which does not support the
MetricType.
For each MetricType, a maximum value is defined, denoted
MAX_METRIC[MetricType]. AODVv2 cannot store routes that cost more
than MAX_METRIC[MetricType].
Metric information reported in incoming route messages describes the
metric as measured by message sender, and does not reflect the cost
of traversing the link to that sender. The receiving router
calculates the cost of the route from its perspective. This cost is
used to determine whether to use incoming information to update an
existing route. If the cost exceeds MAX_METRIC[MetricType], the
route is ignored.
5.1.
Cost Function
This document uses the following notation to represent costs:
o
Cost(L) for link cost
o
Cost(R) for route cost
These functions return the cost of traversing a link or a route.
Cost(L) and Cost(R) for the default metric type are detailed in
Section 5.3. The Cost() functions for other metric types are beyond
the scope of this document.
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LoopFree Function
When comparing an advertised route to an existing route for the same
destination and the same metric type, the metric value should be
examined to ensure that using the advertised route does not create
any routing loops.
The function LoopFree(R1, R2) is defined to verify that a route R2 is
not a part of another route R1. LoopFree returns TRUE if R2 cannot
be a sub-section of the route R1.
An AODVv2 router invokes LoopFree() as part of the process in
Section 6.5.1. The advertised route (AdvRte) is used as parameter
R1, and the stored route (Route) is used as parameter R2.
The LoopFree(R1,R2) function for the default metric type is detailed
in Section 5.3. The LoopFree(R1,R2) functions for other metric types
are beyond the scope of this document.
5.3.
Default Metric Type
AODVv2’s default metric type (DEFAULT_METRIC_TYPE) is HopCount, and
is the only metric described in detail in this document. Alternate
metrics are discussed in Section 5.4.
For the HopCount metric:
o
Cost(L) := 1
o
Cost(R) := Sum (Cost(L) of each link in the route), i.e., the hop
count between the router calculating the cost, and the destination
of the route
o
LoopFree(R1, R2) returns TRUE when the cost of R1 is less than or
equal to the cost of R2, i.e., Cost(R1) <= Cost(R2)
o
MAX_METRIC[HopCount] := MAX_HOPCOUNT
The LoopFree function for the HopCount metric is derived from the
fact that route cost increases with number of hops. When examining
two routes, the route with higher cost may include the route with
lower cost as a sub-section of its route. Therefore, an advertised
route with higher cost than the corresponding stored route could
include the stored route as a sub-section. Replacing the stored
route with the received route could form a routing loop. LoopFree
returns FALSE in this case to indicate that an advertised route with
higher cost is not to be used to update a stored route, even if the
stored route is Invalid.
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MAX_HOPCOUNT is a constant defined in Section 11.2. It MUST be
larger than the AODVv2 network diameter, in order that AODVv2
protocol messages may reach their intended destinations.
5.4.
Alternate Metric Types
Some applications may require metric information other than hop
count. For this reason, AODVv2 enables route selection based on
alternate metric types.
Using non-default metrics in an AODVv2 message requires the inclusion
of the MetricType data element.
Alternate metrics may have different types and ranges, for example
integers or floating point numbers, or restricted subsets thereof.
Therefore the size of the metric field in route messages may vary.
See Section 12.3 for further information on MetricType number
allocation and size.
Metrics might be classified as additive, concave, convex, or
multiplicative as discussed in [RFC6551]. Where Cost and LoopFree
functions can be developed for a metric type, it can be supported by
AODVv2.
AODVv2 can support additive metrics using the Cost(R) and
LoopFree(R1, R2) functions defined for the default metric.
Furthermore, any strictly increasing metric can be supported using
the LoopFree function defined. It is, however, out of the scope of
this document to specify for alternate metrics the correct Cost(L),
Cost(R), and LoopFree() functions. Where possible these should take
into account differences in the link cost in each direction.
6.
AODVv2 Protocol Operations
The AODVv2 protocol’s operations include managing sequence numbers,
monitoring adjacent AODVv2 routers, performing route discovery and
dealing with requests from other routers, processing incoming route
information and updating the route table, suppressing redundant
messages, maintaining the route table and reporting broken routes.
These processes are discussed in detail in the following sections.
6.1.
Initialization
During initialization where the previous sequence number is unknown,
or if the sequence number is lost at any point, an AODVv2 router
resets its sequence number(s) to one (1). However, other AODVv2
routers may still hold sequence number information this router
previously issued. Since sequence number information will be removed
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if there have been no sequence number updates in MAX_SEQNUM_LIFETIME,
the initializing router must wait for MAX_SEQNUM_LIFETIME before it
creates any messages containing its sequence number. It can then be
sure that the information it sends will not be considered stale.
Until MAX_SEQNUM_LIFETIME after its sequence number is reset, the
router SHOULD not create RREQ or RREP messages.
During this wait period, the router can do the following:
o
Process information in a received RREQ or RREP message to learn a
route to the originator or target
o
Send a RREP_Ack
o
Regenerate a received RREQ or RREP
o
Forward data packets to Router Clients, and to other routers, if a
route exists
o
Create, process and regenerate RERR messages
6.2.
Adjacency Monitoring
An adjacency is a bidirectional relationship between neighboring
AODVv2 routers for the purpose of exchanging routing information.
Not every pair of neighboring routers will necessarily form an
adjacency, but AODVv2 routers MUST monitor connectivity to
neighboring AODVv2 routers along potential routes and MUST NOT
establish routes over uni-directional links, since packet losses are
likely to occur and route establishment can fail.
The default approach for monitoring bidirectional connectivity to the
next hop toward OrigAddr is to request acknowledgement of Route Reply
messages. Receipt of an acknowledgement proves that bidirectional
connectivity exists. All AODVv2 routers MUST support this process,
which is explained in Section 7.2 and Section 7.3.
Bidirectionality to the next hop toward TargAddr is confirmed by
receipt of the Route Reply message, since a Route Reply message is a
reply to a Route Request message which previously crossed the link in
the opposite direction.
When routers perform other operations such as those from the list
below, these can be used as additional indications of connectivity:
o
NHDP HELLO Messages [RFC6130]
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o
Route timeout
o
Lower layer triggers, e.g. message reception or link status
notifications
o
TCP timeouts
o
Promiscuous listening
o
Other monitoring mechanisms or heuristics
For example, receipt of a Neighborhood Discovery Protocol HELLO
message with the receiving router listed as a neighbor is a signal of
bidirectional connectivity. In this case, acknowledgement of a RREP
message sent to that neighbor is unnecessary. Similarly, if AODVv2
receives notification of a timeout, this may be due to a
disconnection. The AODVv2 router SHOULD attempt to verify
connectivity by requesting acknowledgement of the next RREP sent to
that neighbor.
The Neighbor Table (Section 4.3) gives the last known state of the
neighbor adjacency, either Confirmed, Unknown, or Blacklisted. Until
bidirectionality is confirmed, the state is Unknown, and
acknowledgement of RREP messages MUST be requested. If the state is
Confirmed, the acknowledgement request is unnecessary. If
bidirectionality cannot be confirmed, the state is Blacklisted.
RREQs received from a blacklisted router, or any router over a link
that is known to be incoming-only, MUST be disregarded.
Neighbor state is updated as follows:
o
If a link to a neighbor is determined to be unidirectional, either
by failure to acknowledge a RREP, or by some other means, the
neighbor MUST be marked as blacklisted.
o
If a notification indicates that there may be a problem with
bidirectionality, and the neighbor state is currently Confirmed,
the state SHOULD be set to Unknown to force acknowledgement of the
next RREP sent to the neighbor.
o
If an indication of bidirectional connectivity is received, the
neighbor state SHOULD be set to Confirmed.
o
If the neighbor state is Blacklisted and the reset time is
reached, the neighbor state SHOULD be reset to Unknown and the
neighbor SHOULD again be allowed to participate in route
discovery.
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If a link to a neighbor is determined to be broken, the neighbor
entry should be removed.
6.3.
Message Transmission
In its default mode of operation, AODVv2 sends [RFC5444] formatted
messages using the parameters for port number and IP protocol
specified in [RFC5498]. Mapping of AODVv2 data elements to RFC 5444
is detailed in Section 8.
Unless otherwise specified, AODVv2 multicast messages are sent to the
link-local multicast address LL-MANET-Routers [RFC5498]. All AODVv2
routers MUST subscribe to LL-MANET-Routers [RFC5498] to receive
AODVv2 messages.
Implementations are free to choose their own heuristics for reducing
multicast overhead. Some methods for doing so are described in
[RFC6621]. AODVv2 does not specify which method should be used to
restrict the set of AODVv2 routers that have the responsibility to
regenerate multicast messages. Note that multicast messages MAY be
sent via unicast. For example, this may occur for certain link-types
(non-broadcast media), for manually configured router adjacencies, or
in order to improve robustness.
When multiple interfaces are available, a node transmitting a
multicast message to LL-MANET-Routers MUST send the message on all
interfaces that have been configured for AODVv2 operation, as given
in the AODVv2_INTERFACES list (Section 4.1). Similarly, AODVv2
routers MUST subscribe to LL-MANET-Routers on all their AODVv2
interfaces.
To avoid congestion, each AODVv2 router’s rate of message generation
(CONTROL_TRAFFIC_LIMIT) SHOULD be limited and administratively
configurable. The implementation is free to choose the algorithm for
limiting messages, including prioritizing messages when approaching
the limit. AODVv2 messages SHOULD be discarded in the following
order: RERR for invalidated routes, RREQ, RREP, RERR for
undeliverable packet, RREP_Ack.
IP packets containing AODVv2 protocol messages SHOULD be given
priority queuing and channel access.
6.4.
Route Discovery, Retries and Buffering
AODVv2’s RREQ and RREP messages are used for route discovery and are
together known as route messages (RteMsgs). The main difference
between the two messages is that, by default, RREQ messages are
multicast to solicit a RREP, whereas RREP is unicast as a response to
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the RREQ. The constants used in this section are defined in
Section 11.
When an AODVv2 router needs to forward a data packet (with source
address OrigAddr and destination address TargAddr) from one of its
Router Clients, it needs a route to the packet’s destination. If no
route exists, the AODVv2 router generates and multicasts a Route
Request message (RREQ) using OrigAddr and TargAddr. The procedure
for this is described in Section 7.1.1. The AODVv2 router is
referred to as RREQ_Gen.
Data packets awaiting a route MAY be buffered by RREQ_Gen.
of data packets can have both positive and negative effects
usually positive). Real-time traffic, voice, and scheduled
may suffer if packets are buffered and subjected to delays,
connection establishment will benefit if packets are queued
route discovery is performed.
Buffering
(albeit
delivery
but TCP
while
The packet buffer is configured with a fixed limited size of
BUFFER_SIZE_PACKETS or BUFFER_SIZE_BYTES. Determining which packets
to discard first when the buffer is full is a matter of policy at
each AODVv2 router. Nodes without sufficient memory available for
buffering SHOULD have buffering disabled by configuring
BUFFER_SIZE_PACKETS := 0 and BUFFER_SIZE_BYTES := 0. This will
affect the latency for launching TCP applications to new
destinations.
RREQ_Gen awaits reception of a Route Reply message (RREP) containing
a route toward TargAddr. A RREQ from TargAddr would also fulfil the
request, if adjacency to the next hop is already confirmed. If a
route to TargAddr is not learned within RREQ_WAIT_TIME, RREQ_Gen MAY
retry the route discovery by generating another RREQ with a new
sequence number. To reduce congestion in a network, repeated
attempts at route discovery for a particular target address SHOULD
utilize a binary exponential backoff, as described in [RFC3561],
where the wait time is doubled for each retry.
The RREQ is received by neighboring AODVv2 routers, and processed and
regenerated as described in Section 7.1. Intermediate routers learn
a potential route to OrigAddr from the RREQ. The router responsible
for TargAddr responds by generating a Route Reply message (RREP) and
sends it back toward RREQ_Gen using the route to OrigAddr learned
from the RREQ. Each intermediate router regenerates the RREP and
unicasts toward OrigAddr.
Links which are not bidirectional cause problems. If a RREP is not
received at an intermediate router, the RREP cannot be regenerated
and will never reach RREQ_Gen. However, since routers monitor
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adjacencies (Section 6.2), the loss of the RREP will cause the last
router which regenerated the RREP to blacklist the router which did
not receive it. When a timeout occurs at RREQ_Gen, a new RREQ may be
regenerated. When the new RREQ arrives again via the blacklisted
router, it will be ignored, and the RREQ should discover a different
path.
Route discovery SHOULD be considered to have failed after
DISCOVERY_ATTEMPTS_MAX and the corresponding wait time for a RREP
response to the final RREQ. After the attempted route discovery has
failed, RREQ_Gen MUST wait at least RREQ_HOLDDOWN_TIME before
attempting another route discovery to the same destination. Any data
packets buffered for TargAddr MUST also be dropped and a Destination
Unreachable ICMP message (Type 3) with a code of 1 (Host Unreachable
Error) SHOULD be delivered to the source of the data packet. The
source may be an application on RREQ_Gen itself, or on a Router
Client with address OrigAddr.
If RREQ_Gen does receive a route message containing a route to
TargAddr within the timeout, it processes the message according to
Section 7. When a valid route is installed, the router can begin
sending the buffered packets. Any retry timers for the corresponding
RREQ SHOULD be cancelled.
During route discovery, all routers on the path learn a route to both
OrigAddr and TargAddr, making the constructed route bidirectional.
6.5.
Processing Received Route Information
All AODVv2 route messages contain a route. A Route Request (RREQ)
includes a route to OrigAddr, and a Route Reply (RREP) contains a
route to TargAddr.
All AODVv2 routers that receive a route message can store the route
contained within it. Incoming information is first checked to verify
that it is both safe to use and offers an improvement to existing
information. This process is explained in Section 6.5.1. The route
table may then be updated according to Section 6.5.2.
In the processes below, RteMsg is used to denote the route message,
AdvRte is used to denote the route contained within it, and Route
denotes a stored routing table entry which matches AdvRte.
AdvRte has the following properties:
o
AdvRte.Address := RteMsg.OrigAddr (in RREQ) or RteMsg.TargAddr (in
RREP)
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o
AdvRte.PrefixLength := RteMsg.OrigPrefixLen (in RREQ) or
RteMsg.TargPrefixLen (in RREP) if included, or if no prefix length
was included in RteMsg, the address length, in bits, of
AdvRte.Address
o
AdvRte.SeqNum := RteMsg.OrigSeqNum (in RREQ) or RteMsg.TargSeqNum
(in RREP)
o
AdvRte.NextHop := IP.SourceAddress (the address of the router from
which the AdvRte was received)
o
AdvRte.MetricType := RteMsg.MetricType if included, or
DEFAULT_METRIC_TYPE if not
o
AdvRte.Metric := RteMsg.Metric
o
AdvRte.Cost := Cost(R) using the cost function associated with the
route’s metric type, where L is the link from the advertising
router, i.e. Cost(R) = AdvRte.Metric + Cost(L) for the default
metric type
o
AdvRte.ValidityTime := RteMsg.ValidityTime, if included
If prefix length information is present, the route describes the
subnet on which the address resides.
6.5.1.
Evaluating Route Information
To determine whether the advertised route should be used to update
the routing table, the incoming route information MUST be processed
as follows:
1.
Search for a routing table entry (Route) matching AdvRte’s
address, prefix length and metric type
*
If no matching route exists, AdvRte SHOULD be used to update
the routing table. Multiple routes to the same destination
may exists with different metric types.
*
If all matching routes have State set to Unconfirmed, AdvRte
SHOULD be used to update the routing table, so that it
contains multiple Unconfirmed routes. If an Unconfirmed route
becomes valid in future, any remaining Unconfirmed routes
which would not offer improvement will be expunged.
*
If a matching route exists with State set to Active, Idle, or
Invalid, continue to Step 2.
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2.
3.
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Compare sequence numbers
*
If AdvRte is more recent (AdvRte.SeqNum > Route.SeqNum),
AdvRte MUST be used to update the routing table.
*
If AdvRte is stale (AdvRte.SeqNum < Route.SeqNum), AdvRte MUST
NOT be used to update the routing table.
*
If the sequence numbers are equal, continue to Step 3.
Check that AdvRte is safe against routing loops (see Section 5.2)
*
If LoopFree(AdvRte, Route) returns FALSE, AdvRte MUST NOT be
used to update the routing table because using the incoming
information might cause a routing loop.
*
If LoopFree(AdvRte, Route) returns TRUE, continue to Step 3.
Compare route costs
*
For some metric types, including the default metric specified
in Section 5.3, the best route is the route with the lowest
metric value. For other metric types, the best route may be
the route with the highest metric.
*
If AdvRte is better, it SHOULD be used to update the routing
table because it offers improvement.
*
If AdvRte is not better (i.e., it is worse or equal) and Route
is valid, AdvRte MUST NOT be used to update the routing table
because it does not offer any improvement.
*
If AdvRte is not better (i.e., it is worse or equal) but Route
is Invalid, AdvRte SHOULD be used to update the routing table
because it can safely repair the existing Invalid route.
If the advertised route SHOULD be used to update the routing table,
the procedure in Section 6.5.2 is followed.
6.5.2.
Applying Route Updates
If AdvRte is from a RREQ message, the next hop neighbor may not be
confirmed as adjacent (see Section 4.3). If Neighbor.State is
Unknown, the route may not be viable, but it MUST be stored to allow
a corresponding RREP to be sent. It SHOULD NOT yet be used to
forward data. Route.State will be set to Unconfirmed to indicate
this. If a valid route already exists for this destination, the
Unconfirmed route should be stored as an additional entry.
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The route update is applied as follows:
1.
If no existing entry in the route table matches AdvRte on
address, prefix length and metric type, continue to Step 3 and
create a new route table entry.
2.
If a matching entry exists:
3.
4.
*
If AdvRte.NextHop is not equal to Route.NextHop, and
AdvRte.NextHop’s Neighbor.State is Unknown and Route.State is
Active or Idle, the current route is valid but the advertised
route may offer improvement, if it can be confirmed. Continue
to Step 3 and create a new route table entry. It can replace
the original route when Neighbor.State is set to Confirmed.
*
If AdvRte.NextHop’s Neighbor.State is Unknown and Route.State
is Invalid, continue to Step 4 and update the existing route
table entry.
*
If AdvRte.NextHop’s Neighbor.State is Confirmed, continue to
Step 4 and update the existing route table entry.
Create a route table entry and initialize as follows:
*
Route.Address := AdvRte.Address
*
Route.PrefixLength := AdvRte.PrefixLength (if included), or
the length, in bits, of Route.Address (32 for IPv4 or 128 for
IPv6)
*
Route.MetricType := AdvRte.MetricType
Update the route table entry as follows:
*
Route.SeqNum := AdvRte.SeqNum
*
Route.NextHop := AdvRte.NextHop
*
Route.NextHopInterface := interface on which RteMsg was
received
*
Route.Metric := AdvRte.Cost
*
Route.LastUsed := CurrentTime
*
Route.LastSeqNumUpdate := CurrentTime
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*
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Route.ExpirationTime := CurrentTime + AdvRte.ValidityTime if a
validity time exists, otherwise MAX_TIME
If a new route was created, or if the existing Route.State is
Invalid or Unconfirmed, update as follows:
*
Route.State := Unconfirmed (if the next hop’s Neighbor.State
is Unknown) or Idle
6.
If an existing route changed from Invalid or Unconfirmed to
become Idle, any matching inferior routes should be expunged.
7.
If this update results in a valid route which fulfills an
outstanding route discovery, the associated timers can be
cancelled and any buffered packets for this route can be
forwarded.
6.6.
Suppressing Redundant Messages
When route messages are flooded in a MANET, an AODVv2 router may
receive multiple similar messages. Regenerating every one of these
gives little additional benefit, and generates unnecessary signaling
traffic and interference.
Each AODVv2 router stores information about recently received route
messages in the AODVv2 Multicast RteMsg Table (Section 4.5).
Received RteMsgs are tested against previously received RteMsgs, and
if determined to be redundant, regeneration can be avoided. Where
necessary, regeneration is performed using the processes in
Section 7.
To determine if a received RREQ is redundant:
1.
2.
Search for an entry in the RteMsg Table with the same
MessageType, OrigAddr, TargAddr, and MetricType
*
If there is none, create an entry to store information about
the received RREQ and regenerate the RREQ.
*
If there is an entry, update the timestamp field, since
comparable RteMsgs are still traversing the network, and
continue to Step 2.
Compare the sequence numbers
*
If the entry has a lower OrigSeqNum than the received RREQ,
update the entry using information from the new RREQ and
regenerate the RREQ.
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*
If the entry has a higher OrigSeqNum than the received RREQ,
do not update the entry and do not regenerate the RREQ.
*
If the entry has the same OrigSeqNum, continue to Step 3.
6.7.
Compare the metric values
*
If the entry has a Metric that is worse than the received
RREQ, update the entry using information from the new RREQ.
*
If the entry has a Metric that is better than the received
RREQ, do not update the entry.
*
In both cases, the RREQ MAY be suppressed to avoid extra
control traffic. However, if the processing of the RREQ
results in an update to the route table, the RREQ MAY be
regenerated to ensure other routers have up-to-date
information.
Route Maintenance
Route maintenance involves monitoring and updating route state,
handling route timeouts and reporting routes that become Invalid.
Before using a route to forward a packet, an AODVv2 router MUST check
the status of the route (Section 6.7.1). If the route is valid, it
MUST be marked as Active and its LastUsed timestamp MUST be updated,
before forwarding the packet to the route’s next hop. If there is no
valid route, this MUST be reported to the packet’s source (see
Section 6.7.2).
6.7.1.
Route State
During normal operation, AODVv2 does not require any explicit
timeouts to manage the lifetime of a route. At any time, any route
table entry can be examined and updated according to the rules below.
Route state should be checked before packet forwarding and before any
operation based on route state.
The four possible states for an AODVv2 route are Active, Idle,
Invalid, and Unconfirmed, as defined in Section 4.6.
Active
If an Active route is not timed (i.e., its ExpirationTime is
MAX_TIME), it becomes Idle if not used within ACTIVE_INTERVAL. A
timed route (i.e., a route with ExpirationTime not equal to
MAX_TIME) remains Active until its expiration time, after which it
MAY either be expunged or marked as Invalid.
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Idle
An Idle route becomes Active if it is used to forward a packet.
If not used, an Idle route remains idle for MAX_IDLETIME before
becoming an Invalid route.
Invalid
An Invalid route MAY be maintained until MAX_SEQNUM_LIFETIME after
the last sequence number update. This allows incoming information
to be assessed for freshness. After this time it should be
expunged.
Unconfirmed
An Unconfirmed route becomes Idle when adjacency with the next hop
router is confirmed, or will be expunged if the neighbor is
blacklisted, or at MAX_SEQNUM_LIFETIME after the last sequence
number update.
In all cases, if the time since the route’s last sequence number
update exceeds MAX_SEQNUM_LIFETIME, the sequence number must be
removed from the route. If the route is Invalid or Unconfirmed at
this time, it MUST be expunged. Active and Idle routes can continue
to be used to forward packets. The removal of the sequence number is
required to ensure that any AODVv2 routers following the
initialization procedure can safely begin routing functions using a
new sequence number.
Appendix D.1.1 contains an algorithmic representation of this timeout
behavior.
Routes can become Invalid before a timeout occurs:
o
If a link breaks, all routes using that link as the next hop MUST
immediately be marked as Invalid.
o
If a Route Error (RERR) message containing the route is received
from the route’s next hop, the route MUST immediately be marked as
Invalid.
When an Unconfirmed route is set as Idle as a result of the adjacency
with Route.NextHop being Confirmed (see Section 4.3), any inferior
matching routes MUST be expunged.
Memory constrained devices MAY choose to expunge routes from the
AODVv2 route table before their expiration time, but MUST adhere to
the following rules:
o
An Active route MUST NOT be expunged.
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o
An Idle route SHOULD NOT be expunged.
o
Any Invalid route MAY be expunged; least recently used Invalid
routes SHOULD be expunged first.
o
An Unconfirmed route MUST NOT be expunged if it was installed
within the last RREQ_WAIT_TIME. Otherwise, it MAY be expunged.
6.7.2.
Reporting Invalid Routes
When an Active route becomes Invalid as a result of a broken link or
a received Route Error (RERR) message, other routers should be
informed by sending a RERR message containing details of the
invalidated route.
A RERR message should also be sent when an AODVv2 router receives a
packet to forward on behalf of another router but does not have a
valid route for the destination of the packet. This packet may be a
data packet or, in rare cases, a RREP message, if the route to the
request originator has been lost. The packet or message triggering
the RERR MUST be discarded.
Generation of a RERR message is described in Section 7.4.1.
7.
AODVv2 Protocol Messages
AODVv2 defines four message types: Route Request (RREQ), Route Reply
(RREP), Route Reply Acknowledgement (RREP_Ack), and Route Error
(RERR).
Each AODVv2 message is defined as a set of data elements. Rules for
the generation, reception and regeneration of each message type are
described in the following sections. Section 8 discusses how the
data elements map to RFC 5444 Message TLVs, Address Blocks, and
Address TLVs.
7.1.
Route Request (RREQ) Message
Route Request messages are used in route discovery operations to
request a route to a specified target address. RREQ messages have
the following general structure:
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+-----------------------------------------------------------------+
|
msg_hop_limit, (optional) msg_hop_count
|
+-----------------------------------------------------------------+
|
AddressList
|
+-----------------------------------------------------------------+
|
PrefixLengthList (optional)
|
+-----------------------------------------------------------------+
|
OrigSeqNum, (optional) TargSeqNum
|
+-----------------------------------------------------------------+
|
MetricType (optional)
|
+-----------------------------------------------------------------+
|
OrigMetric
|
+-----------------------------------------------------------------+
|
ValidityTime (optional)
|
+-----------------------------------------------------------------+
Figure 1: RREQ message structure
RREQ Data Elements
msg_hop_limit
The remaining number of hops allowed for dissemination of the
RREQ message.
msg_hop_count
The number of hops already traversed during dissemination of
the RREQ message.
AddressList
Contains OrigAddr and TargAddr, the source and destination
addresses of the packet for which a route is requested.
OrigAddr and TargAddr MUST be routable unicast addresses.
PrefixLengthList
Contains OrigPrefixLen, i.e., the length, in bits, of the
prefix associated with OrigAddr. If omitted, the prefix length
is equal to OrigAddr’s address length in bits. If OrigAddr
resides on a subnet configured as a Router Client, the prefix
length represents the number of bits in the subnet mask.
OrigSeqNum
The sequence number associated with OrigAddr.
TargSeqNum
A sequence number associated with TargAddr. This may be
included if an Invalid route exists to the target. This is
useful for the optional Intermediate RREP feature (see
Section 10.3).
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MetricType
The type of metric associated with OrigMetric. This element
can be omitted if the default metric type is used.
OrigMetric
The metric associated with the route to OrigAddr, as measured
by the sender of the message.
ValidityTime
The length of time that the message sender is willing to offer
a route toward OrigAddr. Omitted if no time limit is imposed.
7.1.1.
RREQ Generation
A RREQ is generated when a packet needs to be forwarded for a Router
Client, and no valid route currently exists for the packet’s
destination.
Before creating a RREQ, the router should check if a RREQ has
recently been sent for the requested destination. If so, and the
wait time for a reply has not yet been reached, the router should
continue to await a response without generating a new RREQ. If the
timeout has been reached, a new RREQ may be generated. If buffering
is configured, the incoming packet SHOULD be buffered until the route
discovery is completed.
If the limit for the rate of AODVv2 control message generation has
been reached, no message should be generated.
To generate the RREQ, the router (referred to as RREQ_Gen) follows
this procedure:
1.
Set msg_hop_limit := MAX_HOPCOUNT
2.
Set msg_hop_count := 0, if including it
3.
Set AddressList := {OrigAddr, TargAddr}
4.
For the PrefixLengthList:
5.
*
If OrigAddr resides on a Router Client subnet, set
PrefixLengthList := {OrigPrefixLen, null}.
*
Otherwise, omit PrefixLengthList.
For OrigSeqNum:
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*
Increment the SeqNum associated with OrigAddr as specified in
Section 4.4.
*
Set OrigSeqNum := SeqNum.
For TargSeqNum:
*
If an Invalid route exists matching TargAddr using longest
prefix matching and has a valid sequence number, set
TargSeqNum := route’s sequence number.
*
If no Invalid route exists matching TargAddr, or the route
doesn’t have a sequence number, omit TargSeqNum.
7.
Include the MetricType data element if requesting a route for a
non-default metric type, and set the type accordingly
8.
Set OrigMetric := Route[OrigAddr].Metric
9.
Include the ValidityTime data element if advertising that the
route to OrigAddr via this router is offered for a limited time,
and set ValidityTime accordingly
This AODVv2 message is used to create a corresponding RFC 5444
message (see Section 8) which is multicast, by default, to LL-MANETRouters on all interfaces configured for AODVv2 operation.
7.1.2.
RREQ Reception
Upon receiving a RREQ, an AODVv2 router performs the following steps:
1.
2.
If the sender is blacklisted (Section 4.3), check the entry’s
reset time
*
If CurrentTime < Remove Time, ignore this RREQ for further
processing.
*
If CurrentTime >= Remove Time, reset the neighbor state to
Unknown and continue to Step 2.
Verify that the message hop count, if included, hasn’t exceeded
MAX_HOPCOUNT
*
3.
If so, ignore this RREQ for further processing.
Verify that the message contains the required data elements:
msg_hop_limit, OrigAddr, TargAddr, OrigSeqNum, and OrigMetric,
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and that OrigAddr and TargAddr are valid addresses (routable and
unicast)
*
4.
If not, ignore this RREQ for further processing.
If the MetricType data element is present, check that the metric
type is known
*
5.
If not, ignore this RREQ for further processing.
Verify that the cost of the advertised route will not exceed the
maximum allowed metric value for the metric type (Metric <=
MAX_METRIC[MetricType] - Cost(L))
*
If it will, ignore this RREQ for further processing.
6.
Process the route to OrigAddr as specified in Section 6.5.1
7.
Check if the message is redundant by comparing to entries in the
RteMsg table (Section 6.6)
8.
7.1.3.
*
If redundant, ignore this RREQ for further processing.
*
If not redundant, save the information in the RteMsg table to
identify future duplicates and continue processing.
Check if the TargAddr belongs to one of the Router Clients
*
If so, generate a RREP as specified in Section 7.2.1.
*
If not, continue to RREQ regeneration.
RREQ Regeneration
By regenerating a RREQ, a router advertises that it will forward
packets to the OrigAddr contained in the RREQ according to the
information enclosed. The router MAY choose not to regenerate the
RREQ, though this could decrease connectivity in the network or
result in non-optimal paths. The full set of circumstances under
which a router may avoid regenerating a RREQ are not declared in this
document, though examples include the router being heavily loaded or
low on energy and therefore unwilling to advertise routing capability
for more traffic.
The RREQ should not be regenerated if the limit for the rate of
AODVv2 control message generation has been reached.
The procedure for RREQ regeneration is as follows:
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1.
Set msg_hop_limit := received msg_hop_limit - 1
2.
If msg_hop_limit is now zero, do not continue the regeneration
process
3.
Set msg_hop_count := received msg_hop_count + 1, if included,
otherwise omit msg_hop_count
4.
Set AddressList, PrefixLengthList, sequence numbers and
MetricType to the values in the received RREQ
5.
Set OrigMetric := Route[OrigAddr].Metric
6.
If the received RREQ contains a ValidityTime, or if the
regenerating router wishes to limit the time that it offers a
route to OrigAddr, the regenerated RREQ MUST include a
ValidityTime data element
*
The ValidityTime is either the ValidityTime the previous
AODVv2 router specified, or the ValidityTime this router
wishes to impose, whichever is lower.
This AODVv2 message is used to create a corresponding RFC 5444
message (see Section 8) which is multicast, by default, to LL-MANETRouters on all interfaces configured for AODVv2 operation. However,
the regenerated RREQ can be unicast to the next hop address of the
route toward TargAddr, if known.
7.2.
Route Reply (RREP) Message
A Route Reply message is sent in response to a Route Request message
and offers a route to the Target Address in the RREQ.
The RREP is sent by unicast to the next hop router on the route to
OrigAddr, if there is a Confirmed entry in the Neighbor Table for the
next hop. Otherwise, the RREP is sent multicast to LL-MANET-Routers,
including the AckReq data element in the message to indicate the
intended next hop address and request acknowledgement to confirm the
neighbor adjacency.
RREP messages have the following general structure:
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+-----------------------------------------------------------------+
|
msg_hop_limit, (optional) msg_hop_count
|
+-----------------------------------------------------------------+
|
AckReq (optional)
|
+-----------------------------------------------------------------+
|
AddressList
|
+-----------------------------------------------------------------+
|
PrefixLengthList (optional)
|
+-----------------------------------------------------------------+
|
TargSeqNum
|
+-----------------------------------------------------------------+
|
MetricType (optional)
|
+-----------------------------------------------------------------+
|
TargMetric
|
+-----------------------------------------------------------------+
|
ValidityTime (optional)
|
+-----------------------------------------------------------------+
Figure 2: RREP message structure
RREP Data Elements
msg_hop_limit
The remaining number of hops allowed for dissemination of the
RREP message.
msg_hop_count
The number of hops already traversed during dissemination of
the RREP message.
AckReq
The address of the intended next hop of the RREP. This data
element is used when the RREP is multicast because the next hop
toward OrigAddr is a neighbor with Unknown state. It indicates
that an acknowledgement to the RREP is requested by the sender
from the intended next hop (see Section 6.2).
AddressList
Contains OrigAddr and TargAddr, the source and destination
addresses of the packet for which a route is requested.
OrigAddr and TargAddr MUST be routable unicast addresses.
PrefixLengthList
Contains TargPrefixLen, i.e., the length, in bits, of the
prefix associated with TargAddr. If omitted, the prefix length
is equal to TargAddr’s address length, in bits. If TargAddr
resides on a subnet configured as a Router Client, the prefix
length represents the number of bits in the subnet mask.
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TargSeqNum
The sequence number associated with TargAddr.
MetricType
The type of metric associated with TargMetric. This element
can be omitted if the default metric type is used.
TargMetric
The metric associated with the route to TargAddr, as seen from
the sender of the message.
ValidityTime
The length of time that the message sender is willing to offer
a route toward TargAddr. Omitted if no time limit is imposed.
7.2.1.
RREP Generation
A RREP is generated when a RREQ arrives for one of the AODVv2
router’s Router Clients.
Before creating a RREP, the router should check if the corresponding
RREQ is redundant, i.e., a response has already been generated, or if
the limit for the rate of AODVv2 control message generation has been
reached. If so, the RREP should not be created.
If the next hop neighbor on the route to OrigAddr is not yet
confirmed as adjacent (as described in Section 6.2), the RREP MUST
include an AckReq data element including the intended next hop
address, in order to perform adjacency monitoring. If the adjacency
is already confirmed, it can be omitted. The AckReq data element
indicates that an acknowledgement to the RREP is requested from the
intended next hop router in the form of a Route Reply Acknowledgement
(RREP_Ack).
Implementations may allow a number of retries of the RREP if an
acknowledgement is not received within RREP_Ack_SENT_TIMEOUT,
doubling the timeout with each retry, up to a maximum of
RREP_RETRIES, using the same exponential backoff described in
Section 6.4 for RREQ retries. Adjacency confirmation MUST be
considered to have failed after the wait time for a RREP_Ack response
to the final RREP. The next hop router MUST be marked as blacklisted
(Section 4.3), and any installed routes with next hop set to the
newly blacklisted router should become Invalid.
To generate the RREP, the router (also referred to as RREP_Gen)
follows this procedure:
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1.
Set msg_hop_limit := msg_hop_count from the received RREQ
message, if it was included, or MAX_HOPCOUNT if it was not
included
2.
Set msg_hop_count := 0, if including it
3.
If adjacency with the next hop toward OrigAddr is not already
confirmed, include the AckReq data element with the address of
the intended next hop router
4.
Set Address List := {OrigAddr, TargAddr}
5.
For the PrefixLengthList:
6.
*
If TargAddr resides on a Router Client subnet, set
PrefixLengthList := {null, TargPrefixLen}.
*
Otherwise, omit PrefixLengthList.
For the TargSeqNum:
*
Increment the SeqNum associated with TargAddr as specified in
Section 4.4.
*
Set TargSeqNum := SeqNum.
7.
Include the MetricType data element if the route requested is for
a non-default metric type, and set the type accordingly
8.
Set TargMetric := Route[TargAddr].Metric
9.
Include the ValidityTime data element if advertising that the
route to TargAddr via this router is offered for a limited time,
and set ValidityTime accordingly
This AODVv2 message is used to create a corresponding RFC 5444
message (see Section 8). If there is a Confirmed entry in the
Neighbor Table for the next hop router on the route to OrigAddr, the
RREP is sent by unicast to the next hop. Otherwise, the RREP is sent
multicast to LL-MANET-Routers.
7.2.2.
RREP Reception
Upon receiving a RREP, an AODVv2 router performs the following steps:
1.
If the sender is blacklisted (Section 4.3), but the RREP answers
a recently sent RREQ, the sender state should be set to
Confirmed since a RREP is an indication of adjacency
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2.
7.
If it will, ignore this RREP for further processing.
If the AckReq data element is present, check the intended
recipient of the received RREP
*
If the receiving router is the intended recipient, send an
acknowledgement as specified in Section 7.3 and continue
processing.
*
If the receiving router is not the intended recipient, ignore
this RREP for further processing.
Process the route to TargAddr as specified in Section 6.5.1
*
8.
If not, ignore this RREP for further processing.
Verify that the cost of the advertised route will not exceed the
maximum allowed metric value for the metric type (Metric <=
MAX_METRIC[MetricType] - Cost(L))
*
6.
If not, ignore this RREP for further processing.
If the MetricType data element is present, check that the metric
type is known
*
5.
If so, ignore this RREQ for further processing.
Verify that the message contains the required data elements:
msg_hop_limit, OrigAddr, TargAddr, TargSeqNum, and TargMetric,
and that OrigAddr and TargAddr are valid addresses (routable and
unicast)
*
4.
July 2015
Verify that the message hop count, if included, hasn’t exceeded
MAX_HOPCOUNT
*
3.
AODVv2
If the route to TargAddr fulfills a previously sent RREQ, any
associated timeouts will be cancelled and buffered packets
will be forwarded to TargAddr, but processing continues to
Step 8.
Check if the message is redundant by comparing to entries in the
RteMsg table (Section 6.6)
*
If redundant, ignore this RREP for further processing.
*
If not redundant, save the information in the RteMsg table to
identify future redundant RREP messages and continue
processing.
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9.
7.2.3.
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Check if the OrigAddr belongs to one of the Router Clients
*
10.
AODVv2
If so, no further processing is necessary.
Check if a valid (Active or Idle) or Unconfirmed route exists to
OrigAddr
*
If so, continue to RREP regeneration.
*
If not, a Route Error message SHOULD be transmitted to
TargAddr according to Section 7.4.1 and the RREP should be
discarded and not regenerated.
RREP Regeneration
A received Route Reply message is regenerated toward OrigAddr.
Unless the router is prepared to advertise the route contained within
the received RREP, it halts processing. By regenerating a RREP, a
router advertises that it will forward packets to TargAddr according
to the information enclosed. The router MAY choose not to regenerate
the RREP, in the same way it may choose not to regenerate a RREQ (see
Section 7.1.3), though this could decrease connectivity in the
network or result in non-optimal paths.
The RREP should not be regenerated if the limit for the rate of
AODVv2 control message generation has been reached.
If the next hop neighbor on the route to OrigAddr is not yet
confirmed as adjacent (as described in Section 6.2), the RREP MUST
include an AckReq data element including the intended next hop
address, in order to perform adjacency monitoring. If the adjacency
is already confirmed, the AckReq data element can be omitted. The
AckReq data element indicates that an acknowledgement to the RREP is
requested in the form of a Route Reply Acknowledgement (RREP_Ack)
from the intended next hop router.
The procedure for RREP regeneration is as follows:
1.
Set msg_hop_limit := received msg_hop_limit - 1
2.
If msg_hop_limit is now zero, do not continue the regeneration
process
3.
Set msg_hop_count := received msg_hop_count + 1, if it was
included, otherwise omit msg_hop_count
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4.
If an adjacency with the next hop toward OrigAddr is not already
confirmed, include the AckReq data element with the address of
the intended next hop router
5.
Set AddressList, PrefixLengthList, TargSeqNum and MetricType to
the values in the received RREP
6.
Set TargMetric := Route[TargAddr].Metric
7.
If the received RREP contains a ValidityTime, or if the
regenerating router wishes to limit the time that it will offer a
route to TargAddr, the regenerated RREP MUST include a
ValidityTime data element
*
The ValidityTime is either the ValidityTime the previous
AODVv2 router specified, or the ValidityTime this router
wishes to impose, whichever is lower.
This AODVv2 message is used to create a corresponding RFC 5444
message (see Section 8). If there is a Confirmed entry in the
Neighbor Table for the next hop router on the route to OrigAddr, the
RREP is sent by unicast to the next hop. Otherwise, the RREP is sent
multicast to LL-MANET-Routers.
7.3.
Route Reply Acknowledgement (RREP_Ack) Message
The Route Reply Acknowledgement MUST be sent in response to a
received Route Reply which includes an AckReq data element with an
address matching one of the receiving router’s IP addresses. When
the RREP_Ack message is received, it confirms the adjacency between
the two routers. The RREP_Ack has no data elements.
7.3.1.
RREP_Ack Generation
A RREP_Ack MUST be generated when a received RREP includes the AckReq
data element with the address of the receiving router. The RREP_Ack
should not be generated if the limit for the rate of AODVv2 control
message generation has been reached.
There are no data elements in a RREP_Ack. The RFC 5444
representation is discussed in Section 8. The RREP_Ack is unicast,
by default, to the IP address of the router that requested it.
7.3.2.
RREP_Ack Reception
Upon receiving a RREP_Ack, an AODVv2 router performs the following
steps:
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1.
If a RREP_Ack message was expected from the IP source address of
the RREP_Ack, the router cancels any associated timeouts
2.
If the RREP_Ack was expected, ensure the router sending the
RREP_Ack is marked with state Confirmed in the Neighbor
Table (Section 4.3)
7.4.
Route Error (RERR) Message
A Route Error message is generated by an AODVv2 router to notify
other AODVv2 routers of routes that are no longer available. A RERR
message has the following general structure:
+-----------------------------------------------------------------+
|
msg_hop_limit
|
+-----------------------------------------------------------------+
|
PktSource (optional)
|
+-----------------------------------------------------------------+
|
AddressList
|
+-----------------------------------------------------------------+
|
PrefixLengthList (optional)
|
+-----------------------------------------------------------------+
|
SeqNumList (optional)
|
+-----------------------------------------------------------------+
|
MetricTypeList (optional)
|
+-----------------------------------------------------------------+
Figure 3: RERR message structure
RERR Data Elements
msg_hop_limit
The remaining number of hops allowed for dissemination of the
RERR message.
PktSource
The source IP address of the packet triggering the RERR. If
the RERR is triggered by a broken link, the PktSource data
element is not required.
AddressList
The addresses of the routes no longer available through
RERR_Gen.
PrefixLengthList
The prefix lengths, in bits, associated with the routes no
longer available through RERR_Gen, indicating whether a route
represents a single device or a subnet.
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SeqNumList
The sequence numbers of the routes no longer available through
RERR_Gen (where known).
MetricTypeList
The types of metric associated with the routes no longer
available through RERR_Gen. This element can be omitted if all
routes use the default metric type.
7.4.1.
RERR Generation
A RERR is generated when an AODVv2 router (also referred to as
RERR_Gen) needs to report that a destination is no longer reachable.
There are two events that cause this response:
o
If a packet arrives that cannot be forwarded because no valid
route exists for its destination, the RERR generated MUST contain
the PktSource data element and will contain only one unreachable
address. The contents of PktSource and AddressList depend on the
packet that triggered the RERR:
*
If the packet is a data packet forwarded by another AODVv2
router, PktSource is set to the source IP address of the
packet, and the AddressList contains the destination IP address
of the packet.
*
If the packet contains a RREP message and the route to OrigAddr
has been lost, PktSource is set to the TargAddr of the RREP,
and the AddressList contains the OrigAddr from the RREP.
The prefix length and sequence number MAY be included if known
from an Invalid route entry to the destination of the packet. The
MetricTypeList MAY also be included if a MetricType can be
determined from the packet itself, or if an Invalid route exists
for the packet’s destination and the metric type is not
DEFAULT_METRIC_TYPE.
RERR_Gen MUST discard the packet or message that triggered
generation of the RERR.
In order to avoid flooding the network with RERR messages when a
stream of packets to an unreachable address arrives, an AODVv2
router SHOULD determine whether a RERR has recently been sent with
the same unreachable address and PktSource, and SHOULD avoid
creating duplicate RERR messages.
o
When a link breaks, multiple routes may become Invalid, and the
RERR generated MAY contain multiple unreachable addresses. If the
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message contents would cause the MTU to be exceeded, multiple RERR
messages must be sent. The RERR MUST include the MetricTypeList
data element when it contains routes which do not use the
DEFAULT_METRIC_TYPE. The PktSource data element is omitted.
All previously Active routes that used the broken link MUST be
reported. The AddressList, PrefixLengthList, SeqNumList, and
MetricTypeList will contain entries for each route which has
become Invalid.
A RERR message is only sent if an Active route becomes Invalid,
though an AODVv2 router can also include Idle routes that become
Invalid if the configuration parameter ENABLE_IDLE_IN_RERR is set
(see Section 11.3).
Incidentally, if an AODVv2 router receives an ICMP error packet to or
from the address of one of its Router Clients, it simply forwards the
ICMP packet in the same way as any other data packet, and will not
generate any RERR message based on the contents of the ICMP packet.
The RERR should not be generated if the limit for the rate of AODVv2
control message generation has been reached.
To generate the RERR, the router follows this procedure:
1.
Set msg_hop_limit := MAX_HOPCOUNT
2.
If necessary, include the PktSource data element and set the
value to the source address of the packet triggering the RERR
3.
For each route that needs to be reported, while respecting the
interface MTU:
4.
*
Insert the route address into the AddressList.
*
Insert the prefix length into PrefixLengthList, if known and
not equal to the address length.
*
Insert the sequence number into SeqNumList, if known.
*
Insert the metric type into MetricTypeList, if known and not
equal to DEFAULT_METRIC_TYPE.
If interface MTU would be exceeded, create additional RERR
messages
The AODVv2 message is used to create a corresponding RFC 5444 message
(see Section 8).
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If the RERR is sent in response to an undeliverable packet or
message, it SHOULD be sent unicast to the next hop on the route to
PktSource, or alternatively it MUST be multicast to LL-MANET-Routers.
If the RERR is sent in response to a broken link, the RERR is, by
default, multicast to LL-MANET-Routers.
If the optional precursor lists feature (see Section 10.2) is
enabled, the RERR is unicast to the precursors of the routes being
reported.
7.4.2.
RERR Reception
Upon receiving a RERR, an AODVv2 router performs the following steps:
1.
Verify that the message contains the required data elements:
msg_hop_limit and at least one unreachable address
*
2.
If not, ignore this RREP for further processing.
For each address in the AddressList, check that:
*
The address is valid (routable and unicast)
*
The MetricType, if present, is known (assume
DEFAULT_METRIC_TYPE if not present)
*
There is a valid route with the same MetricType matching the
address using longest prefix matching
*
Either the route’s next hop is the sender of the RERR and
route’s next hop interface is the interface on which the RERR
was received, or PktSource is present in the RERR and is a
Router Client address
*
The unreachable address’ sequence number is either unknown, or
is greater than the route’s sequence number
If any of the above are false, the route does not need to be made
Invalid and the unreachable address does not need to be
advertised in a regenerated RERR.
If all of the above are true:
*
If the route’s prefix length is the same as the unreachable
address’ prefix length, set the route state to Invalid, and
note that the route should be advertised in a regenerated
RERR.
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*
If the prefix length is shorter than the original route, the
route MUST be expunged from the routing table, since it is a
sub-route of the larger route which is reported to be Invalid.
*
If the prefix length is different, create a new route with the
unreachable address, and its prefix and sequence number, set
the state to Invalid, and note that the route should be
advertised in a regenerated RERR.
*
Update the sequence number on the stored route, if the
reported sequence number is greater.
3.
If PktSource is included and is a Router Client, do not
regenerate the RERR.
4.
Check if there are unreachable addresses which need to be
advertised in a regenerated RERR
*
If so, regenerate the RERR as detailed in Section 7.4.3.
*
If not, take no further action.
7.4.3.
RERR Regeneration
The RERR should not be generated if the limit for the rate of AODVv2
control message generation has been reached.
The procedure for RERR regeneration is as follows:
1.
Set msg_hop_limit := received msg_hop_limit - 1
2.
If msg_hop_limit is now zero, do not continue the regeneration
process
3.
If the PktSource data element was included in the original RERR,
copy it into the regenerated RERR
4.
For each route that needs to be reported, while respecting the
interface MTU:
*
Insert the unreachable address into the AddressList.
*
Insert the prefix length into PrefixLengthList, if known and
not equal to the address length.
*
Insert the sequence number into SeqNumList, if known.
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*
5.
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Insert the MetricType into MetricTypeList if known, and not
equal to DEFAULT_METRIC_TYPE.
If interface MTU would be exceeded, create additional RERR
messages
The AODVv2 message is used to create a corresponding RFC 5444 message
(see Section 8). If the RERR contains the PktSource data element,
the regenerated RERR SHOULD be sent unicast to the next hop on the
route to PktSource, or alternatively it MUST be multicast to LLMANET-Routers. If the RERR is sent in response to a broken link, the
RERR is, by default, multicast to LL-MANET-Routers.
8.
RFC 5444 Representation
AODVv2 specifies that all control plane messages between routers
SHOULD use the Generalized Mobile Ad Hoc Network Packet/Message
Format [RFC5444], and therefore AODVv2 defines route messages
comprising data elements that map to message elements in RFC 5444.
RFC 5444 provides a multiplexed transport for multiple protocols. An
RFC 5444 multiplexer may choose to optimize the content of certain
message elements to reduce control plane overhead.
A brief summary of the RFC 5444 format:
1.
A packet contains zero or more messages
2.
A message contains a Message Header, one Message TLV Block, zero
or more Address Blocks, and one Address Block TLV Block per
Address Block
3.
The Message TLV Block MAY contain zero or more Message TLVs
4.
An Address Block TLV Block MAY include zero or more Address Block
TLVs
5.
Each TLV value in an Address Block TLV Block can be associated
with all of the addresses, a contiguous set of addresses, or a
single address in the Address Block
AODVv2 does not require access to the RFC 5444 packet header.
In the message header, AODVv2 uses <msg-hop-limit>, <msg-hop-count>,
<msg-type> and <msg-addr-length>. <msg-addr-length> indicates the
length of any addresses in the message (using <msg-addr-length> :=
address length in octets - 1, i.e. 3 for IPv4 and 15 for IPv6).
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Each address included in the Address Block is identified as OrigAddr,
TargAddr, PktSource, or Unreachable Address by including an
ADDRESS_TYPE TLV in the Address Block TLV Block.
The addresses in an Address Block may appear in any order, and values
in a TLV in the Address Block TLV Block must be associated with the
correct address in the Address Block. To indicate which value is
associated with each address, the AODVv2 message representation uses
lists where the order of the addresses in the AODVv2 AddressList data
element matches the order of values in other list-based data
elements, e.g., the order of SeqNums in the SeqNumList in a RERR.
The following sections show how AODVv2 data elements are represented
in RFC 5444 messages. See Section 12 for more information about the
Message TLVs and Address Block TLVs AODVv2 defines, and the type
numbers allocated.
Where the extension type of a TLV is set to zero, this is the default
RFC 5444 value and the extension type will not be included in the
message.
8.1.
8.1.1.
RREQ
Message Header
+---------------+-----------------+---------------------------------+
| Data Element | Header Field
| Value
|
+---------------+-----------------+---------------------------------+
| None
| <msg-type>
| RREQ
|
| msg_hop_limit | <msg-hop-limit> | MAX_HOPCOUNT
|
| msg_hop_count | <msg-hop-count> | Number of hops traversed so far |
|
|
| by the message.
|
+---------------+-----------------+---------------------------------+
8.1.2.
Message TLV Block
A RREQ contains no Message TLVs.
8.1.3.
Address Block
A RREQ contains two Addresses, OrigAddr and TargAddr, and each
address has an associated prefix length. If the prefix length has
not been included in the AODVv2 message, it is equal to the address
length in bits.
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+-------------------------+------------------------------+
| Data Elements
| Address Block
|
+-------------------------+------------------------------+
| OrigAddr/OrigPrefixLen | <address> + <prefix-length> |
| TargAddr/TargPrefixLen | <address> + <prefix-length> |
+-------------------------+------------------------------+
8.1.4.
Address Block TLV Block
Address Block TLVs are always associated with addresses in the
Address Block. The following sections show the TLVs that apply to
each address.
8.1.4.1.
Address Block TLVs for OrigAddr
+--------------+---------------+------------+-----------------------+
| Data Element | TLV Type
| Extension | Value
|
|
|
| Type
|
|
+--------------+---------------+------------+-----------------------+
| None
| ADDRESS_TYPE | 0
| ADDRTYPE_ORIGADDR
|
| OrigSeqNum
| SEQ_NUM
| 0
| Sequence Number of
|
|
|
|
| RREQ_Gen, the router |
|
|
|
| which initiated route |
|
|
|
| discovery.
|
| OrigMetric
| PATH_METRIC
| MetricType | Metric for the route |
| /MetricType |
|
| to OrigAddr, using
|
|
|
|
| MetricType.
|
| ValidityTime | VALIDITY_TIME | 0
| ValidityTime for
|
|
|
|
| route to OrigAddr.
|
+--------------+---------------+------------+-----------------------+
In the AODVv2 representation, if the message relates to
DEFAULT_METRIC_TYPE, MetricType is not included in the message.
RFC 5444 representation will set the extension type in the
PATH_METRIC TLV to 0. AODVv2 interprets a MetricType of 0 as
DEFAULT_METRIC_TYPE.
8.1.4.2.
The
Address Block TLVs for TargAddr
+------------+--------------+-------------+-------------------------+
| Data
| TLV Type
| Extension
| Value
|
| Element
|
| Type
|
|
+------------+--------------+-------------+-------------------------+
| None
| ADDRESS_TYPE | 0
| ADDRTYPE_TARGADDR
|
| TargSeqNum | SEQ_NUM
| 0
| The last known
|
|
|
|
| TargSeqNum for
|
|
|
|
| TargAddr.
|
+------------+--------------+-------------+-------------------------+
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8.2.
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8.2.1.
RREP
Message Header
+---------------+-----------------+---------------------------------+
| Data Element | Header Field
| Value
|
+---------------+-----------------+---------------------------------+
| None
| <msg-type>
| RREP
|
| msg_hop_limit | <msg-hop-limit> | <msg-hop-count> from
|
|
|
| corresponding RREQ.
|
| msg_hop_count | <msg-hop-count> | Number of hops traversed so far |
|
|
| by the message.
|
+---------------+-----------------+---------------------------------+
8.2.2.
Message TLV Block
A RREP contains no Message TLVs.
8.2.3.
Address Block
A RREP contains a minimum of two Addresses, OrigAddr and TargAddr,
and each address has an associated prefix length. If the prefix
length has not been included in the AODVv2 message, it is equal to
the address length in bits.
It may also contain the address of the intended next hop, in order to
request acknowledgement to confirm adjacency, as described in
Section 6.2. The prefix length associated with this address is equal
to the address length in bits.
+-------------------------+------------------------------+
| Data Elements
| Address Block
|
+-------------------------+------------------------------+
| OrigAddr/OrigPrefixLen | <address> + <prefix-length> |
| TargAddr/TargPrefixLen | <address> + <prefix-length> |
| AckReq
| <address> + <prefix-length> |
+-------------------------+------------------------------+
8.2.4.
Address Block TLV Block
Address Block TLVs are always associated with addresses in the
Address Block. The following sections show the TLVs that apply to
each address.
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Address Block TLVs for OrigAddr
+-------------+---------------+----------------+--------------------+
| Data
| TLV Type
| Extension Type | Value
|
| Element
|
|
|
|
+-------------+---------------+----------------+--------------------+
| None
| ADDRESS_TYPE | 0
| ADDRTYPE_ORIGADDR |
+-------------+---------------+----------------+--------------------+
8.2.4.2.
Address Block TLVs for TargAddr
+--------------+---------------+------------+-----------------------+
| Data Element | TLV Type
| Extension | Value
|
|
|
| Type
|
|
+--------------+---------------+------------+-----------------------+
| None
| ADDRESS_TYPE | 0
| ADDRTYPE_TARGADDR
|
| TargSeqNum
| SEQ_NUM
| 0
| Sequence number of
|
|
|
|
| RREP_Gen, the router |
|
|
|
| which created the
|
|
|
|
| RREP.
|
| TargMetric
| PATH_METRIC
| MetricType | Metric for the route |
| /MetricType |
|
| to TargAddr, using
|
|
|
|
| MetricType.
|
| ValidityTime | VALIDITY_TIME | 0
| ValidityTime for
|
|
|
|
| route to TargAddr.
|
+--------------+---------------+------------+-----------------------+
In the AODVv2 representation, if the message relates to
DEFAULT_METRIC_TYPE, MetricType is not included in the message.
RFC 5444 representation will set the extension type in the
PATH_METRIC TLV to 0. AODVv2 interprets a MetricType of 0 as
DEFAULT_METRIC_TYPE.
8.2.4.3.
The
Address Block TLVs for AckReq Intended Recipient Address
+--------------+---------------+-----------------+------------------+
| Data Element | TLV Type
| Extension Type | Value
|
+--------------+---------------+-----------------+------------------+
| None
| ADDRESS_TYPE | 0
| ADDRTYPE_INTEND |
+--------------+---------------+-----------------+------------------+
8.3.
8.3.1.
RREP_Ack
Message Header
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+---------------+---------------+-----------+
| Data Element | Header Field | Value
|
+---------------+---------------+-----------+
| None
| <msg-type>
| RREP_Ack |
+---------------+---------------+-----------+
8.3.2.
Message TLV Block
A RREP_Ack contains no Message TLVs.
8.3.3.
Address Block
A RREP_Ack contains no Address Block.
8.3.4.
Address Block TLV Block
A RREP_Ack contains no Address Block TLV Block.
8.4.
8.4.1.
RERR
Message Header
+----------------+------------------+---------------+
| Data Element
| Header Field
| Value
|
+----------------+------------------+---------------+
| None
| <msg-type>
| RERR
|
| msg_hop_limit | <msg-hop-limit> | MAX_HOPCOUNT |
+----------------+------------------+---------------+
8.4.2.
Message TLV Block
A RERR contains no Message TLVs.
8.4.3.
Address Block
The Address Block in a RERR may contain PktSource, the source IP
address of the packet triggering RERR generation, as detailed in
Section 7.4. Prefix Length associated with PktSource is equal to the
address length in bits.
Address Block always contains one Address per route that is no longer
valid, and each address has an associated prefix length. If a prefix
length has not been included for this address, it is equal to the
address length in bits.
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+------------------------------+------------------------------------+
| Data Element
| Address Block
|
+------------------------------+------------------------------------+
| PktSource
| <address> + <prefix-length> for
|
|
| PktSource
|
| AddressList/PrefixLengthList | <address> + <prefix-length> for
|
|
| each unreachable address in
|
|
| AddressList
|
+------------------------------+------------------------------------+
8.4.4.
Address Block TLV Block
Address Block TLVs are always associated with addresses in the
Address Block. The following sections show the TLVs that apply to
each type of address in the RERR.
8.4.4.1.
Address Block TLVs for PktSource
+--------------+---------------+---------------+--------------------+
| Data Element | TLV Type
| Extension
| Value
|
|
|
| Type
|
|
+--------------+---------------+---------------+--------------------+
| PktSource
| ADDRESS_TYPE | 0
| ADDRTYPE_PKTSOURCE |
+--------------+---------------+---------------+--------------------+
8.4.4.2.
Address Block TLVs for Unreachable Addresses
+----------------+--------------+------------+----------------------+
| Data Element
| TLV Type
| Extension | Value
|
|
|
| Type
|
|
+----------------+--------------+------------+----------------------+
| None
| ADDRESS_TYPE | 0
| ADDRTYPE_UNREACHABLE |
| SeqNumList
| SEQ_NUM
| 0
| Sequence Number
|
|
|
|
| associated with
|
|
|
|
| invalid route to the |
|
|
|
| unreachable address. |
| MetricTypeList | PATH_METRIC | MetricType | None. Extension Type |
|
|
|
| set to MetricType of |
|
|
|
| the route to the
|
|
|
|
| unreachable address. |
+----------------+--------------+------------+----------------------+
Using the PATH_METRIC TLV without a value is a mechanism used in RERR
messages to indicate the MetricType associated with the route being
reported, without the need to include a Metric value. Multiple
PATH_METRIC TLVs may be necessary if routes with multiple MetricTypes
are included in the RERR.
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In the AODVv2 representation, if the RERR message includes only
routes with DEFAULT_METRIC_TYPE, MetricType is not included in the
message. In this case, the RFC 5444 representation does not need to
include a PATH_METRIC TLV to indicate the DEFAULT_METRIC_TYPE. If
the RERR message includes both routes with DEFAULT_METRIC_TYPE and
other MetricTypes, only the routes with non-default MetricType need
to be marked with a PATH_METRIC TLV using Extension Type to indicate
MetricType. AODVv2 interprets the absence of MetricType information
as an indication of DEFAULT_METRIC_TYPE.
9.
Simple Internet Attachment
Figure 4 shows a stub (i.e., non-transit) network of AODVv2 routers
which is attached to the Internet via a single Internet AODVv2 Router
(abbreviated IAR). The interface to the Internet MUST NOT be
configured in the AODVv2_INTERFACES list.
As in any Internet-attached network, AODVv2 routers and clients that
wish to be reachable from hosts on the Internet MUST have IP
addresses within the IAR’s routable and topologically correct prefix
(i.e., 191.0.2.0/24). This AODVv2 network and subnets within it will
be advertised to the internet using procedures which are out of scope
for this specification.
/-------------------------\
/ +----------------+
\
/ | AODVv2 Router |
\
| | 191.0.2.2/32 |
|
| +----------------+
|
Routable
|
+-----+--------+
Prefix
|
|
Internet
| /191.0.2.0/24
|
| AODVv2 Router| /
|
| 191.0.2.1
|/
/---------------\
|
| serving net +------+
Internet
\
|
| 191.0.2.0/24 |
\
/
|
+-----+--------+
\---------------/
|
+----------------+ |
|
| AODVv2 Router | |
|
| 191.0.2.3/32 | |
\
+----------------+ /
\
/
\-------------------------/
Figure 4: Simple Internet Attachment Example
When an AODVv2 router within the AODVv2 MANET wants to discover a
route toward a node on the Internet, it uses the normal AODVv2 route
discovery for that IP Destination Address. The IAR MUST respond to
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RREQ on behalf of all Internet destinations, i.e., destinations not
on the configured 191.0.2.0/24 subnet.
When a packet from a node on the Internet destined for a node in the
AODVv2 MANET reaches the IAR, if the IAR does not have a route toward
that exact destination it will perform normal AODVv2 route discovery
for that destination.
Configuring the IAR as a default router is outside the scope of this
specification.
10.
Optional Features
A number of optional features for AODVv2, associated initially with
AODV, MAY be useful in networks with greater mobility or larger node
populations, or networks requiring reduced latency for application
launches. These features are not required by minimal
implementations.
10.1.
Expanding Rings Multicast
For multicast RREQ, msg_hop_limit MAY be set in accordance with an
expanding ring search as described in [RFC3561] to limit the RREQ
propagation to a subset of the local network and possibly reduce
route discovery overhead.
10.2.
Precursor Lists
This section specifies an interoperable enhancement to AODVv2
enabling more economical RERR notifications.
There can be several sources of traffic for a certain destination.
Each source of traffic and each upstream router between the
forwarding AODVv2 router and the traffic source is known as a
"precursor" for the destination. For each destination, an AODVv2
router MAY choose to keep track of precursors that have provided
traffic for that destination. Route Error messages about that
destination can be sent unicast to these precursors instead of
multicast to all AODVv2 routers.
Since a RERR will be regenerated if it comes from a next hop on a
valid route, the RERR should ideally be sent backwards along the
route that the source of the traffic uses, to ensure it is
regenerated at each hop and reaches the traffic source. If the
reverse path is unknown, the RERR should be sent toward the source
along some other route. Therefore, the options for saving precursor
information are as follows:
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o
Save the next hop on an existing route to the packet’s source
address as the precursor. In this case, it is not guaranteed that
a RERR that is sent will follow the reverse of the source’s route.
In rare situations, this may prevent the route from being
invalidated at the source of the data traffic.
o
Save the packet’s source address as the precursor. In this case,
the RERR can be sent along any existing route to the source of the
data traffic, and should include the PktSource data element to
ensure that the route will be invalidated at the source of the
traffic, in case the RERR does not follow the reverse of the
source’s route.
o
By inspecting the MAC address of each forwarded packet, determine
which router forwarded the packet, and save the router address as
a precursor. This ensures that when a RERR is sent to the
precursor router, the route will be invalidated at that router,
and the RERR will be regenerated toward the source of the packet.
During normal operation, each AODVv2 router maintaining precursor
lists for a route must update the precursor list whenever it uses
this route to forward traffic to the destination. Precursors are
classified as Active if traffic has recently been forwarded by the
precursor. The precursor is marked with a timestamp to indicate the
time it last forwarded traffic on this route.
When an AODVv2 router detects that one or more routes are broken, it
MAY notify each Active precursor using a unicast Route Error message
instead of creating multicast traffic. Unicast is applicable when
there are few Active precursors compared to the number of neighboring
AODVv2 routers. However, the default multicast behavior is still
preferable when there are many precursors, since fewer message
transmissions are required.
When an AODVv2 router supporting precursor lists receives a RERR
message, it MAY identify the list of its own affected Active
precursors for the routes in the RERR, and choose to send a unicast
RERR to those, rather than send a multicast RERR.
When a route is expunged, any precursor list associated with it must
also be expunged.
10.3.
Intermediate RREP
Without iRREP, only the AODVv2 router responsible for the target
address can respond to a RREQ. Using iRREP, route discoveries can be
faster and create less control traffic. This specification has been
published as a separate Internet Draft [I-D.perkins-irrep].
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10.4.
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Message Aggregation Delay
The aggregation of multiple messages into a packet is specified in
RFC 5444 [RFC5444].
Implementations MAY choose to briefly delay transmission of messages
for the purpose of aggregation (into a single packet) or to improve
performance by using jitter [RFC5148].
11.
Configuration
AODVv2 uses various parameters which can be grouped into the
following categories:
o
Timers
o
Protocol constants
o
Administrative parameters and controls
This section show the parameters along with their definitions and
default values (if any).
Note that several fields have limited size (bits or bytes). These
sizes and their encoding may place specific limitations on the values
that can be set.
11.1.
Timers
AODVv2 requires certain timing information to be associated with
route table entries and message replies. The default values are as
follows:
+------------------------+----------------+
| Name
| Default Value |
+------------------------+----------------+
| ACTIVE_INTERVAL
| 5 second
|
| MAX_IDLETIME
| 200 seconds
|
| MAX_BLACKLIST_TIME
| 200 seconds
|
| MAX_SEQNUM_LIFETIME
| 300 seconds
|
| RteMsg_ENTRY_TIME
| 12 seconds
|
| RREQ_WAIT_TIME
| 2 seconds
|
| RREP_Ack_SENT_TIMEOUT | 1 second
|
| RREQ_HOLDDOWN_TIME
| 10 seconds
|
+------------------------+----------------+
Table 3: Timing Parameter Values
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The above timing parameter values have worked well for small and
medium well-connected networks with moderate topology changes. The
timing parameters SHOULD be administratively configurable. Ideally,
for networks with frequent topology changes the AODVv2 parameters
should be adjusted using experimentally determined values or dynamic
adaptation. For example, in networks with infrequent topology
changes MAX_IDLETIME may be set to a much larger value.
11.2.
Protocol Constants
AODVv2 protocol constants typically do not require changes. The
following table lists these constants, along with their values and a
reference to the section describing their use.
+------------------------+---------+--------------------------------+
| Name
| Default | Description
|
+------------------------+---------+--------------------------------+
| DISCOVERY_ATTEMPTS_MAX | 3
| Section 6.4
|
| RREP_RETRIES
| 2
| Section 7.2.1
|
| MAX_METRIC[MetricType] | [TBD]
| Section 5
|
| MAX_METRIC[HopCount]
| 20 hops | Section 5 and Section 7
|
| MAX_HOPCOUNT
| 20
| Same as MAX_METRIC[HopCount]
|
| MAX_TIME
| [TBD]
| Maximum expressible clock time |
|
|
| (Section 6.5.2)
|
+------------------------+---------+--------------------------------+
Table 4: AODVv2 Constants
Note that <msg-hop-count> is an 8-bit field in the RFC 5444 message
header and therefore MAX_HOPCOUNT cannot be larger than 255. Field
lengths associated with metrics are to be found in Section 12.3.
MAX_METRIC[MetricType] MUST always be the maximum expressible metric
of type MetricType.
These protocol constants MUST have the same values for all AODVv2
routers in the ad hoc network. If the values were configured
differently, the following consequences may be observed:
o
DISCOVERY_ATTEMPTS_MAX: Nodes with higher values are likely to be
more successful at finding routes, at the cost of additional
control traffic.
o
RREP_RETRIES: Nodes with lower values are more likely to blacklist
neighbors when there is a temporary fluctuation in link quality.
o
MAX_HOPCOUNT: Nodes with a value too small would not be able to
discover routes to distant addresses.
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o
MAX_METRIC[MetricType]: No interoperability problems due to
variations on different nodes, but nodes with lower values may
exhibit overly restrictive behavior during route comparisons.
o
MAX_TIME: No interoperability problems due to variations on
different nodes, but if a lower value is used, route state
management may exhibit overly restrictive behavior.
11.3.
Local Settings
The following table lists AODVv2 parameters which should be
administratively configured for each node:
+------------------------+------------------------+--------------+
| Name
| Default Value
| Description |
+------------------------+------------------------+--------------+
| AODVv2_INTERFACES
|
| Section 3
|
| BUFFER_SIZE_PACKETS
| 2
| Section 6.4 |
| BUFFER_SIZE_BYTES
| MAX_PACKET_SIZE [TBD] | Section 6.4 |
| CLIENT_ADDRESSES
| AODVv2_INTERFACES
| Section 4.2 |
| CONTROL_TRAFFIC_LIMIT | [TBD - 50 pkts/sec?]
| Section 7
|
+------------------------+------------------------+--------------+
Table 5: Configuration for Local Settings
11.4.
Network-Wide Settings
The following administrative controls may be used to change the
operation of the network. The same settings should be used across
the network. Inconsistent settings at different nodes in the network
will not result in protocol errors, but poor performance may result,
especially if metrics are misinterpreted because DEFAULT_METRIC_TYPE
is configured differently at different nodes.
+----------------------+----------------------+----------------+
| Name
| Default
| Description
|
+----------------------+----------------------+----------------+
| DEFAULT_METRIC_TYPE | 3 (i.e., Hop Count) | [RFC6551]
|
| ENABLE_IDLE_IN_RERR | Disabled
| Section 7.4.1 |
+----------------------+----------------------+----------------+
Table 6: Configuration for Network-Wide Settings
11.5.
Optional Feature Settings
These options are not required for correct routing behavior, although
they may reduce AODVv2 protocol overhead in certain situations. The
default behavior is to leave these options disabled.
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+---------------------------+-----------+---------------------------+
| Name
| Default
| Description
|
+---------------------------+-----------+---------------------------+
| PRECURSOR_LISTS
| Disabled | Local (Section 10.2)
|
| MSG_AGGREGATION
| Disabled | Local (Section 10.4)
|
| ENABLE_IRREP
| Disabled | Network-wide (Section
|
|
|
| 10.3)
|
| EXPANDING_RINGS_MULTICAST | Disabled | Network-wide (Section
|
|
|
| 10.1)
|
+---------------------------+-----------+---------------------------+
Table 7: Configuration for Optional Features
12.
IANA Considerations
This section specifies several RFC 5444 message types, message tlvtypes, and address tlv-types required for AODVv2. Also, a new
registry of 16-bit metric types is specified.
12.1.
RFC 5444 Message Types
+-----------------------------------------+-----------+
| Name of Message
| Type
|
+-----------------------------------------+-----------+
| Route Request (RREQ)
| 10 (TBD) |
| Route Reply (RREP)
| 11 (TBD) |
| Route Error (RERR)
| 12 (TBD) |
| Route Reply Acknowledgement (RREP_Ack) | 13 (TBD) |
+-----------------------------------------+-----------+
Table 8: AODVv2 Message Types
12.2.
RFC 5444 Address Block TLV Types
+------------------------+----------+---------------+---------------+
| Name of TLV
| Type
| Length
| Reference
|
|
|
| (octets)
|
|
+------------------------+----------+---------------+---------------+
| PATH_METRIC
| 10 (TBD) | depends on
| Section 7
|
|
|
| MetricType
|
|
| SEQ_NUM
| 11 (TBD) | 2
| Section 7
|
| ADDRESS_TYPE
| 15 (TBD) | 1
| Section 8
|
| VALIDITY_TIME
| 1
| 1
| [RFC5497]
|
+------------------------+----------+---------------+---------------+
Table 9: AODVv2 Address Block TLV Types
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12.3.
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MetricType Allocation
Metric types are identified according to the assignments in
[RFC6551].
+------------------------+----------+--------------+
| Name of MetricType
| Type
| Metric Size |
+------------------------+----------+--------------+
| Unassigned
| 0
| Undefined
|
| Currently Unsupported | 1 - 2
| TBD
|
| Hop Count
| 3 [TBD] | 1 octet
|
| Currently Unsupported | 4 - 8
| TBD
|
| Unallocated
| 9 - 254 | TBD
|
| Reserved
| 255
| Undefined
|
+------------------------+----------+--------------+
Table 10: AODVv2 Metric Types
When creating AODVv2 messages which relate to the
DEFAULT_METRIC_TYPE, MetricType is not reported in the message. In
the RFC 5444 message representation, the PATH_METRIC TLV, if
included, will not include an extension type. While RFC 5444 would
interpret the lack of an extension type value as indication that
extension type is zero, AODVv2 will interpret an extension type of
zero to mean the DEFAULT_METRIC_TYPE configured on the router. This
is possible because zero is not assigned to any metric type
([RFC6551]). In RERR, the absence of the PATH_METRIC TLV also
indicates use of the DEFAULT_METRIC_TYPE.
12.4.
AddressType Allocation
The values used in the Address Type TLV used in Section 8 are given
in the table below:
+-----------------------+--------+
| Address Type
| Value |
+-----------------------+--------+
| ADDRTYPE_ORIGADDR
| 0
|
| ADDRTYPE_TARGADDR
| 1
|
| ADDRTYPE_UNREACHABLE | 2
|
| ADDRTYPE_PKTSOURCE
| 3
|
| ADDRTYPE_INTEND
| 4
|
+-----------------------+--------+
Table 11: AODVv2 Address Types
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13.
AODVv2
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Security Considerations
This section describes various security considerations and potential
avenues to secure AODVv2 routing. The objective of the AODVv2
protocol is for each router to communicate reachability information
about addresses for which it is responsible, and for routes it has
learned from other AODVv2 routers. Positive routing information
(i.e. a route exists) is distributed via RREQ and RREP messages.
Negative routing information (i.e. a route does not exist) is
distributed via RERR messages. AODVv2 routers store the information
contained in these messages in order to properly forward data
packets, and they generally provide this information to other AODVv2
routers.
Networks using AODVv2 to maintain connectivity and establish routes
on demand may be vulnerable to certain well-known types of threats.
Flooding attacks using RREQ amount to a denial of service for route
discovery. Valid route table entries can be replaced by maliciously
constructed RREQ and RREP messages. Links could be erroneously
treated as bidirectional if malicious unsolicited RREP or RREP_Ack
messages were to be accepted. Replay attacks using RERR messages
could, in some circumstances, be used to disrupt active routes.
Passive inspection of AODVv2 control messages could enable
unauthorized devices to gain information about the network topology,
since exchanging such information is the main purpose of AODVv2.
The on-demand nature of AODVv2 route discovery reduces the
vulnerability to route disruption. Since control traffic for
updating route tables is diminished, there is less opportunity for
failure. Processing requirements for AODVv2 are typically quite
small, and would typically be dominated by calculations to verify
integrity. This has the effect of reducing (but by no means
eliminating) AODVv2’s vulnerability to denial of service attacks.
Encryption MAY be used for AODVv2 messages. If the routers share a
packet-level security association, the message data can be encrypted
prior to message transmission. The establishment of such security
associations is outside the scope of this specification. Encryption
will not only protect against unauthorized devices obtaining
information about network topology but will ensure that only trusted
routers participate in routing operations.
Message integrity checking is enabled by the Integrity Check Value
mechanisms defined in [RFC7182]. The data contained in AODVv2
routing protocol messages SHOULD be verified using ICV values, to
avoid the use of message data if the message has been tampered with
or replayed. Otherwise, it would be possible to disrupt
communications by injecting nonexistent or malicious routes into the
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route tables of nodes within the ad hoc network. This can result in
loss of data or message processing by unauthorized devices.
The remainder of this section provides specific recommendations for
the use of the integrity checking and timestamp functions defined in
[RFC7182] to ensure the integrity of each AODVv2 message. The
calculation used for the Integrity Check Value will depend on the
message type. Sequence numbers can be used as timestamps to protect
against replay, since they are known to be strictly increasing.
RREQ messages advertise a route to OrigAddr, and impose very little
processing requirement for receivers. The main threat presented by
sending a RREQ message with false information is that traffic to
OrigAddr could be disrupted. Since RREQ is multicast and likely to
be received by all nodes in the ad hoc network, this threat could
have serious impact on applications communicating by way of OrigAddr.
The actual threat to disrupt routes to OrigAddr is reduced by the
AODVv2 mechanism of marking RREQ-derived routes as "Unconfirmed"
until adjacency with the next hop is confirmed. If AODVv2 routers
always verify the integrity of the RREQ message data, then the threat
of disruption is minimized. The ICV mechanisms offered in [RFC7182]
are sufficient for this purpose. Since OrigAddr is included as a
data element of the RREQ, the ICV can be calculated and verified
using message contents. The ICV should be verified at every step
along the dispersal path of the RREQ to mitigate the threat. Since
RREQ_Gen’s sequence number is incremented for each new RREQ, replay
protection is already afforded and no extra timestamp mechanism is
required.
RREP messages advertise a route to TargAddr, and impose very little
processing requirement for receivers. The main threat presented by
sending a RREP message with false information is that traffic to
TargAddr could be disrupted. Since RREP is unicast, this threat is
restricted to receivers along the path from OrigAddr to TargAddr. If
AODVv2 routers always verify the integrity of the RREP message data,
then this threat is minimized. This facility is offered by the ICV
mechanisms in [RFC7182]. Since TargAddr is included as a data
element of the RREP, the ICV can be calculated and verified using
message contents. The ICV should be verified at every step along the
unicast path of the RREP. Since RREP_Gen’s sequence number is
incremented for each new RREP, replay protection is afforded and no
extra timestamp mechanism is required.
RREP_Ack messages are intended to verify bidirectional neighbor
connectivity, and impose very little processing requirement for
receivers. The main threat presented by sending a RREP_Ack message
with false information is that the route advertised to a target node
in a RREP might be erroneously accepted even though the route would
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contain a unidirectional link and thus not be suitable for most
traffic. Since RREP_Ack is unicast, this threat is strictly local to
the RREP transmitter expecting the acknowledgement. A malicious
router could also attempt to send an unsolicited RREP_Ack to convince
another router that a bidirectional link exists and subsequently use
further messages to divert traffic along a route which is not valid.
If AODVv2 routers always verify the integrity of the RREP_Ack message
data, then this threat is minimized. This facility is offered by the
ICV mechanisms in [RFC7182]. The RREP_Gen SHOULD use the source IP
address of the RREP_Ack to identify the sender, and so the ICV should
be calculated using the message contents and the IP source address.
The message must also include the Timestamp defined in [RFC7182] to
protect against replay attacks, using TargSeqNum from the RREP as the
value in the TIMESTAMP TLV.
RERR messages remove routes, and impose very little processing
requirement for receivers. The main threat presented by sending a
RERR message with false information is that traffic to the advertised
destinations could be disrupted. Since RERR is multicast and can be
received by many routers in the ad hoc network, this threat could
have serious impact on applications communicating by way of the
sender of the RERR message. However, since the sender of the RERR
message with erroneous information may be presumed to be either
malicious or broken, it is better that such routes not be used
anyway. Another threat is that a malicious RERR message may be sent
with a PktSource data element included, to disrupt PktSource’s
ability to send to the addresses contained in the RERR. If AODVv2
routers always verify the integrity of the RERR message data, then
this threat is reduced. This facility is offered by the ICV
mechanisms in [RFC7182]. The receiver of the RERR SHOULD use the
source IP address of the RERR to identify the sender. The message
must also include the Timestamp defined in [RFC7182] to protect
against replay attacks, using SeqNum from RERR_Gen as the value in
the TIMESTAMP TLV.
14.
Acknowledgments
AODVv2 is a descendant of the design of previous MANET on-demand
protocols, especially AODV [RFC3561] and DSR [RFC4728]. Changes to
previous MANET on-demand protocols stem from research and
implementation experiences. Thanks to Elizabeth Belding and Ian
Chakeres for their long time authorship of AODV. Additional thanks
to Derek Atkins, Emmanuel Baccelli, Abdussalam Baryun, Ramon Caceres,
Thomas Clausen, Justin Dean, Christopher Dearlove, Ulrich Herberg,
Henner Jakob, Luke Klein-Berndt, Lars Kristensen, Tronje Krop,
Koojana Kuladinithi, Kedar Namjoshi, Keyur Patel, Alexandru Petrescu,
Henning Rogge, Fransisco Ros, Pedro Ruiz, Christoph Sommer, Romain
Thouvenin, Richard Trefler, Jiazi Yi, Seung Yi, and Cong Yuan, for
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their reviews AODVv2 and DYMO, as well as numerous specification
suggestions.
15.
References
15.1.
Normative References
[RFC2119]
Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC4291]
Hinden, R. and S. Deering, "IP Version 6 Addressing
Architecture", RFC 4291, February 2006.
[RFC5082]
Gill, V., Heasley, J., Meyer, D., Savola, P., and C.
Pignataro, "The Generalized TTL Security Mechanism
(GTSM)", RFC 5082, October 2007.
[RFC5444]
Clausen, T., Dearlove, C., Dean, J., and C. Adjih,
"Generalized Mobile Ad Hoc Network (MANET) Packet/Message
Format", RFC 5444, February 2009.
[RFC5497]
Clausen, T. and C. Dearlove, "Representing Multi-Value
Time in Mobile Ad Hoc Networks (MANETs)", RFC 5497, March
2009.
[RFC5498]
Chakeres, I., "IANA Allocations for Mobile Ad Hoc Network
(MANET) Protocols", RFC 5498, March 2009.
[RFC6551]
Vasseur, JP., Kim, M., Pister, K., Dejean, N., and D.
Barthel, "Routing Metrics Used for Path Calculation in
Low-Power and Lossy Networks", RFC 6551, March 2012.
15.2.
Informative References
[I-D.perkins-irrep]
Perkins, C., "Intermediate RREP for dynamic MANET Ondemand (AODVv2) Routing", draft-perkins-irrep-03 (work in
progress), May 2015.
[Perkins94]
Perkins, C. and P. Bhagwat, "Highly Dynamic DestinationSequenced Distance-Vector Routing (DSDV) for Mobile
Computers", Proceedings of the ACM SIGCOMM ’94 Conference
on Communications Architectures, Protocols and
Applications, London, UK, pp. 234-244, August 1994.
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[Perkins99]
Perkins, C. and E. Royer, "Ad hoc On-Demand Distance
Vector (AODV) Routing", Proceedings of the 2nd IEEE
Workshop on Mobile Computing Systems and Applications, New
Orleans, LA, pp. 90-100, February 1999.
[RFC2501]
Corson, M. and J. Macker, "Mobile Ad hoc Networking
(MANET): Routing Protocol Performance Issues and
Evaluation Considerations", RFC 2501, January 1999.
[RFC3561]
Perkins, C., Belding-Royer, E., and S. Das, "Ad hoc OnDemand Distance Vector (AODV) Routing", RFC 3561, July
2003.
[RFC4193]
Hinden, R. and B. Haberman, "Unique Local IPv6 Unicast
Addresses", RFC 4193, October 2005.
[RFC4728]
Johnson, D., Hu, Y., and D. Maltz, "The Dynamic Source
Routing Protocol (DSR) for Mobile Ad Hoc Networks for
IPv4", RFC 4728, February 2007.
[RFC4861]
Narten, T., Nordmark, E., Simpson, W., and H. Soliman,
"Neighbor Discovery for IP version 6 (IPv6)", RFC 4861,
September 2007.
[RFC5148]
Clausen, T., Dearlove, C., and B. Adamson, "Jitter
Considerations in Mobile Ad Hoc Networks (MANETs)", RFC
5148, February 2008.
[RFC6130]
Clausen, T., Dearlove, C., and J. Dean, "Mobile Ad Hoc
Network (MANET) Neighborhood Discovery Protocol (NHDP)",
RFC 6130, April 2011.
[RFC6621]
Macker, J., "Simplified Multicast Forwarding", RFC 6621,
May 2012.
[RFC7182]
Herberg, U., Clausen, T., and C. Dearlove, "Integrity
Check Value and Timestamp TLV Definitions for Mobile Ad
Hoc Networks (MANETs)", RFC 7182, April 2014.
Appendix A.
Features Required of IP
AODVv2 needs the following:
o
information that IP routes are requested
o
information that packets are flowing
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the ability to queue packets
A reactive protocol reacts when a route is needed. A route is
requested when an application tries to send a packet. The
fundamental concept of reactive routing is to avoid creating routes
that are not needed. The trigger for route discovery is an
application trying to send a packet. If a route is not available to
forward the packet, the packet is queued while the route is
requested.
Appendix B.
Multi-homing Considerations
Multi-homing is not supported by the AODVv2 specification. The
coordination between multiple AODVv2 routers to distribute routing
information correctly for a shared address is not defined.
Previous work indicates that it can be supported by expanding the
sequence number to include the AODVv2 router’s IP address as a
parsable field of the SeqNum. Without this, comparing sequence
numbers would not work to evaluate freshness. Even when the IP
address is included, there is no good way to compare sequence numbers
from different IP addresses, but a handling node can determine
whether the two given sequence numbers are comparable. If the route
table can store multiple routes for the same destination, then multihoming can work with sequence numbers augmented by IP addresses.
This non-normative information is provided simply to document the
results of previous efforts to enable multi-homing. The intention is
to simplify the task of future specification if multihoming becomes
necessary for reactive protocol operation.
Appendix C.
Router Client Relocation
Only one AODVv2 router within a MANET SHOULD be responsible for a
particular address at any time. If two AODVv2 routers dynamically
shift the advertisement of a network prefix, correct AODVv2 routing
behavior must be observed. The AODVv2 router adding the new network
prefix must wait for any existing routing information about this
network prefix to be purged from the network, i.e., it must wait at
least MAX_SEQNUM_LIFETIME after the previous AODVv2 router’s last
SeqNum update for this network prefix.
Appendix D.
Example Algorithms for AODVv2 Operations
The following subsections show example algorithms for protocol
operations required by AODVv2. AODVv2 requires general algorithms
for manipulating and comparing table entries, and algorithms specific
to each message type.
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Processing for messages follows the following general outline:
1.
Receive incoming message.
2.
Update route table as appropriate.
3.
Respond as needed, often regenerating the incoming message with
updated information.
Once the route table has been updated, the information contained
there is known to be the most recent available information for any
fields in the outgoing message. For this reason, the algorithms are
written as if outgoing message field values are assigned from the
route table information, even though it is often equally appropriate
to use fields from the incoming message.
The following table indicates the field names used in subsequent
sections to describe the AODVv2 algorithms.
+-------------------------+-----------------------------------------+
| Parameter
| Description
|
+-------------------------+-----------------------------------------+
| RteMsg
| A route message
|
|
| (inRREQ/outRREQ/inRREP/outRREP)
|
| RteMsg.HopLimit
| Hop limit for the message
|
| RteMsg.HopCount
| Hop count for the message
|
| RteMsg.AckReq
| True/False, optional in RREP
|
| RteMsg.MetricType
| The type of metric included, optional
|
| RteMsg.OrigAddr
| Address of source of queued data
|
| RteMsg.TargAddr
| Address route is requested for
|
| RteMsg.OrigPrefixLen
| Prefix length of OrigAddr, optional
|
| RteMsg.TargPrefixLen
| Prefix length of TargAddr, optional
|
| RteMsg.OrigSeqNum
| SeqNum of OrigAddr, in RREQ only
|
| RteMsg.TargSeqNum
| SeqNum of TargAddr, in RREP, optional
|
|
| in RREQ
|
| RteMsg.OrigMetric
| Metric to OrigAddr, in RREQ only
|
| RteMsg.TargMetric
| Metric to TargAddr, in RREP only
|
| RteMsg.ValidityTime
| Time limit for route advertised
|
| RteMsg.NbrIP
| Sender of the RteMsg
|
| RteMsg.Netif
| Interface on which the RteMsg arrived
|
| AdvRte
| Derived from a RteMsg (see Section 6.5) |
| AdvRte.Address
| Route destination address
|
| AdvRte.PrefixLength
| Route destination prefix length
|
| AdvRte.SeqNum
| SeqNum associated with route
|
| AdvRte.MetricType
| MetricType associated with route
|
| AdvRte.Metric
| Advertised metric of route
|
| AdvRte.Cost
| Cost from receiving router
|
| AdvRte.ValidityTime
| Time limit for route advertised
|
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| AdvRte.NextHopIP
| Sender of the RteMsg
|
| AdvRte.NextHopIntf
| Interface on which the RteMsg arrived
|
| AdvRte.HopCount
| Number of hops traversed
|
| AdvRte.HopLimit
| Allowed number of hops remaining
|
| Route
| A route table entry (see Section 4.6)
|
| Route.Address
| Route destination address
|
| Route.PrefixLength
| Route destination prefix length
|
| Route.SeqNum
| SeqNum associated with route
|
| Route.NextHop
| Address of router which advertised the |
|
| route
|
| Route.NextHopInterface | Interface on which next hop is
|
|
| reachable
|
| Route.LastUsed
| Time this route was last used for
|
|
| packet forwarding
|
| Route.LastSeqNumUpdate | Time the SeqNum of the route was last
|
|
| updated
|
| Route.ExpirationTime
| Time at which the route will expire
|
| Route.MetricType
| MetricType associated with route
|
| Route.Metric
| Cost from receiving router
|
| Route.State
| Active/Idle/Invalid
|
| Route.Precursors
| Optional (see Section 10.2)
|
| RERR
| Route Error message (inRERR/outRERR)
|
| RERR.HopLimit
| Hop limit for the message
|
| RERR.PktSource
| Source address of packet which
|
|
| triggered RERR
|
| RERR.AddressList[]
| List of unreachable route addresses
|
| RERR.PrefixLengthList[] | List of PrefixLengths for AddressList
|
| RERR.SeqNumList[]
| List of SeqNums for AddressList
|
| RERR.MetricTypeList[]
| MetricType for the invalid routes
|
| RERR.Netif
| Interface on which the RERR arrived
|
+-------------------------+-----------------------------------------+
Table 12: Notation used in Appendix
D.1.
D.1.1.
General Operations
Check_Route_State
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/*
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July 2015
Update the state of the route entry based on timeouts. Return
whether the route can be used for forwarding a packet. */
Check_Route_State(route)
{
if (CurrentTime > route.ExpirationTime)
route.State := Invalid;
if ((CurrentTime - route.LastUsed > ACTIVE_INTERVAL + MAX_IDLETIME)
AND (route.State != Unconfirmed)
AND (route.ExpirationTime == MAX_TIME)) //not a timed route
route.State := Invalid;
if ((CurrentTime - route.LastUsed > ACTIVE_INTERVAL)
AND (route.State != Unconfirmed)
AND (route.ExpirationTime == MAX_TIME)) //not a timed route
route.State := Idle;
if ((CurrentTime - route.LastSeqNumUpdate > MAX_SEQNUM_LIFETIME)
AND (route.State == Invalid OR route.State == Unconfirmed))
/* remove route from route table */
if ((CurrentTime - route.LastSeqNumUpdate > MAX_SEQNUM_LIFETIME)
AND (route.State != Invalid)
route.SeqNum := 0;
if (route still exists AND route.State != Invalid
AND Route.State != Unconfirmed)
return TRUE;
else
return FALSE;
}
D.1.2.
Process_Routing_Info
(See Section 6.5.1)
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/* Compare incoming route information to stored route, and if better,
use to update stored route. */
Process_Routing_Info (advRte)
{
rte := Fetch_Route_Table_Entry (advRte);
if (!rte exists)
{
rte := Create_Route_Table_Entry(advRte);
return rte;
}
if (AdvRte.SeqNum > Route.SeqNum
/* stored route is stale
OR
(AdvRte.SeqNum == Route.SeqNum
/* same SeqNum
AND
((Route.State == Invalid AND LoopFree(advRte, rte))
/* advRte can repair stored
OR AdvRte.Cost < Route.Metric)))
/* advRte is better
{
if (advRte is from a RREQ)
rte := Create_Route_Table_Entry(advRte);
else
Update_Route_Table_Entry (rte, advRte);
}
return rte;
*/
*/
*/
*/
}
D.1.3.
Fetch_Route_Table_Entry
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/* Lookup a route table entry matching an advertised route */
Fetch_Route_Table_Entry (advRte)
{
foreach (rteTableEntry in rteTable)
{
if (rteTableEntry.Address == advRte.Address
AND rteTableEntry.MetricType == advRte.MetricType)
return rteTableEntry;
}
return null;
}
/* Lookup a route table entry matching address and metric type */
Fetch_Route_Table_Entry (destination, metricType)
{
foreach (rteTableEntry in rteTable)
{
if (rteTableEntry.Address == destination
AND rteTableEntry.MetricType == metricType)
return rteTableEntry;
}
return null;
}
D.1.4.
Update_Route_Table_Entry
/* Update a route table entry using AdvRte in received RteMsg */
Update_Route_Table_Entry (rte, advRte);
{
rte.SeqNum := advRte.SeqNum;
rte.NextHop := advRte.NextHopIp;
rte.NextHopInterface := advRte.NextHopIntf;
rte.LastUsed := CurrentTime;
rte.LastSeqNumUpdate := CurrentTime;
if (validityTime)
rte.ExpirationTime := CurrentTime + advRte.ValidityTime;
else
rte.ExpirationTime := MAX_TIME;
rte.Metric := advRte.Cost;
if (rte.State == Invalid)
rte.State := Idle (if advRte is from RREP);
or Unconfirmed (if advRte is from RREQ);
}
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D.1.5.
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Create_Route_Table_Entry
/* Create a route table entry from address and prefix length */
Create_Route_Table_Entry (address, prefixLength, seqNum, metricType)
{
rte := allocate_memory();
rte.Address := address;
rte.PrefixLength := prefixLength;
rte.SeqNum := seqNum;
rte.MetricType := metricType;
}
/* Create a route table entry from the advertised route */
Create_Route_Table_Entry(advRte)
{
rte := allocate_memory();
rte.Address := advRte.Address;
if (advRte.PrefixLength)
rte.PrefixLength := advRte.PrefixLength;
else
rte.PrefixLength := maxPrefixLenForAddressFamily;
rte.SeqNum := advRte.SeqNum;
rte.NextHop := advRte.NextHopIp;
rte.NextHopInterface := advRte.NextHopIntf;
rte.LastUsed := CurrentTime;
rte.LastSeqNumUpdate := CurrentTime;
if (validityTime)
rte.ExpirationTime := CurrentTime + advRte.ValidityTime;
else
rte.ExpirationTime := MAX_TIME;
rte.MetricType := advRte.MetricType;
rte.Metric := advRte.Metric;
rte.State := Idle (if advRte is from RREP);
or Unconfirmed (if advRte is from RREQ);
}
D.1.6.
LoopFree
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/* Return TRUE if the route advRte is LoopFree compared to rte */
LoopFree(advRte, rte)
{
if (advRte.Cost <= rte.Cost)
return TRUE;
else
return FALSE;
}
D.1.7.
Fetch_Rte_Msg_Table_Entry
/* Find an entry in the RteMsg table matching the given
message’s msg-type, OrigAddr, TargAddr, MetricType
*/
Fetch_Rte_Msg_Table_Entry (rteMsg)
{
foreach (entry in RteMsgTable)
{
if (entry.msg-type == rteMsg.msg-type
AND entry.OrigAddr == rteMsg.OrigAddr
AND entry.TargAddr == rteMsg.TargAddr
AND entry.MetricType == rteMsg.MetricType)
return entry;
}
return NULL;
}
D.1.8.
Update_Rte_Msg_Table
(See Section 4.5)
/* Update the multicast route message suppression table based on the
received RteMsg, return true if it was created or the SeqNum was
updated (i.e. it needs to be regenerated) */
Update_Rte_Msg_Table(rteMsg)
{
/* search for a comparable entry */
entry := Fetch_Rte_Msg_Table_Entry(rteMsg);
/* if there is none, create one */
if (entry does not exist)
{
entry.MessageType := rteMsg.msg_type;
entry.OrigAddr := rteMsg.OrigAddr;
entry.TargAddr := rteMsg.TargAddr;
entry.OrigSeqNum := rteMsg.origSeqNum; // (if present)
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entry.TargSeqNum := rteMsg.targSeqNum; // (if present)
entry.MetricType := rteMsg.MetricType;
entry.Metric := rteMsg.OrigMetric; // (for RREQ)
or rteMsg.TargMetric; // (for RREP)
entry.Timestamp := CurrentTime;
return TRUE;
}
/* if current entry is stale */
if (
(rteMsg.msg-type == RREQ AND entry.OrigSeqNum
OR
(rteMsg.msg-type == RREP AND entry.TargSeqNum
{
entry.OrigSeqNum := rteMsg.OrigSeqNum; //
entry.TargSeqNum := rteMsg.TargSeqNum; //
entry.Timestamp := CurrentTime;
return TRUE;
}
< rteMsg.OrigSeqNum)
< rteMsg.TargSeqNum))
(if present)
(if present)
/* if received rteMsg is stale */
if (
(rteMsg.msg-type == RREQ AND entry.OrigSeqNum > rteMsg.OrigSeqNum)
OR
(rteMsg.msg-type == RREP AND entry.TargSeqNum > rteMsg.TargSeqNum))
{
entry.Timestamp := CurrentTime;
return FALSE;
}
/* if same SeqNum but rteMsg has lower metric */
if (entry.Metric > rteMsg.Metric)
entry.Metric := rteMsg.Metric;
entry.Timestamp := CurrentTime;
return FALSE;
}
D.1.9.
Build_RFC_5444_Message_Header
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/*
AODVv2
July 2015
This pseudocode shows possible RFC 5444 actions, and would not
be performed by the AODVv2 implementation. It is shown only to
provide more understanding about the AODVv2 message that will be
constructed by RFC 5444.
MAL := Message Address Length
MF := Message Flags
Size := number of octets in MsgHdr, AddrBlk, AddrTLVs */
Build_RFC_5444_Message_Header (msgType, Flags, AddrFamily, Size,
hopLimit, hopCount, tlvLength)
{
/* Build RFC 5444 message header fields */
msg-type := msgType;
MF := Flags;
MAL := 3 or 15; // for IPv4 or IPv6
msg-size := Size;
msg-hop-limit := hopLimit;
if (hopCount != 0) /* if hopCount is 0, do not include */
msg-hop-count := hopCount;
msg.tlvs-length := tlvLength;
}
D.2.
RREQ Operations
D.2.1.
/*
Generate_RREQ
Generate a route request message to find a route from OrigAddr
to TargAddr using the given MetricType
origAddr
:= IP address of Router Client which generated the
packet to be forwarded
origPrefix := prefix length associated with the Router Client
targAddr
:= destination IP address in the packet to be forwarded
targSeqNum := sequence number in existing route to targAddr
mType
:= metric type for the requested route
*/
Generate_RREQ(origAddr, origPrefix, targAddr, targSeqNum, mType)
{
/* Increment sequence number in nonvolatile storage */
mySeqNum := (1 + mySeqNum);
/* Marshall parameters */
outRREQ.HopLimit := MAX_HOPCOUNT;
outRREQ.HopCount := 0;
// if included
outRREQ.MetricType := mType;
//include if not DEFAULT_METRIC_TYPE
outRREQ.OrigAddr := origAddr;
outRREQ.TargAddr := targAddr;
outRREQ.OrigPrefixLen := origPrefix; //include if not address length
outRREQ.OrigSeqNum := mySeqNum;
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outRREQ.TargSeqNum := targSeqNum;
//included if available
outRREQ.OrigMetric := Route[OrigAddr].Metric;
//zero by default
outRREQ.ValidityTime := limit for route to OrigAddr;
//if required
/* Build Address Blk using prefix length information from
outRREQ.OrigPrefixLen if necessary */
AddrBlk := {outRREQ.OrigAddr, outRREQ.TargAddr};
/* Include sequence numbers in appropriate Address Block TLVs */
/* OrigSeqNum Address Block TLV */
origSeqNumAddrBlkTlv.value := outRREQ.OrigSeqNum;
/* TargSeqNum Address Block TLV */
if (outRREQ.TargSeqNum is known)
targSeqNumAddrBlkTlv.value := outRREQ.TargSeqNum;
/* Build Metric Address Block TLV, include Metric AddrBlkTlv
Extension type if a non-default metric */
metricAddrBlkTlv.value := outRREQ.OrigMetric;
if (outRREQ.MetricType != DEFAULT_METRIC_TYPE)
metricAddrBlkTlv.typeExtension := outRREQ.MetricType;
if (outRREQ.ValidityTime is required)
{
/* Build VALIDITY_TIME Address Block TLV */
VALIDITY_TIMEAddrBlkTlv.value := outRREQ.ValidityTime;
}
Build_RFC_5444_Message_Header (RREQ, 4, IPv4 or IPv6, NN,
outRREQ.HopLimit, outRREQ.HopCount, tlvLength);
/* multicast RFC 5444 message to LL-MANET-Routers */
}
D.2.2.
Receive_RREQ
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/*
AODVv2
July 2015
Process a RREQ received on link L */
Receive_RREQ (inRREQ, L)
{
if (inRREQ.NbrIP present in blacklist)
{
if (blacklist_expiration_time < CurrentTime)
return; // don’t process or regenerate RREQ
else
remove nbrIP from blacklist;
}
if (inRREQ does not contain msg_hop_limit, OrigAddr,
TargAddr, OrigSeqNum, OrigMetric)
return;
if (inRREQ.OrigAddr and inRREQ.TargAddr are not valid routable
and unicast addresses)
return;
if (inRREQ.MetricType is present but an unknown value)
return;
if (inRREQ.OrigMetric > MAX_METRIC[inRREQ.MetricType] - Cost(L))
return;
/* Extract inRREQ values */
advRte.Address := inRREQ.OrigAddr;
advRte.PrefixLength := inRREQ.OrigPrefixLen; (if present)
or the address length of advRte.Address;
advRte.SeqNum := inRREQ.OrigSeqNum;
advRte.MetricType := inRREQ.MetricType;
advRte.Metric := inRREQ.OrigMetric;
advRte.Cost := inRREQ.OrigMetric + Cost(L);
//according to the indicated MetricType
advRte.ValidityTime := inRREQ.ValidityTime; //if present
advRte.NextHopIP := inRREQ.NbrIP;
advRte.NextHopIntf := inRREQ.Netif;
advRte.HopCount := inRREQ.HopCount;
advRte.HopLimit := inRREQ.HopLimit;
rte := Process_Routing_Info (advRte);
/*
Update the RteMsgTable and determine if the RREQ needs
to be regenerated */
regenerate := Update_Rte_Msg_Table(inRREQ);
if (inRREQ.TargAddr is in Router Client list)
Generate_RREP(inRREQ, rte);
else if (regenerate)
Regenerate_RREQ(inRREQ, rte);
}
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D.2.3.
/*
AODVv2
July 2015
Regenerate_RREQ
Called from receive_RREQ()
rte := the route to OrigAddr */
Regenerate_RREQ (inRREQ, rte)
{
outRREQ.HopLimit := inRREQ.HopLimit - 1;
if (outRREQ.HopLimit == 0)
return; // don’t regenerate
if (inRREQ.HopCount exists)
{
if (inRREQ.HopCount >= MAX_HOPCOUNT)
return; // don’t regenerate
outRREQ.HopCount := inRREQ.HopCount + 1;
}
/* Marshall parameters */
outRREQ.MetricType := rte.MetricType;
outRREQ.OrigAddr := rte.Address;
outRREQ.TargAddr := inRREQ.TargAddr;
/* include prefix length if not equal to address length */
outRREQ.OrigPrefixLen := rte.PrefixLength;
outRREQ.OrigSeqNum := rte.SeqNum;
outRREQ.TargSeqNum := inRREQ.TargSeqNum; // if present
outRREQ.OrigMetric := rte.Metric;
outRREQ.ValidityTime := rte.ValidityTime;
or the time limit this router wishes to put on
route to OrigAddr
/*
Build Address Block using prefix length information from
outRREQ.OrigPrefixLen if necessary */
AddrBlk := {outRREQ.OrigAddr, outRREQ.TargAddr};
/* Include sequence numbers in appropriate Address Block TLVs */
/* OrigSeqNum Address Block TLV */
origSeqNumAddrBlkTlv.value := outRREQ.OrigSeqNum;
/* TargSeqNum Address Block TLV */
if (outRREQ.TargSeqNum is known)
targSeqNumAddrBlkTlv.value := outRREQ.TargSeqNum;
/* Build Metric Address Block TLV, include Metric AddrBlkTlv
Extension type if a non-default metric */
metricAddrBlkTlv.value := outRREQ.OrigMetric;
if (outRREQ.MetricType != DEFAULT_METRIC_TYPE)
metricAddrBlkTlv.typeExtension := outRREQ.MetricType;
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if (outRREQ.ValidityTime is required)
{
/* Build VALIDITY_TIME Address Block TLV */
VALIDITY_TIMEAddrBlkTlv.value := outRREQ.ValidityTime;
}
Build_RFC_5444_Message_Header (RREQ, 4, IPv4 or IPv6, NN,
outRREQ.HopLimit, outRREQ.HopCount, tlvLength);
/*
Multicast RFC 5444 message to LL-MANET-Routers, or if
inRREQ was unicast, the message can be unicast to the next
hop on the route to TargAddr, if known */
}
D.3.
RREP Operations
D.3.1.
Generate_RREP
Generate_RREP(inRREQ, rte)
{
/* Increment sequence number in nonvolatile storage */
mySeqNum := (1 + mySeqNum);
/* Marshall parameters */
outRREP.HopLimit := inRREQ.HopCount;
outRREP.HopCount := 0;
/* Include the AckReq when:
- previous RREP does not seem to enable any data flow, OR
- when RREQ is received from same OrigAddr after RREP was
unicast to rte.NextHop
*/
outRREP.AckReq := TRUE or FALSE; //TRUE if acknowledgement required
/* if included, set timeout RREP_Ack_SENT_TIMEOUT */
if (rte.MetricType != DEFAULT_METRIC_TYPE)
outRREP.MetricType := rte.MetricType;
outRREP.OrigAddr := rte.Address;
outRREP.TargAddr := inRREQ.TargAddr;
outRREP.TargPrefixLen := rte.PrefixLength; //if not address length
outRREP.TargSeqNum := mySeqNum;
outRREP.TargMetric := Route[TargAddr].Metric;
//zero by default
outRREP.ValidityTime := limit for route to TargAddr;
//if required
if (outRREP.AckReq == TRUE)
/* include AckReq Message TLV */
/*
Build Address Block using prefix length information from
outRREP.TargPrefixLen if necessary */
AddrBlk := {outRREP.OrigAddr, outRREP.TargAddr};
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/* TargSeqNum Address Block TLV */
targSeqNumAddrBlkTlv.value := outRREP.TargSeqNum;
/* Build Metric Address Block TLV include Metric AddrBlkTlv
Extension type if a non-default metric */
metricAddrBlkTlv.value := outRREP.TargMetric;
if (outRREP.MetricType != DEFAULT_METRIC_TYPE)
metricAddrBlkTlv.typeExtension := outRREP.MetricType;
if (outRREP.ValidityTime is required)
{
/* Build VALIDITY_TIME Address Block TLV */
VALIDITY_TIMEAddrBlkTlv.value := outRREP.ValidityTime;
}
Build_RFC_5444_Message_Header (RREP, 4, IPv4 or IPv6, NN,
outRREP.HopLimit, outRREQ.HopCount, tlvLength);
/* unicast RFC 5444 message to rte[OrigAddr].NextHop */
}
D.3.2.
/*
Receive_RREP
Process a RREP received on link L */
Receive_RREP (inRREP, L)
{
if (inRREP.NbrIP present in blacklist)
{
if (blacklist_expiration_time < CurrentTime)
return;
// don’t process or regenerate RREP
else
remove NbrIP from blacklist;
}
if (inRREP does not contain msg_hop_limit, OrigAddr,
TargAddr, TargSeqNum, TargMetric)
return;
if (inRREP.OrigAddr and inRREQ.TargAddr are not
valid routable and unicast addresses)
return;
if (inRREP.MetricType is present but an unknown value)
return;
if (inRREP.TargMetric > MAX_METRIC[inRREP.MetricType] - Cost(L))
return;
/* Extract inRREP values */
advRte.Address := inRREP.TargAddr;
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advRte.PrefixLength := inRREP.TargPrefixLen; //if present
or the address length of advRte.Address;
advRte.SeqNum := inRREP.TargSeqNum;
advRte.MetricType := inRREP.MetricType;
advRte.Metric := inRREP.TargMetric;
advRte.Cost := inRREP.TargMetric + Cost(L);
//according to the indicated MetricType
advRte.ValidityTime := inRREP.ValidityTime; //if present
advRte.NextHopIP := inRREP.NbrIP;
advRte.NextHopIntf := inRREP.Netif;
advRte.HopCount := inRREP.HopCount;
advRte.HopLimit := inRREP.HopLimit; //if included
rte := Process_Routing_Info (advRte);
‘
if (inRREP includes AckReq data element)
Generate_RREP_Ack(inRREP);
/*
Update the RteMsgTable and determine if the RREP needs
to be regenerated */
regenerate := Update_Rte_Msg_Table(inRREP);
if (inRREP.TargAddr is in the Router Client list)
send_buffered_packets(rte);
/* start to use the route */
else if (regenerate)
Regenerate_RREP(inRREP, rte);
}
D.3.3.
Regenerate_RREP
Regenerate_RREP(inRREP, rte)
{
if (rte does not exist)
{
Generate_RERR(inRREP);
return;
}
outRREP.HopLimit := inRREP.HopLimit - 1;
if (outRREP.HopLimit == 0) /* don’t regenerate */
return;
if (inRREP.HopCount exists)
{
if (inRREP.HopCount >= MAX_HOPCOUNT)
return; // don’t regenerate the RREP
outRREP.HopCount := inRREP.HopCount + 1;
}
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/* Marshall parameters */
/* Include the AckReq when:
- previous unicast RREP seems not to enable data flow, OR
- when RREQ is received from same OrigAddr after RREP
was unicast to rte.NextHop
*/
outRREP.AckReq := TRUE or FALSE; //TRUE if acknowledgement required
/* if included, set timeout RREP_Ack_SENT_TIMEOUT */
if (rte.MetricType != DEFAULT_METRIC_TYPE)
outRREP.MetricType := rte.MetricType;
outRREP.OrigAddr := inRREP.OrigAddr;
outRREP.TargAddr := rte.Address;
outRREP.TargPrefixLen := rte.PrefixLength; //if not address length
outRREP.TargSeqNum := rte.SeqNum;
outRREP.TargMetric := rte.Metric;
outRREP.ValidityTime := limit for route to TargAddr;
//if required
outRREP.NextHop := rte.NextHop
if (outRREP.AckReq == TRUE)
/* include AckReq Message TLV */
/*
Build Address Block using prefix length information from
outRREP.TargPrefixLen if necessary */
AddrBlk := {outRREP.OrigAddr, outRREP.TargAddr};
/* TargSeqNum Address Block TLV */
targSeqNumAddrBlkTlv.value := outRREP.TargSeqNum;
/* Build Metric Address Block TLV include Metric AddrBlkTlv
Extension type if a non-default metric */
metricAddrBlkTlv.value := outRREP.TargMetric;
if (outRREP.MetricType != DEFAULT_METRIC_TYPE)
metricAddrBlkTlv.typeExtension := outRREP.MetricType;
if (outRREP.ValidityTime is required)
{
/* Build VALIDITY_TIME Address Block TLV */
VALIDITY_TIMEAddrBlkTlv.value := outRREP.ValidityTime;
}
Build_RFC_5444_Message_Header (RREP, 4, IPv4 or IPv6, NN,
outRREP.HopLimit, 0, tlvLength);
/* unicast RFC 5444 message to rte[OrigAddr].NextHop */
}
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D.4.
AODVv2
July 2015
RREP_Ack Operations
D.4.1.
Generate_RREP_Ack
/* To be sent when a received RREP includes the AckReq data element */
Generate_RREP_Ack(inRREP)
{
Build_RFC_5444_Message_Header (RREP_Ack, 4, IPv4 or IPv6, NN,
1, 0, 0);
/* unicast RFC 5444 message to inRREP.NbrIP */
}
D.4.2.
Receive_RREP_Ack
Receive_RREP_Ack(inRREP_Ack)
{
/* cancel timeout event for the node sending RREP_Ack */
}
D.4.3.
Timeout_RREP_Ack
Timeout_RREP_Ack(outRREP)
{
if (numRetries < RREP_RETRIES)
/* resend RREP and double the previous timeout */
else
/* insert unresponsive node into blacklist */
}
D.5.
RERR Operations
D.5.1.
Generate_RERR
There are two parts to this function, based on whether it was
triggered by an undeliverable packet or a broken link to neighboring
AODVv2 router.
/*
Generate a Route Error message.
errorType := undeliverablePacket or brokenLink
*/
Generate_RERR(errorType, triggerPkt, brokenLinkNbrIp)
{
switch (errorType)
{
case (brokenLink):
doGenerate := FALSE;
num-broken-addr := 0;
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precursors[] := new empty precursor list;
outRERR.HopLimit := MAX_HOPCOUNT;
/* find routes which are now Invalid */
foreach (rte in route table)
{
if (brokenLinkNbrIp == rte.NextHop
AND (rte.State == Active
OR
(rte.State == Idle AND ENABLE_IDLE_IN_RERR)))
{
if (rte.State == Active)
doGenerate := TRUE;
rte.State := Invalid;
precursors += rte.Precursors (if any);
outRERR.AddressList[num-broken-addr] := rte.Address;
outRERR.PrefixLengthList[num-broken-addr] :=
rte.PrefixLength;
outRERR.SeqNumList[num-broken-addr] := rte.SeqNum;
outRERR.MetricTypeList[num-broken-addr] := rte.MetricType
num-broken-addr := num-broken-addr + 1;
}
}
}
case (undeliverablePacket):
doGenerate := TRUE;
num-broken-addr := 1;
outRERR.HopLimit := MAX_HOPCOUNT;
outRERR.PktSource := triggerPkt.SrcIP;
or triggerPkt.TargAddr; //if pkt was a RREP
outRERR.AddressList[0] := triggerPkt.DestIP;
or triggerPkt.OrigAddr; //if pkt was RREP
/* optional to include outRERR.PrefixLengthList, outRERR.SeqNumList
and outRERR.MetricTypeList */
}
if (doGenerate == FALSE)
return;
if (triggerPkt exists)
{
/* Build PktSource Message TLV */
pktSourceMessageTlv.value := outRERR.PktSource;
}
/*
The remaining steps add address, prefix length, sequence
number and metric type information for each unreachable address,
while conforming to the allowed MTU. If the MTU is reached, a new
message MUST be created. */
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/*
Build Address Block using prefix length information from
outRERR.PrefixLengthList[] if necessary */
AddrBlk := outRERR.AddressList[];
/* Optionally, add SeqNum Address Block TLV, including index values */
seqNumAddrBlkTLV := outRERR.SeqNumList[];
if (outRERR.MetricTypeList contains non-default MetricTypes)
/* include Metric Address Block TLVs with Type Extension set to
MetricType, including index values if necessary */
metricAddrBlkTlv.typeExtension := outRERR.MetricTypeList[];
Build_RFC_5444_Message_Header (RERR, 4, IPv4 or IPv6, NN,
outRERR.HopLimit, 0, tlvLength);
if (undeliverablePacket)
/* unicast outRERR to rte[outRERR.PktSource].NextHop */
else if (brokenLink)
/* unicast to precursors, or multicast to LL-MANET-Routers */
}
D.5.2.
Receive_RERR
Receive_RERR (inRERR)
{
if (inRERR does not contain msg_hop_limit and at least
one unreachable address)
return;
/*
Extract inRERR values, copy relevant unreachable addresses,
their prefix lengths, and sequence numbers to outRERR */
num-broken-addr := 0;
precursors[] := new empty precursor list;
foreach (unreachableAddress in inRERR.AddressList)
{
if (unreachableAddress is not valid routable and unicast)
continue;
if (unreachableAddress MetricType is present but an unknown value)
return;
/*
Find a matching route table entry, assume
DEFAULT_METRIC_TYPE if no MetricType included */
rte := Fetch_Route_Table_Entry (unreachableAddress,
unreachableAddress MetricType)
if (rte does not exist)
continue;
if (rte.State == Invalid)/* ignore already invalid routes */
continue;
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if ((rte.NextHop != inRERR.NbrIP
OR
rte.NextHopInterface != inRERR.Netif)
AND (PktSource is not present OR is not a Router Client))
continue;
if (unreachableAddress SeqNum (if known) < rte.SeqNum)
continue;
/* keep a note of all precursors of newly Invalid routes */
precursors += rte.Precursors; //if any
/* assume prefix length is address length if not included */
if (rte.PrefixLength != unreachableAddress prefixLength)
{
/* create new route with unreachableAddress information */
invalidRte := Create_Route_Table_Entry(unreachableAddress,
unreachableAddress PrefixLength,
unreachableAddress SeqNum,
unreachableAddress MetricType);
invalidRte.State := Invalid;
if (rte.PrefixLength > unreachableAddress prefixLength)
expunge_route(rte);
rte := invalidRte;
}
else if (rte.PrefixLength == unreachableAddress prefixLength)
rte.State := Invalid;
outRERR.AddressList[num-broken-addr] := rte.Address;
outRERR.PrefixLengthList[num-broken-addr] := rte.PrefixLength;
outRERR.SeqNumList[num-broken-addr] := rte.SeqNum;
outRERR.MetricTypeList[num-broken-addr] := rte.MetricType;
num-broken-addr := num-broken-addr + 1;
}
if (num-broken-addr AND (PktSource is not present OR PktSource is not
a Router Client))
Regenerate_RERR(outRERR, inRERR, precursors);
}
D.5.3.
Regenerate_RERR
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Regenerate_RERR (outRERR, inRERR, precursors)
{
/* Marshal parameters */
outRERR.HopLimit := inRERR.HopLimit - 1;
if (outRERR.HopLimit == 0) // don’t regenerate
return;
outRERR.PktSource := inRERR.PktSource; //if included
/* AddressList[], SeqNumList[], and PrefixLengthList[] are
already up-to-date */
if (outRERR.PktSource exists)
{
/* Build PktSource Message TLV */
pktSourceMessageTlv.value := outRERR.PktSource;
}
/*
Build Address Block using prefix length information from
outRERR.PrefixLengthList[] if necessary */
AddrBlk := outRERR.AddressList[];
/* Optionally, add SeqNum Address Block TLV, including index values */
seqNumAddrBlkTLV := outRERR.SeqNumList[];
if (outRERR.MetricTypeList contains non-default MetricTypes)
/* include Metric Address Block TLVs with Type Extension set to
MetricType, including index values if necessary */
metricAddrBlkTlv.typeExtension := outRERR.MetricTypeList[];
Build_RFC_5444_Message_Header (RERR, 4, IPv4 or IPv6, NN,
outRERR.HopLimit, 0, tlvLength);
if (outRERR.PktSource exists)
/* unicast RFC 5444 message to next hop towards
outRERR.PktSource */
else if (number of precursors == 1)
/* unicast RFC 5444 message to precursors[0] */
else if (number of precursors > 1)
/* unicast RFC 5444 message to all precursors, or multicast
RFC 5444 message to RERR_PRECURSORS if preferable */
else
/* multicast RFC 5444 message to LL-MANET-Routers */
}
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Appendix E.
E.1.
AODVv2
July 2015
AODVv2 Draft Updates
Changes between revisions 9 and 10
This section lists the changes between AODVv2 revisions ...-09.txt
and ...-10.txt.
o
Updated RFC 5444 Representation section to add "Address Type" TLV,
which explicitly declares the meaning of addresses in the RFC 5444
Address Block.
o
Relocated route state definitions.
throughout.
o
Updated definition of timed routes.
o
More consistent use of OrigPrefixLen, TargPrefixLen, and Invalid.
o
Mandated use of neighbor adjacency checking and support of AckReq
and RREP_Ack and clarified related text.
o
Changed order of LoopFree checking and route cost comparisons in
Evaluating Route Information.
o
Updated structure of section on Applying Route Updates.
o
Updated AckReq to include intended next hop address, and RREP to
be multicast if intended next hop is not a confirmed neighbor.
o
Clarified that gateway router is not default router.
E.2.
Minor improvements to clarity
Changes between revisions 8 and 9
This section lists the changes between AODVv2 revisions ...-08.txt
and ...-09.txt.
o
Numerous editorial improvements were made, including
relocation/removal/renaming/adding of some sections and text,
collection and tidying of scattered text on same topic, formatting
made more consistent to improve readability.
o
Removed mentions of precursors from main text, except one mention
in Route Table Entry.
o
Removed use of MIN_METRIC which was not defined.
o
Changed Current_Time to CurrentTime for consistency.
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July 2015
o
Changed OrigAddrMetric and TargAddrMetric to OrigMetric and
TargMetric respectively.
o
Updated Overview to simplify and provide a broader summary.
o
Updated Terminology definitions, Data Elements tables and combined
sections.
o
Updated Applicability Statement to move some of the nonapplicability text and to simplify what remains.
o
Updated TLV names to conform to existing naming style.
o
Updated Blacklist to be a NeighborList to include neighbors that
have confirmed bidirectional connectivity.
o
Updated messages processed if router on blacklist and which are
indicators of bidirectional links.
o
Added RemoveTime to RteMsg Table section.
o
Added short description of timed route to Route Table Entry
section but removed Route.Timed flag. Route is timed if its
expiration time is not MAX_TIME.
o
Added Unconfirmed route state for route to OrigAddr learned from
RREQ.
o
Updated AODVv2 Protocol Operations section and subsections,
including Initialization, Adjacency Monitoring, making algorithms
easier to read and making notation consistent, general
improvements to the text.
o
Updated Route Discovery, Retries and Buffering to include a more
complete description of the route discovery process.
o
Updated wording relating to different metric types.
o
Added text regarding control message limit in Message Transmission
section.
o
Added short explanation of positive/negative effects of buffering.
o
Simplified the packet diagrams, since some of their contents was
already explained in the text below and then again as part of
generation, reception and regeneration processes.
o
Clarified some elements of the message content descriptions.
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July 2015
o
Moved MetricType above MetricList in message sections, for
consistency.
o
Mirrored structure throughout AODVv2 Protocol Messages.
o
Changed RREQ and RREP’s use of Lists when only one entry is
necessary.
o
Added some pre-message-generation checks.
o
Ensured consistency in regeneration (if msg-hop-limit is reduced
to zero, do not regenerate).
o
Removed statements about neighbors but added blacklist checks
where necessary.
o
Noted that RREQ retries should increase the SeqNum.
o
Added statement that implementations SHOULD retry sending RREP.
o
Added text explaining what happens if RREP is lost, regarding
blacklisting and RREQ retries.
o
Removed hop limit from RREP_Ack.
check.
o
Updated RERR so that multiple metric types can be reported in the
same message.
o
Updated RERR reception processing to ensure PktSource deletes the
contained route.
o
Added text to show that if a router is the destination of a RERR,
the RERR is not regenerated.
o
Added text that RERRs should not be created if the same RERR has
recently been sent.
o
Updated RFC 5444 overview and simplified/rearranged text in this
section.
o
Major update to RFC 5444 representation section
o
Updated RERR’s RFC 5444 representation so that PktSource is placed
in Address Block, and updated IANA section to make PktSource an
Address Block TLV to indicate which address is PktSource.
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July 2015
o
Described use of extension type in Metric TLV to represent
MetricType, and the interpretation when using the default metric
type.
o
Removed Multicast RREP as an optional feature.
o
Updated Precursor Lists section to include options for precursor
information to store.
o
Updated Security Considerations.
E.3.
Changes between revisions 7 and 8
This section lists the changes between AODVv2 revisions ...-07.txt
and ...-08.txt.
o
MetricType is now an Address Block TLV. Minor changes to the
text. By using an extension type in the Metric TLV we can
represent MetricType more elegantly in the RFC 5444 message.
o
Updated Overview to be slightly more concise.
o
Moved MetricType next to Metric when mentioned for better flow.
o
Added text to Applicability to address comments on mailing list
regarding gateway behavior and NHDP HELLO messages.
o
Removed paragraph in AODVv2 Message Transmission section regarding
TTL.
o
Added reference where precursors are mentioned in route table
entry.
o
Added text to bidirectionality explanation regarding NHDP HELLO
messages and lower layer triggers.
o
Clarified blacklist removal with SHOULD rather than MAY.
o
Removed pseudo-code from section on evaluating incoming routing
information.
o
Clarified rules for expunging route entries on memory-constrained
devices.
o
Clarified the use of exponential backoff for route discovery
attempts.
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July 2015
o
Small updates to message sections.
if neighbors.
o
Renamed RFC 5444 parser to multiplexer in Section 10.
o
Removed "optional feature" to include multiple addresses in RERR.
o
Removed MetricType from the Message TLV Type Specification.
o
Updated Security Considerations.
o
Added reference to RFC 7182.
o
Small updates to message algorithms, including moving MetricType
from Message TLV to the Metric TLV in the Address Block TLV Block,
and only generating RERR if an Active route was made Invalid.
E.4.
Removed steps about checking
Changes between revisions 6 and 7
This section lists the changes since AODVv2 revision ...-06.txt
o
Added Victoria Mercieca as co-author.
o
Reorganized protocol message descriptions into major subsections
for each protocol message. For protocol messages, organized
processing into Generation, Reception, and Regeneration
subsections.
o
Separated RREQ and RREP message processing description into
separate major subsection which had previously been combined into
RteMsg description.
o
Enlarged RREQ Table function to include similar processing for
optional flooded RREP messages. The table name has been
correspondingly been changed to be the Table for Multicast
RteMsgs.
o
Moved sections for Multiple Interfaces and AODVv2 Control Message
Generation Limits to be major subsections of the AODVv2 Protocol
Operations section.
o
Reorganized the protocol message processing steps into the
subsections as previously described, adopting a more step-by-step
presentation.
o
Coalesced the router states Broken and Expired into a new combined
state named the Invalid state. No changes in processing are
required for this.
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July 2015
o
Merged the sections describing Next-hop Router Adjacency
Monitoring and Blacklists.
o
Specified that routes created during Route Discovery are marked as
Idle routes. If they are used for carrying data they become
Active routes.
o
Added Route.LastSeqNumUpdate information to route table, so that
route activity and sequence number validity can be tracked
separately. An active route can still forward traffic even if the
sequence number has not been refreshed within MAX_SEQNUM_LIFETIME.
o
Mandated implementation of RREP_Ack as response to AckReq Message
TLV in RREP messages.
Added field to RREP_Ack to ensure correspondence to the correct
AckReq message.
o
Added explanations for what happens if protocol constants are
given different values on different AODVv2 routers.
o
Specified that AODVv2 implementations are free to choose their own
heuristics for reducing multicast overhead, including RFC 6621.
o
Added appendix to identify AODVv2 requirements from OS
implementation of IP and ICMP.
o
Deleted appendix showing example RFC 5444 packet formats.
o
Clarification on the use of RFC 5497 VALIDITY_TIME.
o
In Terminology, deleted superfluous definitions, added missing
definitions.
o
Numerous editorial improvements and clarifications.
E.5.
Changes between revisions 5 and 6
This section lists the changes between AODVv2 revisions ...-05.txt
and ...-06.txt.
o
Added Lotte Steenbrink as co-author.
o
Reorganized section on Metrics to improve readability by putting
specific topics into subsections.
o
Introduced concept of data element, which is used to clarify the
method of enabling RFC 5444 representation for AODVv2 data
elements. A list of Data Elements was introduced in section 3,
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July 2015
which provides a better understanding of their role than was
previously supplied by the table of notational devices.
o
Replaced instances of OrigNode by OrigAddr whenever the more
specific meaning is appropriate. Similarly for instances of other
node versus address terminology.
o
Introduced concepts of PrefixLengthList and MetricList in order to
avoid use of index-based terminology such as OrigNdx and TargNdx.
o
Added section 5, "AODVv2 Message Transmission", describing the
intended interface to RFC 5444.
o
Included within the main body of the specification the mandatory
setting of the TLV flag thassingleindex for TLVs OrigSeqNum and
TargSeqNum.
o
Removed the Route.Timed state. Created a new flag for route table
entries known as Route.Timed. This flag can be set when the route
is in the active state. Previous description would require that
the route table entry be in two states at the same time, which
seems to be misleading. The new flag is used to clarify other
specification details for Timed routes.
o
Created table 3 to show the correspondence between AODVv2 data
elements and RFC 5444 message components.
o
Replaced "invalid" terminology by the more specific terms "broken"
or "expired" where appropriate.
o
Eliminated the instance of duplicate specification for inclusion
of OrigNode (now, OrigAddr) in the message.
o
Corrected the terminology to be Mid instead of Tail for the
trailing address bits of OrigAddr and TargAddr for the example
message formats in the appendices.
o
Repaired remaining instances of phraseology that could be
construed as indicating that AODV only supports a single network
interface.
o
Numerous editorial improvements and clarifications.
E.6.
Changes between revisions 4 and 5
This section lists the changes between AODVv2 revisions ...-04.txt
and ...-05.txt.
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July 2015
o
Normative text moved out of definitions into the relevant section
of the body of the specification.
o
Editorial improvements and improvements to consistent terminology
were made. Replaced "retransmit" by the slightly more accurate
term "regenerate".
o
Issues were resolved as discussed on the mailing list.
o
Changed definition of LoopFree as suggested by Kedar Namjoshi and
Richard Trefler to avoid the failure condition that they have
described. In order to make understanding easier, replaced
abstract parameters R1 by RteMsg and R2 by Route to reduce the
level of abstraction when the function LoopFree is discussed.
o
Added text to clarify that different metrics may have different
data types and different ranges of acceptable values.
o
Added text to section "RteMsg Structure" to emphasize the proper
use of RFC 5444.
o
Included within the main body of the specification the mandatory
setting of the TLV flag thassingleindex for TLVs OrigSeqNum and
TargSeqNum.
o
Made more extensive use of the AdvRte terminology, in order to
better distinguish between the incoming RREQ or RREP message
(i.e., RteMsg) versus the route advertised by the RteMsg (i.e.,
AdvRte).
E.7.
Changes between revisions 3 and 4
This section lists the changes between AODVv2 revisions ...-03.txt
and ...-04.txt.
o
An appendix was added to exhibit algorithmic code for
implementation of AODVv2 functions.
o
Numerous editorial improvements and improvements to consistent
terminology were made. Terminology related to prefix lengths was
made consistent. Some items listed in "Notational Conventions"
were no longer used, and so deleted.
o
Issues were resolved as discussed on the mailing list.
o
Appropriate instances of "may" were changed to "MAY".
o
Definition inserted for "upstream".
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July 2015
o
Route.Precursors included as an *optional* route table field
o
Reworded text to avoid use of "relevant".
o
Deleted references to "DestOnly" flag.
o
Refined statements about MetricType TLV to allow for omission when
MetricType == HopCount.
o
Bulletized list in section 8.1
o
ENABLE_IDLE_UNREACHABLE renamed to be ENABLE_IDLE_IN_RERR
o
Transmission and subscription to LL-MANET-Routers converted to
MUST from SHOULD.
E.8.
Changes between revisions 2 and 3
This section lists the changes between AODVv2 revisions ...-02.txt
and ...-03.txt.
o
The "Added Node" feature was removed. This feature was intended
to enable additional routing information to be carried within a
RREQ or a RREP message, thus increasing the amount of topological
information available to nodes along a routing path. However,
enlarging the packet size to include information which might never
be used can increase congestion of the wireless medium. The
feature can be included as an optional feature at a later date
when better algorithms are understood for determining when the
inclusion of additional routing information might be worthwhile.
o
Numerous editorial improvements and improvements to consistent
terminology were made. Instances of OrigNodeNdx and TargNodeNdx
were replaced by OrigNdx and TargNdx, to be consistent with the
terminology shown in Table 2.
o
Example RREQ and RREP message formats shown in the Appendices were
changed to use OrigSeqNum and TargSeqNum message TLVs instead of
using the SeqNum message TLV.
o
Inclusion of the OrigNode’s SeqNum in the RREP message is not
specified. The processing rules for the OrigNode’s SeqNum were
incompletely specified in previous versions of the draft, and very
little benefit is foreseen for including that information, since
reverse path forwarding is used for the RREP.
o
Additional acknowledgements were included, and contributors names
were alphabetized.
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July 2015
o
Definitions in the Terminology section capitalize the term to be
defined.
o
Uncited bibliographic entries deleted.
o
Ancient "Changes" sections were deleted.
Authors’ Addresses
Charles E. Perkins
Futurewei Inc.
2330 Central Expressway
Santa Clara, CA 95050
USA
Phone: +1-408-330-4586
Email: [email protected]
Stan Ratliff
Idirect
13861 Sunrise Valley Drive, Suite 300
Herndon, VA 20171
USA
Email: [email protected]
John Dowdell
Airbus Defence and Space
Celtic Springs
Newport, Wales NP10 8FZ
United Kingdom
Email: [email protected]
Lotte Steenbrink
HAW Hamburg, Dept. Informatik
Berliner Tor 7
D-20099 Hamburg
Germany
Email: [email protected]
Perkins, et al.
Expires January 7, 2016
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July 2015
Victoria Mercieca
Airbus Defence and Space
Celtic Springs
Newport, Wales NP10 8FZ
United Kingdom
Email: [email protected]
Perkins, et al.
Expires January 7, 2016
[Page 100]
Mobile Ad hoc Networks Working Group
Internet-Draft
Intended status: Standards Track
Expires: January 7, 2016
S. Ratliff
VT iDirect
B. Berry
S. Jury
Cisco Systems
D. Satterwhite
Broadcom
R. Taylor
Airbus Defence & Space
July 6, 2015
Dynamic Link Exchange Protocol (DLEP)
draft-ietf-manet-dlep-15
Abstract
When routing devices rely on modems to effect communications over
wireless links, they need timely and accurate knowledge of the
characteristics of the link (speed, state, etc.) in order to make
routing decisions. In mobile or other environments where these
characteristics change frequently, manual configurations or the
inference of state through routing or transport protocols does not
allow the router to make the best decisions. A bidirectional, eventdriven communication channel between the router and the modem is
necessary.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current InternetDrafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
This Internet-Draft will expire on January 7, 2016.
Ratliff, et al.
Expires January 7, 2016
[Page 1]
Internet-Draft
Dynamic Link Exchange Protocol (DLEP)
July 2015
Copyright Notice
Copyright (c) 2015 IETF Trust and the persons identified as the
document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust’s Legal
Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License.
Table of Contents
1.
Introduction . . . . . . . . . . . . . . .
1.1. Protocol Overview . . . . . . . . . . .
1.2. Requirements . . . . . . . . . . . . .
2. Assumptions . . . . . . . . . . . . . . . .
3. Core Features and Extensions . . . . . . .
3.1. Experiments . . . . . . . . . . . . . .
4. Metrics . . . . . . . . . . . . . . . . . .
4.1. Mandatory Metrics . . . . . . . . . . .
5. DLEP Session Flow . . . . . . . . . . . . .
5.1. Peer Discovery State . . . . . . . . .
5.2. Session Initialization State . . . . .
5.3. In-Session State . . . . . . . . . . .
5.4. Session Termination State . . . . . . .
6. DLEP Signal and Message Processing . . . .
7. DLEP Signal and Message Structure . . . . .
7.1. DLEP Signal Header . . . . . . . . . .
7.2. DLEP Message Header . . . . . . . . . .
7.3. DLEP Generic Data Item . . . . . . . .
8. DLEP Signals and Messages . . . . . . . . .
8.1. Peer Discovery Signal . . . . . . . . .
8.2. Peer Offer Signal . . . . . . . . . . .
8.3. Session Initialization Message . . . .
8.4. Session Initialization Response Message
8.5. Session Update Message . . . . . . . .
8.6. Session Update Response Message . . . .
8.7. Session Termination Message . . . . . .
8.8. Session Termination Response Message .
8.9. Destination Up Message . . . . . . . .
8.10. Destination Up Response Message . . . .
8.11. Destination Down Message . . . . . . .
8.12. Destination Down Response Message . . .
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Dynamic Link Exchange Protocol (DLEP)
8.13. Destination Update Message . . . . .
8.14. Heartbeat Message . . . . . . . . . .
8.15. Link Characteristics Request Message
8.16. Link Characteristics Response Message
9. DLEP Data Items . . . . . . . . . . . . .
9.1. Status . . . . . . . . . . . . . . .
9.2. IPv4 Connection Point . . . . . . . .
9.3. IPv6 Connection Point . . . . . . . .
9.4. Peer Type . . . . . . . . . . . . . .
9.5. Heartbeat Interval . . . . . . . . .
9.6. Extensions Supported . . . . . . . .
9.7. MAC Address . . . . . . . . . . . . .
9.8. IPv4 Address . . . . . . . . . . . .
9.9. IPv6 Address . . . . . . . . . . . .
9.10. IPv4 Attached Subnet . . . . . . . .
9.11. IPv6 Attached Subnet . . . . . . . .
9.12. Maximum Data Rate (Receive) . . . . .
9.13. Maximum Data Rate (Transmit) . . . .
9.14. Current Data Rate (Receive) . . . . .
9.15. Current Data Rate (Transmit) . . . .
9.16. Latency . . . . . . . . . . . . . . .
9.17. Resources (Receive) . . . . . . . . .
9.18. Resources (Transmit) . . . . . . . .
9.19. Relative Link Quality (Receive) . . .
9.20. Relative Link Quality (Transmit) . .
9.21. Link Characteristics Response Timer .
10. Credit-Windowing . . . . . . . . . . . .
10.1. Credit-Windowing Messages . . . . .
10.1.1. Destination Up Message . . . . .
10.1.2. Destination Up Response Message
10.1.3. Destination Update Message . . .
10.2. Credit-Windowing Data Items . . . .
10.2.1. Credit Grant . . . . . . . . . .
10.2.2. Credit Window Status . . . . . .
10.2.3. Credit Request . . . . . . . . .
11. Security Considerations . . . . . . . . .
12. IANA Considerations . . . . . . . . . . .
12.1. Registrations . . . . . . . . . . .
12.2. Expert Review: Evaluation Guidelines
12.3. Signal/Message Type Registration . .
12.4. DLEP Data Item Registrations . . . .
12.5. DLEP Status Code Registrations . . .
12.6. DLEP Extensions Registrations . . .
12.7. DLEP Well-known Port . . . . . . . .
12.8. DLEP Multicast Address . . . . . . .
13. Acknowledgements . . . . . . . . . . . .
14. References . . . . . . . . . . . . . . .
14.1. Normative References . . . . . . . .
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[Page 3]
Internet-Draft
Dynamic Link Exchange Protocol (DLEP)
14.2. Informative References . . . . . . . .
Appendix A. Discovery Signal Flows . . . . . .
Appendix B. Peer Level Message Flows . . . . .
B.1. Session Initialization . . . . . . . .
B.2. Session Initialization - Refused . . .
B.3. Router Changes IP Addresses . . . . . .
B.4. Modem Changes Session-wide Metrics . .
B.5. Router Terminates Session . . . . . . .
B.6. Modem Terminates Session . . . . . . .
B.7. Session Heartbeats . . . . . . . . . .
B.8. Router Detects a Heartbeat timeout . .
B.9. Modem Detects a Heartbeat timeout . . .
Appendix C. Destination Specific Signal Flows
C.1. Common Destination Signaling . . . . .
C.2. Multicast Destination Signaling . . . .
C.3. Link Characteristics Request . . . . .
Authors’ Addresses . . . . . . . . . . . . . .
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Introduction
There exist today a collection of modem devices that control links of
variable datarate and quality. Examples of these types of links
include line-of-sight (LOS) terrestrial radios, satellite terminals,
and cable/DSL modems. Fluctuations in speed and quality of these
links can occur due to configuration, or on a moment-to-moment basis,
due to physical phenomena like multipath interference, obstructions,
rain fade, etc. It is also quite possible that link quality and
datarate vary with respect to individual destinations on a link, and
with the type of traffic being sent. As an example, consider the
case of an 802.11 access point, serving 2 associated laptop
computers. In this environment, the answer to the question "What is
the datarate on the 802.11 link?" is "It depends on which associated
laptop we’re talking about, and on what kind of traffic is being
sent." While the first laptop, being physically close to the access
point, may have a datarate of 54Mbps for unicast traffic, the other
laptop, being relatively far away, or obstructed by some object, can
simultaneously have a datarate of only 32Mbps for unicast. However,
for multicast traffic sent from the access point, all traffic is sent
at the base transmission rate (which is configurable, but depending
on the model of the access point, is usually 24Mbps or less).
In addition to utilizing variable datarate links, mobile networks are
challenged by the notion that link connectivity will come and go over
time, without an effect on a router’s interface state (Up or Down).
Effectively utilizing a relatively short-lived connection is
problematic in IP routed networks, as routing protocols tend to rely
on interface state and independent timers at OSI Layer 3 to maintain
network convergence (e.g., HELLO messages and/or recognition of DEAD
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routing adjacencies). These dynamic connections can be better
utilized with an event-driven paradigm, where acquisition of a new
neighbor (or loss of an existing one) is signaled, as opposed to a
paradigm driven by timers and/or interface state.
Another complicating factor for mobile networks are the different
methods of physically connecting the modem devices to the router.
Modems can be deployed as an interface card in a router’s chassis, or
as a standalone device connected to the router via Ethernet or serial
link. In the case of Ethernet attachment, with existing protocols
and techniques, routing software cannot be aware of convergence
events occurring on the radio link (e.g., acquisition or loss of a
potential routing neighbor), nor can the router be aware of the
actual capacity of the link. This lack of awareness, along with the
variability in datarate, leads to a situation where finding the
(current) best route through the network to a given destination is
difficult to establish and properly maintain. This is especially
true of demand-based access schemes such as Demand Assigned Multiple
Access (DAMA) implementations used on some satellite systems. With a
DAMA-based system, additional datarate may be available, but will not
be used unless the network devices emit traffic at a rate higher than
the currently established rate. Increasing the traffic rate does not
guarantee additional datarate will be allocated; rather, it may
result in data loss and additional retransmissions on the link.
Addressing the challenges listed above, the co-authors have developed
the Dynamic Link Exchange Protocol, or DLEP. The DLEP protocol runs
between a router and its attached modem devices, allowing the modem
to communicate link characteristics as they change, and convergence
events (acquisition and loss of potential routing destinations). The
following diagrams are used to illustrate the scope of DLEP packets.
|-------Local Node-------|
|-------Remote Node------|
|
|
|
|
+--------+
+-------+
+-------+
+--------+
| Router |=======| Modem |{˜˜˜˜˜˜˜˜}| Modem |=======| Router |
|
|
| Device|
| Device|
|
|
+--------+
+-------+
+-------+
+--------+
|
|
| Link
|
|
|
|-DLEP--|
| Protocol |
|-DLEP--|
|
|
| (e.g.
|
|
|
|
|
| 802.11) |
|
|
Figure 1: DLEP Network
In Figure 1, when the local modem detects the presence of a remote
node, it (the local modem) sends a message to its router via the DLEP
protocol. The message consists of an indication of what change has
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occurred on the link (e.g., presence of a remote node detected),
along with a collection of DLEP-defined Data Items that further
describe the change. Upon receipt of the message, the local router
may take whatever action it deems appropriate, such as initiating
discovery protocols, and/or issuing HELLO messages to converge the
network. On a continuing, as-needed basis, the modem devices use
DLEP to report any characteristics of the link (datarate, latency,
etc.) that have changed. DLEP is independent of the link type and
topology supported by the modem. Note that the DLEP protocol is
specified to run only on the local link between router and modem.
Some over the air signaling may be necessary between the local and
remote modem in order to provide some parameters in DLEP messages
between the local modem and local router, but DLEP does not specify
how such over the air signaling is carried out. Over the air
signaling is purely a matter for the modem implementer.
Figure 2 shows how DLEP can support a configuration where routers are
connected with different link types. In this example, Modem A
implements a point-to-point link, and Modem B is connected via a
shared medium. In both cases, the DLEP protocol is used to report
the characteristics of the link (datarate, latency, etc.) to routers.
The modem is also able to use the DLEP session to notify the router
when the remote node is lost, shortening the time required to reconverge the network.
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+--------+
+----+ Modem A|
|
| Device | <===== // ======>
|
+--------+
P-2-P Link
+---+----+
| Router |
|
|
+---+----+
|
+--------+
+-----+ Modem B|
| Device |
o o o o o o o o
+--------+
o Shared
o
o Medium o
o
o
o
o
o
o
o
+--------+
| Modem B|
| Device |
+---+----+
|
|
+---+----+
| Router |
|
|
+--------+
July 2015
+--------+
| Modem A+---+
| Device |
|
+--------+
|
+---+----+
| Router |
|
|
+---+----+
+--------+ |
| Modem B| |
| Device +--+
+--------+
Figure 2: DLEP Network with Multiple Modem Devices
1.1.
Protocol Overview
As mentioned earlier, DLEP defines a set of messages used by modems
and their attached routers. The messages are used to communicate
events that occur on the physical link(s) managed by the modem: for
example, a remote node entering or leaving the network, or that the
link has changed. Associated with these messages are a set of data
items - information that describes the remote node (e.g., address
information), and/or the characteristics of the link to the remote
node.
The protocol is defined as a collection of type-length-value (TLV)
based formats, specifying the messages that are exchanged between a
router and a modem, and the data items associated with the message.
This document specifies transport of DLEP messages and data items via
the TCP transport, with a UDP-based discovery mechanism. Other
transports for the protocol are possible, but are outside the scope
of this document.
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DLEP uses a session-oriented paradigm between the modem device and
its associated router. If multiple modem devices are attached to a
router (as in Figure 2), or the modem supports multiple connections
(via multiple logical or physical interfaces), then separate DLEP
sessions exist for each modem or connection. This router/modem
session provides a carrier for information exchange concerning
’destinations’ that are available via the modem device. A
’destination’ can be either physical (as in the case of a specific
far-end router), or a logical destination (as in a Multicast group).
As such, all of the destination-level exchanges in DLEP can be
envisioned as building an information base concerning the remote
nodes, and the link characteristics to those nodes.
Multicast traffic destined for the variable-quality network (the
network accessed via the DLEP modem) is handled in IP networks by
deriving a Layer 2 MAC address based on the Layer 3 address.
Leveraging on this scheme, multicast traffic is supported in DLEP
simply by treating the derived MAC address as any other ’destination’
(albeit a logical one) in the network. To support these logical
destinations, one of the DLEP participants (typically, the router)
informs the other as to the existence of the logical destination.
The modem, once it is aware of the existence of this logical
destination, reports link characteristics just as it would for any
other destination in the network. The specific algorithms a modem
would use to derive metrics on multicast (or logical) destinations
are outside the scope of this specification, and is left to specific
implementations to decide.
1.2.
Requirements
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP
14, RFC 2119 [RFC2119].
2.
Assumptions
Routers and modems that exist as part of the same node (e.g., that
are locally connected) can use a discovery technique to locate each
other, thus avoiding a priori configuration. The router is
responsible for initializing the discovery process, using the Peer
Discovery signal (Section 8.1).
DLEP uses a session-oriented paradigm. A router and modem form a
session by completing the discovery and initialization process. This
router-modem session persists unless or until it either (1) times
out, based on the timeout values supplied, or (2) is explicitly torn
down by one of the participants. Note that while use of timers in
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DLEP is optional, it is strongly RECOMMENDED that implementations
choose to run with timers enabled.
DLEP assumes that the MAC address for delivering data traffic is the
MAC specified in the Destination Up message (Section 8.9). No
manipulation or substitution is performed; the MAC address supplied
in Destination Up is used as the OSI Layer 2 Destination MAC address.
DLEP also assumes that MAC addresses MUST be unique within the
context of a router-modem session. Additionally, DLEP can support
MAC addresses in either EUI-48 or EUI-64 format, with the restriction
that ALL MAC addresses for a given DLEP session MUST be in the same
format, and MUST be consistent with the MAC address format of the
connected modem (e.g., if the modem is connected to the router with
an EUI-48 MAC, all destination addresses via that modem MUST be
expressed in EUI-48 format).
DLEP uses UDP multicast for single-hop discovery signalling, and TCP
for transport of the control messages. Therefore, DLEP assumes that
the modem and router have topologically consistent IP addresses
assigned. It is RECOMMENDED that DLEP implementations utilize IPv6
link-local addresses to reduce the administrative burden of address
assignment.
Destinations can be identified by either the router or the modem, and
represent a specific destination (e.g., an address) that exists on
the link(s) managed by the modem. A destination MUST contain a MAC
address, it MAY optionally include a Layer 3 address (or addresses).
Note that since a destination is a MAC address, the MAC could
reference a logical destination, as in a derived multicast MAC
address, as well as a physical device. As destinations are
discovered, DLEP routers and modems build an information base on
destinations accessible via the modem.
The DLEP messages concerning destinations thus become the way for
routers and modems to maintain, and notify each other about, an
information base representing the physical and logical (e.g.,
multicast) destinations accessible via the modem device. The
information base would contain addressing information (i.e. MAC
address, and OPTIONALLY, Layer 3 addresses), link characteristics
(metrics), and OPTIONALLY, flow control information (credits).
DLEP assumes that any message not understood by a receiver MUST
result in an error indication being sent to the originator, and also
MUST result in termination of the session between the DLEP peers.
Any DLEP data item not understood by a receiver MUST also result in
termination of the session.
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DLEP assumes that security on the session (e.g., authentication of
session partners, encryption of traffic, or both) is dealt with by
the underlying transport mechanism (e.g., by using a transport such
as TLS [RFC5246]).
This document specifies an implementation of the DLEP messages
running over the TCP transport. It is assumed that DLEP running over
other transport mechanisms would be documented separately.
3.
Core Features and Extensions
DLEP has a core set of signals, messages and data items that MUST be
parsed without error by an implementation in order to guarantee
interoperability and therefore make the implementation DLEP
compliant. This document defines this set of signals, messages and
data items, listing them as ’core’. It should be noted that some
core signals, messages and data items might not be used during the
lifetime of a single DLEP session, but a compliant implementation
MUST support them.
While this document represents the best efforts of the working group
to be functionally complete, it is recognized that extensions to DLEP
will in all likelihood be necessary as more link types are used.
If interoperable protocol extensions are required, they MUST be
standardized either as an update to this document, or as an
additional stand-alone specification. The requests for IANAcontrolled registries in this document contain sufficient Reserved
space, in terms of DLEP signals, messages, data items and status
codes, to accommodate future extensions to the protocol and the data
transferred.
All extensions are considered OPTIONAL. Extensions may be negotiated
on a per-session basis during session initialization via the
Extensions Supported mechanism. Only the DLEP functionality listed
as ’core’ is required by an implementation in order to be DLEP
compliant.
This specification defines one extension, Credit Windowing, that
devices MAY choose to implement.
3.1.
Experiments
This document requests Private Use numbering space in the DLEP
signal/message, data item and status code registries for experimental
items. The intent is to allow for experimentation with new signals,
messages, data items, and/or status codes, while still retaining the
documented DLEP behavior.
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Use of the experimental signals, messages, data items, status codes,
or behaviors MUST be announced as Extensions, using extension
identifiers from the Private Use space in the Extensions Supported
registry (Table 4), during session initialization with a value agreed
upon (a priori) between the participating peers.
Multiple experiments MAY be announced in the Session Initialization
messages. However, use of multiple experiments in a single session
could lead to interoperability issues or unexpected results (e.g.,
clashes of experimental signals, messages, data items and/or status
code types), and is therefore discouraged. It is left to
implementations to determine the correct processing path (e.g., a
decision on whether to terminate the session, or to establish a
precedence of the conflicting definitions) if such conflicts arise.
4.
Metrics
DLEP includes the ability for the router and modem to communicate
metrics that reflect the characteristics (e.g., datarate, latency) of
the variable-quality link in use. DLEP does not specify how a given
metric value is to be calculated, rather, the protocol assumes that
metrics have been calculated with a ’best effort’, incorporating all
pertinent data that is available to the modem device.
DLEP allows for metrics to be sent within two contexts - metrics for
a specific destination within the network (e.g., a specific router),
and per-session (those that apply to all destinations accessed via
the modem). Most metrics can be further subdivided into transmit and
receive metrics. In cases where metrics are provided at session
level, the receiver MUST propagate the metrics to all entries in its
information base for destinations that are accessed via the
originator.
DLEP modem implementations MUST announce all metric items that will
be reported during the session, and provide default values for those
metrics, in the Session Initialization Response message
(Section 8.4). In order to use a metric type that was not included
in the Session Initialization Response message, modem implementations
MUST terminate the session with the router (via the Session Terminate
message (Section 8.7)), and establish a new session.
It is left to implementations to choose sensible default values based
on their specific characteristics. Modems having static (nonchanging) link metric characteristics MAY report metrics only once
for a given destination (or once on a modem-wide basis, if all
connections via the modem are of this static nature).
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A DLEP participant MAY send metrics both in a session context (via
the Session Update message) and a specific destination context (via
Destination Update) at any time. The heuristics for applying
received metrics is left to implementations.
4.1.
Mandatory Metrics
As mentioned above, DLEP modem implementations MUST announce all
supported metric items during the Session Initialization state.
However, a modem MUST include the following list of metrics in the
Session Initialization Response message (Section 8.4):
o
Maximum Data Rate (Receive) (Section 9.12)
o
Maximum Data Rate (Transmit) (Section 9.13)
o
Current Data Rate (Receive) (Section 9.14)
o
Current Data Rate (Transmit) (Section 9.15)
o
Latency (Section 9.16)
5.
DLEP Session Flow
All DLEP peers transition through four (4) distinct states during the
lifetime of a DLEP session:
o
Peer Discovery
o
Session Initialization
o
In-Session
o
Session Termination
The Peer Discovery state is OPTIONAL to implement for routers. If it
is used, this state is the initial state. If it is not used, then
one or more preconfigured address/port combinations SHOULD be
provided to the router, and the device starts in the Session
Initialization state.
Modems MUST support the Peer Discovery state.
5.1.
Peer Discovery State
In the Peer Discovery state, routers send UDP packets containing a
Peer Discovery signal (Section 8.1) to the DLEP well-known multicast
address (Section 12.8) and port number (Section 12.7) then await a
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unicast UDP packet containing a Peer Offer signal (Section 8.2) from
a modem. While in the Peer Discovery state, Peer Discovery signals
MUST be sent repeatedly by a router, at regular intervals; every
three (3) seconds is RECOMMENDED.
In the Peer Discovery state, the modem waits for incoming Peer
Discovery signals on the DLEP well-known multicast address and port.
On receipt of a valid signal, it MUST unicast a Peer Offer signal to
the source address of the received UDP packet. Peer Offer signals
MAY contain the unicast address and port for TCP-based communication
with a modem, via the IPv4 Connection Point data item (Section 9.2)
or the IPv6 Connection Point data item (Section 9.3), on which it is
prepared to accept an incoming TCP connection. The modem then begins
listening for incoming TCP connections, and, having accepted one,
enters the Session Initialization state. Anything other than Peer
Discovery signals received on the UDP socket MUST be silently
dropped.
Modems SHOULD be prepared to accept a TCP connection from a router
that is not using the Discovery mechanism, i.e. a connection attempt
that occurs without a preceeding Peer Discovery signal. The modem
MUST accept a TCP connection on only one (1) address/port combination
per session.
Routers MUST use one or more of the modem address/port combinations
from the Peer Offer signal or from a priori configuration to
establish a new TCP connection to the modem. If more than one modem
address/port combinations is available, router implementations MAY
use their own heuristics to determine the order in which they are
tried. If a TCP connection cannot be achieved using any of the
address/port combinations and the Discovery mechanism is in use, then
the router SHOULD resume issuing Peer Discovery signals. If no IP
Connection Point data items are included in the Peer Offer signal,
the router MUST use the origin address of the signal as the IP
address, and the DLEP well-known port number.
Once a TCP connection has been established with the modem, the router
begins a new session and enters the Session Initialization state. It
is up to the router implementation if Peer Discovery signals continue
to be sent after the device has transitioned to the Session
Initialization state.
5.2.
Session Initialization State
On entering the Session Initialization state, the router MUST send a
Session Initialization message (Section 8.3) to the modem. The
router MUST then wait for receipt of a Session Initialization
Response message (Section 8.4) from the modem. Receipt of the
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Session Initialization Response message containing a Status data item
(Section 9.1) with value ’Success’, see Table 3, indicates that the
modem has received and processed the Session Initialization message,
and the router MUST transition to the In-Session state.
On entering the Session Initialization state, the modem MUST wait for
receipt of a Session Initialization message from the router. Upon
receipt and successful parsing of a Session Initialization message,
the modem MUST send a Session Initialization Response message, and
the session MUST transition to the In-Session state.
As mentioned before, DLEP provides an extension negotiation
capability to be used in the Session Initialization state.
Extensions supported by an implementation MUST be declared to
potential DLEP peers using the Extensions Supported data item
(Section 9.6).
Once both peers have exchanged initialization messages, an
implementation MUST NOT emit any message, signal, data item or status
code associated with an extension that was not specified in the
received initialization message from its peer.
If the router receives any message other than a valid Session
Initialization Response, it MUST send a Session Termination message
(Section 8.7) with a relevant status code, e.g. ’Unexpected
Message’, see Table 3, and transition to the Session Termination
state.
If the modem receives any message other than Session Initialization,
or it fails to parse the received message, it MUST NOT send any
message, and MUST terminate the TCP connection, then restart at the
Peer Discovery state.
As mentioned before, the Session Initialization Response message MUST
contain metric data items for ALL metrics that will be used during
the session. If an additional metric is to be introduced after the
session has started, the session between router and modem MUST be
terminated and restarted, and the new metric described in the next
Session Initialization Response message.
5.3.
In-Session State
In the In-Session state, messages can flow in both directions between
peers, indicating changes to the session state, the arrival or
departure of reachable destinations, or changes of the state of the
links to the destinations.
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In order to maintain the In-Session state, periodic Heartbeat
messages (Section 8.14) MAY be exchanged between router and modem.
These messages are intended to keep the session alive, and to verify
bidirectional connectivity between the two participants. Each DLEP
peer is responsible for the creation of heartbeat messages. Receipt
of any valid DLEP message MUST reset the heartbeat interval timer
(i.e., valid DLEP messages take the place of, and obviate the need
for, Heartbeat messages).
DLEP provides a Session Update message (Section 8.5), intended to
communicate some change in status (e.g., a change of layer 3 address
parameters, or a modem-wide link change).
In addition to the session messages, the participants will transmit
messages concerning destinations in the network. These messages
trigger creation/maintenance/deletion of destinations in the
information base of the recipient. For example, a modem will inform
its attached router of the presence of a new destination via the
Destination Up message (Section 8.9). Receipt of a Destination Up
causes the router to allocate the necessary resources, creating an
entry in the information base with the specifics (i.e. MAC Address,
Latency, Data Rate, etc.) of the destination. The loss of a
destination is communicated via the Destination Down message
(Section 8.11), and changes in status to the destination (e.g.,
varying link quality, or addressing changes) are communicated via the
Destination Update message (Section 8.13). The information on a
given destination will persist in the router’s information base until
(1) a Destination Down message is received, indicating that the modem
has lost contact with the remote node, or (2) the router/modem
transitions to the Session Termination state.
In addition to receiving metrics about the link, DLEP provides a
message allowing a router to request a different datarate, or
latency, from the modem. This message is referred to as the Link
Characteristics Request message (Section 8.15), and gives the router
the ability to deal with requisite increases (or decreases) of
allocated datarate/latency in demand-based schemes in a more
deterministic manner.
The In-Session state is maintained until one of the following
conditions occur:
o
The implementation terminates the session by sending a Session
Termination message (Section 8.7)), or
o
The DLEP peer terminates the session, indicated by receiving a
Session termination message.
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The implementation MUST then transition to the Session Termination
state.
5.4.
Session Termination State
When a DLEP implementation enters the Session Termination state after
sending a Session Termination message (Section 8.7) as the result of
an invalid message or error, it MUST wait for a Session Termination
Response message (Section 8.8) from its peer. If Heartbeat messages
(Section 8.14) are in use, senders SHOULD allow four (4) heartbeat
intervals to expire before assuming that the peer is unresponsive,
and continuing with session termination. If Heartbeat messages are
not in use, then if is RECOMMENDED that an interval of eight (8)
seconds be used.
When a DLEP implementation enters the Session Termination state
having received a Session Termination message from its peer, it MUST
immediately send a Session Termination Response.
The sender and receiver of a Session Termination message MUST release
all resources allocated for the session, and MUST eliminate all
destinations in the information base accessible via the peer
represented by the session. No Destination Down messages
(Section 8.11) are sent.
Any messages received after either sending or receiving a Session
Termination message MUST be silently ignored.
Once Session Termination messages have been exchanged, or timed out,
the device MUST terminate the TCP connection to the peer, and return
to the relevant initial state.
6.
DLEP Signal and Message Processing
Most messages in DLEP are members of a request/response pair, e.g.
Destination Up message (Section 8.9), and Destination Up Response
message (Section 8.10). These pairs of messages define an implicit
transaction model for both session messages and destination messages.
As mentioned before, session message pairs control the flow of the
session through the various states, e.g. an implementation MUST NOT
leave the Session Initialization state until a Session Initialization
message (Section 8.3) and Session Initialization Response message
(Section 8.4) have been exchanged.
Destination message pairs describe the arrival and departure of
logical destinations, and control the flow of information about the
destinations in the several ways.
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Prior to the exchange of a pair of Destination Up and Destination Up
Response messages, no messages concerning the logical destination
identified by the MAC Address data item (Section 9.7) may be sent.
An implementation receiving a message with such an unannounced
destination MUST terminate the session by issuing a Session
Termination message (Section 8.7) with a status code of ’Invalid
Destination’, see Table 3, and transition to the Session Termination
state.
The receiver of a Destination Up message MAY decline further messages
concerning a given destination by sending a Destination Up Response
with a status code of ’Not Interested’, see Table 3. Receivers of
such responses MUST NOT send further messages concerning that
destination to the peer.
After exchanging a pair of Destination Down (Section 8.11) and
Destination Down Response (Section 8.12) messages, no messages
concerning the logical destination identified by the MAC Address data
item may be a sent without a previously sending a new Destination Up
message. An implementation receiving a message about a down
destination MUST terminate the session by issuing a Session
Termination message with a status code of ’Invalid Destination’ and
transition to the Session Termination state.
7.
DLEP Signal and Message Structure
DLEP defines two protocol units used in two different ways: Signals
and Messages. Signals are only used in the Discovery mechanism and
are carried in UDP datagrams. Messages are used bi-directionally
over a TCP connection between two peers, in the Session
Initialization, In-Session and Session Termination states.
Both signals and messages consist of a header followed by an
unordered list of data items. Headers consist of Type and Length
information, while data items are encoded as TLV (Type-Length-Value)
structures. In this document, the data items following a signal or
message header are described as being ’contained in’ the signal or
message.
There is no restriction on the order of data items following a
header, and the multiplicity of duplicate data items is defined by
the definition of the signal or message declared by the type in the
header.
All integers in header fields and values MUST be in network byteorder.
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DLEP Signal Header
The DLEP signal header contains the following fields:
0
1
2
3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
’D’
|
’L’
|
’E’
|
’P’
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Signal Type
| Length
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: DLEP Signal Header
"DLEP": Every signal MUST start with the characters: U+44, U+4C,
U+45, U+50.
Signal Type: An 16-bit unsigned integer containing one of the DLEP
Signal/Message Type values defined in this document.
Length: The length in octets, expressed as a 16-bit unsigned
integer, of all of the DLEP data items associated with this
signal. This length SHALL NOT include the length of the header
itself.
The DLEP signal header is immediately followed by one or more DLEP
data items, encoded in TLVs, as defined in this document.
If an unrecognized, or unexpected signal is received, or a received
signal contains unrecognized, invalid, or disallowed duplicate data
items, the receiving peer MUST ignore the signal.
7.2.
DLEP Message Header
The DLEP message header contains the following fields:
0
1
2
3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Message Type
| Length
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4: DLEP Message Header
Message Type: An 16-bit unsigned integer containing one of the DLEP
Signal/Message Type values defined in this document.
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Length: The length in octets, expressed as a 16-bit unsigned
integer, of all of the DLEP data items associated with this
message. This length SHALL NOT include the length of the header
itself.
The DLEP message header is immediately followed by one or more DLEP
data items, encoded in TLVs, as defined in this document.
If an unrecognized, or unexpected message is received, or a received
message contains unrecognized, invalid, or disallowed duplicate data
items, the receiving peer MUST issue a Session Termination message
(Section 8.7) with a Status data item (Section 9.1) containing the
most relevant status code, and transition to the Session Termination
state.
7.3.
DLEP Generic Data Item
All DLEP data items contain the following fields:
0
1
2
3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Data Item Type
| Length
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
Value...
:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 5: DLEP Generic Data Item
Data Item Type: An 16-bit unsigned integer field specifying the type
of data item being sent.
Length: The length in octets, expressed as an 16-bit unsigned
integer, of the value field of the data item. This length SHALL
NOT include the length of the header itself.
Value: A field of <Length> octets, which contains data specific to a
particular data item.
8.
DLEP Signals and Messages
As mentioned above, all DLEP signals begin with the DLEP signal
header, and all DLEP messages begin with the DLEP message header.
Therefore, in the following descriptions of specific signals and
messages, this header is assumed, and will not be replicated.
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Following is the set of core signals and messages that MUST be
recognized by a DLEP compliant implementation. As mentioned before,
not all messages may be used during a session, but an implementation
MUST correctly process these messages when received.
The core DLEP signals and messages are:
+-------------+-----------------------------------------------------+
| Type Code
| Description
|
+-------------+-----------------------------------------------------+
| 0
| Reserved
|
| 1
| Peer Discovery signal (Section 8.1)
|
| 2
| Peer Offer signal (Section 8.2)
|
| 3
| Session Initialization message (Section 8.3)
|
| 4
| Session Initialization Response message (Section
|
|
| 8.4)
|
| 5
| Session Update message (Section 8.5)
|
| 6
| Session Update Response message (Section 8.6)
|
| 7
| Session Termination message (Section 8.7)
|
| 8
| Session Termination Response message (Section 8.8) |
| 9
| Destination Up message (Section 8.9)
|
| 10
| Destination Up Response message (Section 8.10)
|
| 11
| Destination Down message (Section 8.11)
|
| 12
| Destination Down Response message (Section 8.12)
|
| 13
| Destination Update message (Section 8.13)
|
| 14
| Heartbeat message (Section 8.14)
|
| 15
| Link Characteristics Request message (Section 8.15) |
| 16
| Link Characteristics Response message (Section
|
|
| 8.16)
|
| 17-65519
| Reserved for future extensions
|
| 65520-65534 | Private Use. Available for experiments
|
| 65535
| Reserved
|
+-------------+-----------------------------------------------------+
Table 1: DLEP Signal/Message types
8.1.
Peer Discovery Signal
A Peer Discovery signal SHOULD be sent by a router to discover DLEP
modems in the network. The Peer Offer signal (Section 8.2) is
required to complete the discovery process. Implementations MAY
implement their own retry heuristics in cases where it is determined
the Peer Discovery signal has timed out.
To construct a Peer Discovery signal, the Signal Type value in the
signal header is set to 1, from Table 1.
The Peer Discovery signal MAY contain the following data item:
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Peer Type (Section 9.4)
Peer Offer Signal
A Peer Offer signal MUST be sent by a DLEP modem in response to a
valid Peer Discovery signal (Section 8.1).
The Peer Offer signal MUST be sent to the unicast address of the
originator of the Peer Discovery signal.
To construct a Peer Offer signal, the Signal Type value in the signal
header is set to 2, from Table 1.
The Peer Offer signal MAY contain the following data item:
o
Peer Type (Section 9.4)
The Peer Offer signal MAY contain one or more of any of the following
data items, with different values:
o
IPv4 Connection Point (Section 9.2)
o
IPv6 Connection Point (Section 9.3)
The IP Connection Point data items indicate the unicast address the
receiver of Peer Offer MUST use when connecting the DLEP TCP session.
If multiple IP Connection Point data items are present in the Peer
Offer signal, implementations MAY use their own heuristics to select
the address to connect to. If no IP Connection Point data items are
included in the Peer Offer signal, the receiver MUST use the origin
address of the signal as the IP address, and the DLEP well-known port
number (Section 12.7) to establish the TCP connection.
8.3.
Session Initialization Message
A Session Initialization message MUST be sent by a router as the
first message of the DLEP TCP session. It is sent by the router
after a TCP connect to an address/port combination that was obtained
either via receipt of a Peer Offer, or from a priori configuration.
If any optional extensions are supported by the implementation, they
MUST be enumerated in the Extensions Supported data item. If an
Extensions Supported data item does not exist in a Session
Initialization message, the receiver of the message MUST conclude
that there is no support for extensions in the sender.
Implementations supporting the Heartbeat Interval (Section 9.5)
should understand that heartbeats are not fully established until
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receipt of Session Initialization Response message (Section 8.4), and
should therefore implement their own timeout and retry heuristics for
this message.
To construct a Session Initialization message, the Message Type value
in the message header is set to 3, from Table 1.
The Session Initialization message MUST contain one of each of the
following data items:
o
Heartbeat Interval (Section 9.5)
The Session Initialization message MAY contain one of each of the
following data items:
o
Peer Type (Section 9.4)
o
Extensions Supported (Section 9.6)
A Session Initialization message MUST be acknowledged by the receiver
issuing a Session Initialization Response message (Section 8.4).
8.4.
Session Initialization Response Message
A Session Initialization Response message MUST be sent in response to
a received Session Initialization message (Section 8.3). The Session
Initialization Response message completes the DLEP session
establishment; the sender of the message should transition to the InSession state when the message is sent, and the receiver should
transition to the In-Session state upon receipt (and successful
parsing) of an acceptable Session Initialization Response message.
All supported metric data items MUST be included in the Session
Initialization Response message, with default values to be used on a
’modem-wide’ basis. This can be viewed as the modem ’declaring’ all
supported metrics at DLEP session initialization. Receipt of any
DLEP message containing a metric data item not included in the
Session Initialization Response message MUST be treated as an error,
resulting in the termination of the DLEP session between router and
modem.
If any optional extensions are supported by the modem, they MUST be
enumerated in the Extensions Supported data item. If an Extensions
Supported data item does not exist in a Session Initialization
Response message, the receiver of the message MUST conclude that
there is no support for extensions in the sender.
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After the Session Initialization/Session Initialization Response
messages have been successfully exchanged, implementations MUST only
use extensions that are supported by BOTH peers.
To construct a Session Initialization Response message, the Message
Type value in the message header is set to 4, from Table 1.
The Session Initialization Response message MUST contain one of each
of the following data items:
o
Heartbeat Interval (Section 9.5)
o
Maximum Data Rate (Receive) (Section 9.12)
o
Maximum Data Rate (Transmit) (Section 9.13)
o
Current Data Rate (Receive) (Section 9.14)
o
Current Data Rate (Transmit) (Section 9.15)
o
Latency (Section 9.16)
The Session Initialization Response message MUST contain one of each
of the following data items, if the data item will be used during the
lifetime of the session:
o
Resources (Receive) (Section 9.17)
o
Resources (Transmit) (Section 9.18)
o
Relative Link Quality (Receive) (Section 9.19)
o
Relative Link Quality (Transmit) (Section 9.20)
The Session Initialization Response message MAY contain one of each
of the following data items:
o
Status (Section 9.1)
o
Peer Type (Section 9.4)
o
Extensions Supported (Section 9.6)
A receiver of a Session Initialization Response message without a
Status data item MUST behave as if a Status data item with code
’Success’ had been received.
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Session Update Message
A Session Update message MAY be sent by a DLEP peer to indicate local
Layer 3 address changes, or metric changes on a modem-wide basis.
For example, addition of an IPv4 address to the router MAY prompt a
Session Update message to its attached DLEP modems. Also, for
example, a modem that changes its Maximum Data Rate (Receive) for all
destinations MAY reflect that change via a Session Update message to
its attached router(s).
Concerning Layer 3 addresses, if the modem is capable of
understanding and forwarding this information (via proprietary
mechanisms), the address update would prompt any remote DLEP modems
(DLEP-enabled modems in a remote node) to issue a Destination Update
message (Section 8.13) to their local routers with the new (or
deleted) addresses. Modems that do not track Layer 3 addresses
SHOULD silently parse and ignore Layer 3 data items. The Session
Update message MUST be acknowledged with a Session Update Response
message (Section 8.6).
If metrics are supplied with the Session Update message (e.g.,
Maximum Data Rate), these metrics are considered to be modem-wide,
and therefore MUST be applied to all destinations in the information
base associated with the router/modem session.
Supporting implementations are free to employ heuristics to
retransmit Session Update messages. The sending of Session Update
messages for Layer 3 address changes SHOULD cease when either
participant (router or modem) determines that the other
implementation does not support Layer 3 address tracking.
To construct a Session Update message, the Message Type value in the
message header is set to 5, from Table 1.
The Session Update message MAY contain one of each of the following
data items:
o
Maximum Data Rate (Receive) (Section 9.12)
o
Maximum Data Rate (Transmit) (Section 9.13)
o
Current Data Rate (Receive) (Section 9.14)
o
Current Data Rate (Transmit) (Section 9.15)
o
Latency (Section 9.16)
o
Resources (Receive) (Section 9.17)
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o
Resources (Transmit) (Section 9.18)
o
Relative Link Quality (Receive) (Section 9.19)
o
Relative Link Quality (Transmit) (Section 9.20)
July 2015
The Session Update message MAY contain one or more of the following
data items, with different values:
o
IPv4 Address (Section 9.8)
o
IPv6 Address (Section 9.9)
A Session Update message MUST be acknowledged by the receiver issuing
a Session Update Response message (Section 8.6).
8.6.
Session Update Response Message
A Session Update Response message MUST be sent by implementations to
indicate whether a Session Update message (Section 8.5) was
successfully received.
To construct a Session Update Response message, the Message Type
value in the message header is set to 6, from Table 1.
The Session Update Response message MAY contain one of each of the
following data items:
o
Status (Section 9.1)
A receiver of a Session Update Response message without a Status data
item MUST behave as if a Status data item with code ’Success’ had
been received.
8.7.
Session Termination Message
A Session Termination message MUST be sent by a DLEP participant when
the router/modem session needs to be terminated.
To construct a Session Termination message, the Message Type value in
the message header is set to 7, from Table 1.
The Session Termination message MAY contain one of each of the
following data items:
o
Status (Section 9.1)
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A receiver of a Session Termination message without a Status data
item MUST behave as if a Status of ’Unknown reason for Session
Termination’ has been received.
A Session Termination message MUST be acknowledged by the receiver
issuing a Session Termination Response message (Section 8.8).
8.8.
Session Termination Response Message
A Session Termination Response message MUST be sent by a DLEP peer in
response to a received Session Termination message (Section 8.7).
Receipt of a Session Termination Response message completes the
teardown of the router/modem session.
To construct a Session Termination Response message, the Message Type
value in the message header is set to 8, from Table 1.
The Session Termination Response message MAY contain one of each of
the following data items:
o
Status (Section 9.1)
A receiver of a Session Termination Response message without a Status
data item MUST behave as if a Status data item with status code
’Success’, implying graceful termination, had been received.
8.9.
Destination Up Message
A Destination Up message can be sent either by the modem, to indicate
that a new remote node has been detected, or by the router, to
indicate the presence of a new logical destination (e.g., a Multicast
group) in the network.
A Destination Up message MUST be acknowledged by the receiver issuing
a Destination Up Response message (Section 8.10). The sender of the
Destination Up message is free to define its retry heuristics in
event of a timeout. When a Destination Up message is received and
successfully processed, the receiver should add knowledge of the new
destination to its information base, indicating that the destination
is accessible via the modem/router pair.
To construct a Destination Up message, the Message Type value in the
message header is set to 9, from Table 1.
The Destination Up message MUST contain one of each of the following
data items:
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MAC Address (Section 9.7)
The Destination Up message MAY contain one of each of the following
data items:
o
Maximum Data Rate (Receive) (Section 9.12)
o
Maximum Data Rate (Transmit) (Section 9.13)
o
Current Data Rate (Receive) (Section 9.14)
o
Current Data Rate (Transmit) (Section 9.15)
o
Latency (Section 9.16)
o
Resources (Receive) (Section 9.17)
o
Resources (Transmit) (Section 9.18)
o
Relative Link Quality (Receive) (Section 9.19)
o
Relative Link Quality (Transmit) (Section 9.20)
The Destination Up message MAY contain one or more of the following
data items, with different values:
o
IPv4 Address (Section 9.8)
o
IPv6 Address (Section 9.9)
o
IPv4 Attached Subnet (Section 9.10)
o
IPv6 Attached Subnet (Section 9.11)
If the sender has IPv4 and/or IPv6 address information for a
destination it SHOULD include the relevant data items in the
Destination Up message, reducing the need for the receiver to probe
for any address.
8.10.
Destination Up Response Message
A DLEP participant MUST send a Destination Up Response message to
indicate whether a Destination Up message (Section 8.9) was
successfully processed.
To construct a Destination Up Response message, the Message Type
value in the message header is set to 10, from Table 1.
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The Destination Up Response message MUST contain one of each of the
following data items:
o
MAC Address (Section 9.7)
The Destination Up Response message MAY contain one of each of the
following data items:
o
Status (Section 9.1)
A receiver of a Destination Up Response message without a Status data
item MUST behave as if a Status data item with status code ’Success’
had been received.
8.11.
Destination Down Message
A DLEP peer MUST send a Destination Down message to report when a
destination (a remote node or a multicast group) is no longer
reachable. A Destination Down Response message (Section 8.12) MUST
be sent by the recipient of a Destination Down message to confirm
that the relevant data has been removed from the information base.
The sender of the Destination Down message is free to define its
retry heuristics in event of a timeout.
To construct a Destination Down message, the Message Type value in
the message header is set to 11, from Table 1.
The Destination Down message MUST contain one of each of the
following data items:
o
8.12.
MAC Address (Section 9.7)
Destination Down Response Message
A DLEP participant MUST send a Destination Down Response message to
indicate whether a received Destination Down message (Section 8.11)
was successfully processed. If successfully processed, the sender of
the Response MUST have removed all entries in the information base
that pertain to the referenced destination.
To construct a Destination Down Response message, the Message Type
value in the message header is set to 12, from Table 1.
The Destination Down Response message MUST contain one of each of the
following data items:
o
MAC Address (Section 9.7)
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The Destination Down Response message MAY contain one of each of the
following data items:
o
Status (Section 9.1)
A receiver of a Destination Down Response message without a Status
data item MUST behave as if a Status data item with status code
’Success’ had been received.
8.13.
Destination Update Message
A DLEP participant SHOULD send the Destination Update message when it
detects some change in the information base for a given destination
(remote node or multicast group). Some examples of changes that
would prompt a Destination Update message are:
o
Change in link metrics (e.g., Data Rates)
o
Layer 3 addressing change
To construct a Destination Update message, the Message Type value in
the message header is set to 13, from Table 1.
The Destination Update message MUST contain one of each of the
following data items:
o
MAC Address (Section 9.7)
The Destination Update message MAY contain one of each of the
following data items:
o
Maximum Data Rate (Receive) (Section 9.12)
o
Maximum Data Rate (Transmit) (Section 9.13)
o
Current Data Rate (Receive) (Section 9.14)
o
Current Data Rate (Transmit) (Section 9.15)
o
Latency (Section 9.16)
o
Resources (Receive) (Section 9.17)
o
Resources (Transmit) (Section 9.18)
o
Relative Link Quality (Receive) (Section 9.19)
o
Relative Link Quality (Transmit) (Section 9.20)
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The Destination Update message MAY contain one or more of the
following data items, with different values:
o
IPv4 Address (Section 9.8)
o
IPv6 Address (Section 9.9)
8.14.
Heartbeat Message
A Heartbeat message SHOULD be sent by a DLEP participant every N
seconds, where N is defined in the Heartbeat Interval data item of
the Session Initialization message (Section 8.3) or Session
Initialization Response message (Section 8.4).
Note that implementations setting the Heartbeat Interval to 0
effectively sets the interval to an infinite value, therefore this
message SHOULD NOT be sent.
The message is used by participants to detect when a DLEP session
partner (either the modem or the router) is no longer communicating.
Participants SHOULD allow two (2) heartbeat intervals to expire with
no traffic on the router/modem session before initiating DLEP session
termination procedures.
To construct a Heartbeat message, the Message Type value in the
message header is set to 14, from Table 1.
There are no valid data items for the Heartbeat message.
8.15.
Link Characteristics Request Message
The Link Characteristics Request message MAY be sent by the router to
request that the modem initiate changes for specific characteristics
of the link. The request can reference either a real destination
(e.g., a remote node), or a logical destination (e.g., a multicast
group) within the network.
The Link Characteristics Request message MAY contain either a Current
Data Rate (CDRR or CDRT) data item to request a different datarate
than what is currently allocated, a Latency data item to request that
traffic delay on the link not exceed the specified value, or both. A
Link Characteristics Response message (Section 8.16) is required to
complete the request. Issuing a Link Characteristics Request with
ONLY the MAC Address data item is a mechanism a peer MAY use to
request metrics (via the Link Characteristics Response) from its
partner.
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The sender of a Link Characteristics Request message MAY attach a
timer to the request using the Link Characteristics Response Timer
data item. If a Link Characteristics Response message is received
after the timer expires, the sender MUST NOT assume that the request
succeeded. Implementations are free to define their retry heuristics
in event of a timeout.
To construct a Link Characteristics Request message, the Message Type
value in the message header is set to 15, from Table 1.
The Link Characteristics Request message MUST contain one of each of
the following data items:
o
MAC Address (Section 9.7)
The Link Characteristics Request message MAY contain one of each of
the following data items:
o
Link Characteristics Response Timer (Section 9.21)
o
Current Data Rate (Receive) (Section 9.14)
o
Current Data Rate (Transmit) (Section 9.15)
o
Latency (Section 9.16)
8.16.
Link Characteristics Response Message
A DLEP participant MUST send a Link Characteristics Response message
to indicate whether a received Link Characteristics Request message
(Section 8.15) was successfully processed. The Link Characteristics
Response message SHOULD contain a complete set of metric data items,
and MUST contain a full set (i.e. those declared in the Session
Initialization Response message (Section 8.4)), if metrics were
requested by only including a MAC address data item. It MUST contain
the same metric types as the request. The values in the metric data
items in the Link Characteristics Response message MUST reflect the
link characteristics after the request has been processed.
If an implementation is not able to alter the characteristics of the
link in the manner requested, then a Status data item with status
code ’Request Denied’, see Table 3, MUST be added to the message.
To construct a Link Characteristics Response message, the Message
Type value in the message header is set to 16, from Table 1.
The Link Characteristics Response message MUST contain one of each of
the following data items:
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MAC Address (Section 9.7)
The Link Characteristics Response message SHOULD contain one of each
of the following data items:
o
Maximum Data Rate (Receive) (Section 9.12)
o
Maximum Data Rate (Transmit) (Section 9.13)
o
Current Data Rate (Receive) (Section 9.14)
o
Current Data Rate (Transmit) (Section 9.15)
o
Latency (Section 9.16)
The Link Characteristics Response message MAY contain one of each of
the following data items:
o
Resources (Receive) (Section 9.17)
o
Resources (Transmit) (Section 9.18)
o
Relative Link Quality (Receive) (Section 9.19)
o
Relative Link Quality (Transmit) (Section 9.20)
o
Status (Section 9.1)
A receiver of a Link Characteristics Response message without a
Status data item MUST behave as if a Status data item with status
code ’Success’ had been received.
9.
DLEP Data Items
Following is the list of core data items that MUST be recognized by a
DLEP compliant implementation. As mentioned before, not all data
items need be used during a session, but an implementation MUST
correctly process these data items when correctly associated with a
signal or message.
The core DLEP data items are:
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+-------------+-----------------------------------------------------+
| Type Code
| Description
|
+-------------+-----------------------------------------------------+
| 0
| Reserved
|
| 1
| Status (Section 9.1)
|
| 2
| IPv4 Connection Point (Section 9.2)
|
| 3
| IPv6 Connection Point (Section 9.3)
|
| 4
| Peer Type (Section 9.4)
|
| 5
| Heartbeat Interval (Section 9.5)
|
| 6
| Extensions Supported (Section 9.6)
|
| 7
| MAC Address (Section 9.7)
|
| 8
| IPv4 Address (Section 9.8)
|
| 9
| IPv6 Address (Section 9.9)
|
| 10
| IPv4 Attached Subnet (Section 9.10)
|
| 11
| IPv6 Attached Subnet (Section 9.11)
|
| 12
| Maximum Data Rate (Receive) MDRR) (Section 9.12)
|
| 13
| Maximum Data Rate (Transmit) (MDRT) (Section 9.13) |
| 14
| Current Data Rate (Receive) (CDRR) (Section 9.14)
|
| 15
| Current Data Rate (Transmit) (CDRT) (Section 9.15) |
| 16
| Latency (Section 9.16)
|
| 17
| Resources (Receive) (RESR) (Section 9.17)
|
| 18
| Resources (Transmit) (REST) (Section 9.18)
|
| 19
| Relative Link Quality (Receive) (RLQR) (Section
|
|
| 9.19)
|
| 20
| Relative Link Quality (Transmit) (RLQT) (Section
|
|
| 9.20)
|
| 21
| Link Characteristics Response Timer (Section 9.21) |
| 22-24
| Credit Windowing (Section 10) extension data items |
| 25-65407
| Reserved for future extensions
|
| 65408-65534 | Private Use. Available for experiments
|
| 65535
| Reserved
|
+-------------+-----------------------------------------------------+
Table 2: DLEP Data Item types
9.1.
Status
The Status data item MAY appear in the Session Initialization
Response (Section 8.4), Session Termination (Section 8.7), Session
Termination Response (Section 8.8), Session Update Response
(Section 8.6), Destination Up Response (Section 8.10), Destination
Down Response (Section 8.12) and Link Characteristics Response
(Section 8.16) messages.
For the Session Termination message (Section 8.7), the Status data
item indicates a reason for the termination. For all acknowledgement
messages, the Status data item is used to indicate the success or
failure of the previously received message.
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The status data item includes an optional Text field that can be used
to provide a textual description of the status. The use of the Text
field is entirely up to the receiving implementation, i.e., it could
be output to a log file or discarded. If no Text field is supplied
with the Status data item, the Length field MUST be set to 1.
The Status data item contains the following fields:
0
1
2
3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Data Item Type
| Length
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Code
| Text...
:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Data Item Type:
Length:
TBD
1 + Length of text, in octets
Status Code:
One of the codes defined in Table 3 below.
Text: UTF-8 encoded string, describing the cause, used for
implementation defined purposes. Since this field is used for
description, implementations SHOULD limit characters in this field
to printable characters. Implementations receiving this data item
SHOULD check for printable characters in the field.
An implementation MUST NOT assume the Text field is NUL-terminated.
+-------------+---------+-----------+-------------------------------+
| Status Code | Value
| Failure
| Reason
|
|
|
| Mode
|
|
+-------------+---------+-----------+-------------------------------+
| Success
| 0
| Success
| The message was processed
|
|
|
|
| successfully.
|
| Unknown
| 1
| Terminate | The message was not
|
| Message
|
|
| recognized by the
|
|
|
|
| implementation.
|
| Unexpected | 2
| Terminate | The message was not expected |
| Message
|
|
| while the device was in the
|
|
|
|
| current state, e.g., a
|
|
|
|
| Session Initialization
|
|
|
|
| message (Section 8.3) in the |
|
|
|
| In-Session state.
|
| Invalid
| 3
| Terminate | One or more data items in the |
| Data
|
|
| message are invalid,
|
|
|
|
| unexpected or incorrectly
|
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|
|
|
| duplicated.
|
| Invalid
| 4
| Terminate | The destination provided in
|
| Destination |
|
| the message does not match a |
|
|
|
| previously announced
|
|
|
|
| destination. For example, in |
|
|
|
| the Link Characteristic
|
|
|
|
| Response message (Section
|
|
|
|
| 8.16).
|
| <Reserved> | 5-90
| Terminate | Reserved for future
|
|
|
|
| extensions.
|
| <Private
| 91-99
| Terminate | Available for experiments.
|
| Use>
|
|
|
|
| Not
| 100
| Continue | The receiver is not
|
| Interested |
|
| interested in this message
|
|
|
|
| subject, e.g. a Destination
|
|
|
|
| Up Response message (Section |
|
|
|
| 8.10) to indicate no further |
|
|
|
| messages about the
|
|
|
|
| destination.
|
| Request
| 101
| Continue | The receiver refuses to
|
| Denied
|
|
| complete the request.
|
| Timed Out
| 102
| Continue | The operation could not be
|
|
|
|
| completed in the time
|
|
|
|
| allowed.
|
| <Reserved> | 103-243 | Continue | Reserved for future
|
|
|
|
| extensions.
|
| <Private
| 244-254 | Continue | Available for experiments.
|
| Use>
|
|
|
|
| <Reserved> | 255
| Terminate | Reserved.
|
+-------------+---------+-----------+-------------------------------+
Table 3: DLEP Status Codes
A failure mode of ’Terminate’ indicates that the session MUST be
terminated after sending a response containing the status code. A
failure mode of ’Continue’ indicates that the session SHOULD continue
as normal.
9.2.
IPv4 Connection Point
The IPv4 Connection Point data item MAY appear in the Peer Offer
signal (Section 8.2).
The IPv4 Connection Point data item indicates the IPv4 address and,
optionally, the TCP port number on the DLEP modem available for
connections. If provided, the receiver MUST use this information to
perform the TCP connect to the DLEP server.
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The IPv4 Connection Point data item contains the following fields:
0
1
2
3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Data Item Type
| Length
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
IPv4 Address
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
TCP Port Number (optional) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Data Item Type:
Length:
TBD
4 (or 6 if TCP Port included)
IPv4 Address:
The IPv4 address listening on the DLEP modem.
TCP Port Number:
TCP Port number on the DLEP modem.
If the Length field is 6, the port number specified MUST be used to
establish the TCP session. If the TCP Port Number is omitted, i.e.
the Length field is 4, the receiver MUST use the DLEP well-known port
number (Section 12.7) to establish the TCP connection.
9.3.
IPv6 Connection Point
The IPv6 Connection Point data item MAY appear in the Peer Offer
signal (Section 8.2).
The IPv6 Connection Point data item indicates the IPv6 address and,
optionally, the TCP port number on the DLEP modem available for
connections. If provided, the receiver MUST use this information to
perform the TCP connect to the DLEP server.
The IPv6 Connection Point data item contains the following fields:
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0
1
2
3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Data Item Type
| Length
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
:
IPv6 Address
:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
:
IPv6 Address
:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
:
IPv6 Address
:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
:
IPv6 Address
:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
TCP Port Number (optional) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Data Item Type:
Length:
TBD
16 (or 18 if TCP Port included)
IPv6 Address:
The IPv6 address listening on the DLEP modem.
TCP Port Number:
TCP Port number on the DLEP modem.
If the Length field is 18, the port number specified MUST be used to
establish the TCP session. If the TCP Port Number is omitted, i.e.
the Length field is 16, the receiver MUST use the DLEP well-known
port number (Section 12.7) to establish the TCP connection.
9.4.
Peer Type
The Peer Type data item MAY appear in the Peer Discovery
(Section 8.1) and Peer Offer (Section 8.2) signals, and the Session
Initialization (Section 8.3) and Session Initialization Response
(Section 8.4) messages.
The Peer Type data item is used by the router and modem to give
additional information as to its type. The peer type is a string and
is envisioned to be used for informational purposes (e.g., as output
in a display command).
The Peer Type data item contains the following fields:
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0
1
2
3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Data Item Type
| Length
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Peer Type...
:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Data Item Type:
Length:
TBD
Length of peer type string, in octets.
Peer Type: UTF-8 encoded string. For example, a satellite modem
might set this variable to "Satellite terminal". Since this data
item is intended to provide additional information for display
commands, sending implementations SHOULD limit the data to
printable characters, and receiving implmentations SHOULD check
the data for printable characters.
An implementation MUST NOT assume the Peer Type field is NULterminated.
9.5.
Heartbeat Interval
The Heartbeat Interval data item MUST appear in both the Session
Initialization (Section 8.3) and Session Initialization Response
(Section 8.4) messages to indicate the Heartbeat timeout window to be
used by the sender.
The Interval is used to specify a period (in seconds) for Heartbeat
messages (Section 8.14). By specifying an Interval value of 0,
implementations MAY indicate the desire to disable Heartbeat messages
entirely (i.e., the Interval is set to an infinite value). However,
it is RECOMMENDED that implementations use non-0 timer values.
The Heartbeat Interval data item contains the following fields:
0
1
2
3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Data Item Type
| Length
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
Interval
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Data Item Type:
Length:
TBD
2
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Interval: 0 = Do not use heartbeats on this DLEP session.
= Interval, in seconds, for heartbeat messages.
9.6.
July 2015
Non-zero
Extensions Supported
The Extensions Supported data item MAY be used in both the Session
Initialization (Section 8.3) and Session Initialization Response
(Section 8.4) messages.
The Extensions Supported data item is used by the router and modem to
negotiate additional optional functionality they are willing to
support. The Extensions List is a concatenation of the types of each
supported extension, found in the IANA DLEP Extensions repository.
Each Extension Type definition includes which additional signals and
data-items are supported.
The Extensions Supported data item contains the following fields:
0
1
2
3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Data Item Type
| Length
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Extensions List...
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Data Item Type:
TBD
Length: Length of the extensions list in octets.
the number of extensions.
This is twice (2x)
Extension List: A list of extensions supported, identified by their
2-octet value as listed in the extensions registry.
9.7.
MAC Address
The MAC address data item MUST appear in all destination-oriented
messages (i.e., Destination Up (Section 8.9), Destination Up Response
(Section 8.10), Destination Down (Section 8.11), Destination Down
Response (Section 8.12), Destination Update (Section 8.13), Link
Characteristics Request (Section 8.15), and Link Characteristics
Response (Section 8.16)).
The MAC Address data item contains the address of the destination on
the remote node. The MAC address MAY be either a physical or a
virtual destination, and MAY be expressed in EUI-48 or EUI-64 format.
Examples of a virtual destination would be a multicast MAC address,
or the broadcast MAC (FF:FF:FF:FF:FF:FF).
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0
1
2
3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Data Item Type
| Length
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
MAC Address
:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
:
MAC Address
:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
:
MAC Address
:
(if EUI-64 used)
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Data Item Type:
Length:
6 for EUI-48 format, or 8 for EUI-64 format
MAC Address:
9.8.
TBD
MAC Address of the destination.
IPv4 Address
The IPv4 Address data item MAY appear in the Session Update
(Section 8.5), Destination Up (Section 8.9) and Destination Update
(Section 8.13) messages.
When included in Destination messages, this data item contains the
IPv4 address of the destination. When included in the Session Update
message, this data item contains the IPv4 address of the peer. In
either case, the data item also contains an indication of whether
this is a new or existing address, or is a deletion of a previously
known address.
The IPv4 Address data item contains the following fields:
0
1
2
3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Data Item Type
| Length
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Add/Drop
| IPv4 Address
:
| Indicator
|
:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
: IPv4
|
: Address
|
+-+-+-+-+-+-+-+-+
Data Item Type:
Length:
TBD
5
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Add/Drop: Value indicating whether this is a new or existing address
(1), or a withdrawal of an address (0). Values other than 0 or 1
MUST be considered as invalid.
IPv4 Address:
9.9.
The IPv4 address of the destination or peer.
IPv6 Address
The IPv6 Address data item MAY appear in the Session Update
(Section 8.5), Destination Up (Section 8.9) and Destination Update
(Section 8.13) messages. When included in Destination messages, this
data item contains the IPv6 address of the destination. When
included in the Session Update message, this data item contains the
IPv6 address of the peer. In either case, the data item also
contains an indication of whether this is a new or existing address,
or is a deletion of a previously known address.
The IPv6 Address data item contains the following fields:
0
1
2
3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Data Item Type
| Length
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
Add/Drop
| IPv6 Address
:
|
Indicator
|
:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
:
IPv6 Address
:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
:
IPv6 Address
:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
:
IPv6 Address
:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
: IPv6 Address |
+-+-+-+-+-+-+-+-+
Data Item Type:
Length:
TBD
17
Add/Drop: Value indicating whether this is a new or existing address
(1), or a withdrawal of an address (0). Values other than 0 or 1
MUST be considered as invalid.
IPv6 Address:
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9.10.
Dynamic Link Exchange Protocol (DLEP)
July 2015
IPv4 Attached Subnet
The DLEP IPv4 Attached Subnet allows a device to declare that it has
an IPv4 subnet (e.g., a stub network) attached, or that it has become
aware of an IPv4 subnet being present at a remote destination. The
IPv4 Attached Subnet data item MAY appear in the Destination Up
(Section 8.9) message. Once an IPv4 Subnet has been declared on a
device, the declaration SHALL NOT be withdrawn without withdrawing
the destination (via the Destination Down message (Section 8.11)) and
re-issuing the Destination Up message.
The DLEP IPv4 Attached Subnet data item contains the following
fields:
0
1
2
3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Data Item Type
| Length
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
IPv4 Attached Subnet
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Prefix Len.
|
+-+-+-+-+-+-+-+-+
Data Item Type:
Length:
TBD
5
IPv4 Subnet:
The IPv4 subnet reachable at the destination.
Prefix Length: Length of the prefix (1-32) for the IPv4 subnet. A
prefix length outside the speficied range MUST be considered as
invalid.
9.11.
IPv6 Attached Subnet
The DLEP IPv6 Attached Subnet allows a device to declare that it has
an IPv6 subnet (e.g., a stub network) attached, or that it has become
aware of an IPv6 subnet being present at a remote destination. The
IPv6 Attached Subnet data item MAY appear in the Destination Up
(Section 8.9) message. As in the case of the IPv4 attached Subnet
data item above, once an IPv6 attached subnet has been declared, it
SHALL NOT be withdrawn without withdrawing the destination (via the
Destination Down message (Section 8.11)) and re-issuing the
Destination Up message.
The DLEP IPv6 Attached Subnet data item contains the following
fields:
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0
1
2
3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Data Item Type
| Length
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
IPv6 Attached Subnet
:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
:
IPv6 Attached Subnet
:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
:
IPv6 Attached Subnet
:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
:
IPv6 Attached Subnet
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Prefix Len.
|
+-+-+-+-+-+-+-+-+
Data Item Type:
Length:
TBD
17
IPv4 Subnet:
The IPv6 subnet reachable at the destination.
Prefix Length: Length of the prefix (1-128) for the IPv6 subnet. A
prefix length outside the specified range MUST be considered as
invalid.
9.12.
Maximum Data Rate (Receive)
The Maximum Data Rate (Receive) (MDRR) data item MUST appear in the
Session Initialization Response message (Section 8.4), and MAY appear
in the Session Update (Section 8.5), Destination Up (Section 8.9),
Destination Update (Section 8.13) and Link Characteristics Response
(Section 8.16) messages to indicate the maximum theoretical data
rate, in bits per second, that can be achieved while receiving data
on the link.
The Maximum Data Rate (Receive) data item contains the following
fields:
0
1
2
3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Data Item Type
| Length
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
MDRR (bps)
:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
:
MDRR (bps)
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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Data Item Type:
Dynamic Link Exchange Protocol (DLEP)
Length:
July 2015
TBD
8
Maximum Data Rate (Receive): A 64-bit unsigned integer, representing
the maximum theoretical data rate, in bits per second (bps), that
can be achieved while receiving on the link.
9.13.
Maximum Data Rate (Transmit)
The Maximum Data Rate (Transmit) (MDRT) data item MUST appear in the
Session Initialization Response message (Section 8.4), and MAY appear
in the Session Update (Section 8.5), Destination Up (Section 8.9),
Destination Update (Section 8.13) and Link Characteristics Response
(Section 8.16) messages to indicate the maximum theoretical data
rate, in bits per second, that can be achieved while transmitting
data on the link.
The Maximum Data Rate (Transmit) data item contains the following
fields:
0
1
2
3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Data Item Type
| Length
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
MDRT (bps)
:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
:
MDRT (bps)
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Data Item Type:
Length:
TBD
8
Maximum Data Rate (Transmit): A 64-bit unsigned integer,
representing the maximum theoretical data rate, in bits per second
(bps), that can be achieved while transmitting on the link.
9.14.
Current Data Rate (Receive)
The Current Data Rate (Receive) (CDRR) data item MUST appear in the
Session Initialization Response message (Section 8.4), and MAY appear
in the Session Update (Section 8.5), Destination Up (Section 8.9),
Destination Update (Section 8.13) and Link Characteristics Response
(Section 8.16) messages to indicate the rate at which the link is
currently operating for receiving traffic.
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When used in the Link Characteristics Request message (Section 8.15),
CDRR represents the desired receive rate, in bits per second, on the
link.
The Current Data Rate (Receive) data item contains the following
fields:
0
1
2
3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Data Item Type
| Length
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
CDRR (bps)
:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
:
CDRR (bps)
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Data Item Type:
Length:
TBD
8
Current Data Rate (Receive): A 64-bit unsigned integer, representing
the current data rate, in bits per second, that can currently be
achieved while receiving traffic on the link.
If there is no distinction between current and maximum receive data
rates, current data rate receive MUST be set equal to the maximum
data rate receive.
9.15.
Current Data Rate (Transmit)
The Current Data Rate Transmit (CDRT) data item MUST appear in the
Session Initialization Response message (Section 8.4), and MAY appear
in the Session Update (Section 8.5), Destination Up (Section 8.9),
Destination Update (Section 8.13), and Link Characteristics Response
(Section 8.16) messages to indicate the rate at which the link is
currently operating for transmitting traffic.
When used in the Link Characteristics Request message (Section 8.15),
CDRT represents the desired transmit rate, in bits per second, on the
link.
The Current Data Rate (Transmit) data item contains the following
fields:
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0
1
2
3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Data Item Type
| Length
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
CDRT (bps)
:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
:
CDRT (bps)
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Data Item Type:
Length:
TBD
8
Current Data Rate (Transmit): A 64-bit unsigned integer,
representing the current data rate, in bits per second, that can
currently be achieved while transmitting traffic on the link.
If there is no distinction between current and maximum transmit data
rates, current data rate transmit MUST be set equal to the maximum
data rate transmit.
9.16.
Latency
The Latency data item MUST appear in the Session Initialization
Response message (Section 8.4), and MAY appear in the Session Update
(Section 8.5), Destination Up (Section 8.9), Destination Update
(Section 8.13), and Link Characteristics Response (Section 8.16)
messages to indicate the amount of latency, in microseconds, on the
link.
When used in the Link Characteristics Request message (Section 8.15),
Latency represents the maximum latency desired on the link.
The Latency value is reported as delay. The calculation of latency
is implementation dependent. For example, the latency may be a
running average calculated from the internal queuing.
0
1
2
3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Data Item Type
| Length
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
Latency
:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
:
Latency
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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Data Item Type:
Dynamic Link Exchange Protocol (DLEP)
Length:
July 2015
TBD
8
Latency: A 64-bit unsigned integer, representing the transmission
delay, in microseconds, that a packet encounters as it is
transmitted over the link.
9.17.
Resources (Receive)
The Resources (Receive) (RESR) data item MAY appear in the Session
Initialization Response message (Section 8.4), Session Update
(Section 8.5), Destination Up (Section 8.9), Destination Update
(Section 8.13) and Link Characteristics Response (Section 8.16)
messages to indicate the amount of resources for reception (with 0
meaning ’no resources available’, and 100 meaning ’all resources
available’) at the destination. The list of resources that might be
considered is beyond the scope of this document, and is left to
implementations to decide.
The Resources (Receive) data item contains the following fields:
0
1
2
3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Data Item Type
| Length
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
RESR
|
+-+-+-+-+-+-+-+-+
Data Item Type:
Length:
TBD
1
Resources (Receive): An 8-bit integer percentage, 0-100,
representing the amount of resources allocated to receiving data.
Any value greater than 100 MUST be considered as invalid.
If a device cannot calculate RESR, this data item SHOULD NOT be
issued.
9.18.
Resources (Transmit)
The Resources (Transmit) (REST) data item MAY appear in the Session
Initialization Response message (Section 8.4), Session Update
(Section 8.5), Destination Up (Section 8.9), Destination Update
(Section 8.13) and Link Characteristics Response (Section 8.16)
messages to indicate the amount of resources for transmission (with 0
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meaning ’no resources available’, and 100 meaning ’all resources
available’) at the destination. The list of resources that might be
considered is beyond the scope of this document, and is left to
implementations to decide.
The Resources (Transmit) data item contains the following fields:
0
1
2
3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Data Item Type
| Length
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
REST
|
+-+-+-+-+-+-+-+-+
Data Item Type:
Length:
TBD
1
Resources (Transmit): An 8-bit integer percentage, 0-100,
representing the amount of resources allocated to transmitting
data. Any value greater than 100 MUST be considered as invalid.
If a device cannot calculate REST, this data item SHOULD NOT be
issued.
9.19.
Relative Link Quality (Receive)
The Relative Link Quality (Receive) (RLQR) data item MAY appear in
the Session Initialization Response message (Section 8.4), Session
Update (Section 8.5), Destination Up (Section 8.9), Destination
Update (Section 8.13) and Link Characteristics Response
(Section 8.16) messages to indicate the quality of the link for
receiving data.
The Relative Link Quality (Receive) data item contains the following
fields:
0
1
2
3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Data Item Type
| Length
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
RLQR
|
+-+-+-+-+-+-+-+-+
Data Item Type:
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1
Relative Link Quality (Receive): A non-dimensional 8-bit integer,
0-100, representing relative link quality. A value of 100
represents a link of the highest quality. Any value greater than
100 MUST be considered as invalid.
If a device cannot calculate the RLQR, this data item SHOULD NOT be
issued.
9.20.
Relative Link Quality (Transmit)
The Relative Link Quality (Transmit) (RLQT) data item MAY appear in
the Session Initialization Response message (Section 8.4), Session
Update (Section 8.5), Destination Up (Section 8.9), Destination
Update (Section 8.13) and Link Characteristics Response
(Section 8.16) messages to indicate the quality of the link for
transmitting data.
The Relative Link Quality (Transmit) data item contains the following
fields:
0
1
2
3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Data Item Type
| Length
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
RLQT
|
+-+-+-+-+-+-+-+-+
Data Item Type:
Length:
TBD
1
Relative Link Quality (Transmit): A non-dimensional 8-bit integer,
0-100, representing relative link quality. A value of 100
represents a link of the highest quality. Any value greater than
100 MUST be considered as invalid.
If a device cannot calculate the RLQT, this data item SHOULD NOT be
issued.
9.21.
Link Characteristics Response Timer
The Link Characteristics Response Timer data item MAY appear in the
Link Characteristics Request message (Section 8.15) to indicate the
desired number of seconds the sender will wait for a response to the
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request. If this data item is omitted, implementations supporting
the Link Characteristics Request SHOULD choose a default value.
The Link Characteristics Response Timer data item contains the
following fields:
0
1
2
3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Data Item Type
| Length
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Interval
|
+-+-+-+-+-+-+-+-+
Data Item Type:
Length:
TBD
1
Interval: 0 = Do not use timeouts for this Link Characteristics
request. Non-zero = Interval, in seconds, to wait before
considering this Link Characteristics Request lost.
10.
Credit-Windowing
DLEP includes an optional Protocol Extension for a credit-windowing
scheme analogous to the one documented in [RFC5578]. In this scheme,
data plane traffic flowing between the router and modem is controlled
by the availability of credits. Credits are expressed as if two
unidirectional windows exist between the modem and router. This
document identifies these windows as the ’Modem Receive Window’
(MRW), and the ’Router Receive Window’ (RRW).
If the credit-windowing extension is used, credits MUST be granted by
the receiver on a given window - that is, on the ’Modem Receive
Window’ (MRW), the modem is responsible for granting credits to the
router, allowing it (the router) to send data plane traffic to the
modem. Likewise, the router is responsible for granting credits on
the RRW, which allows the modem to send data plane traffic to the
router.
Credits are managed on a destination-specific basis; that is,
separate credit counts are maintained for each destination requiring
the service. Credits do not apply to the DLEP session that exists
between routers and modems; they are applied only to the data plane
traffic.
Credits represent the number of octets, or an increment in the number
of octets, that MAY be sent on the given window. When sending data
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plane traffic to a credit-enabled peer, the sender MUST decriment the
appropriate window by the size of the data being sent. For example,
when sending data plane traffic via the modem, the router MUST
decriment the ’Modem Receive Window’ (MRW) for the corresponding
destination. When the number of available credits to the destination
reaches 0, a sender MUST stop sending data plane traffic to the
destination, until additional credits are supplied.
If a peer is able to support the optional credit-windowing extension
then it MUST include an Extensions Supported data item (Section 9.6)
including the value 1, from Table 4, in the appropriate Session
Initialization (Section 8.3) and Session Initialization Response
(Section 8.4) message.
10.1.
Credit-Windowing Messages
The credit-windowing extension introduces no additional DLEP signals
or messages. However, if a peer has advertised during session
initialization that it supports the credit-windowing extension then
the following DLEP messages MAY contain additional credit-windowing
data items:
10.1.1.
Destination Up Message
The Destination Up message MAY contain one of each of the following
data items:
o
Credit Grant (Section 10.2.1)
If the Destination Up message does not contain the Credit Grant data
item, credits MUST NOT be used for that destination.
10.1.2.
Destination Up Response Message
If the corresponding Destination Up message contained the Credit
Grant data item, the Destination Up Response message MUST contain one
of each of the following data items:
o
Credit Window Status (Section 10.2.2)
10.1.3.
Destination Update Message
If the corresponding Destination Up message contained the Credit
Grant data item, the Destination Update message MUST contain one of
each of the following data items:
o
Credit Window Status (Section 10.2.2)
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If the corresponding Destination Up message contained the Credit
Grant data item, the Destination Update message MAY contain one of
each of the following data items:
o
Credit Grant (Section 10.2.1)
o
Credit Request (Section 10.2.3)
10.2.
Credit-Windowing Data Items
The credit-windowing extension introduces 3 additional data items.
If a peer has advertised during session initialization that it
supports the credit-windowing extension then it MUST correctly
process the following data items:
+------------+------------------------------------------------------+
| Type Code | Description
|
+------------+------------------------------------------------------+
| 23
| Credit Grant (Section 10.2.1)
|
| 24
| Credit Window Status (Section 10.2.2)
|
| 25
| Credit Request (Section 10.2.3)
|
+------------+------------------------------------------------------+
10.2.1.
Credit Grant
The Credit Grant data item is sent from a DLEP participant to grant
an increment to credits on a window. The Credit Grant data item MAY
appear in the Destination Up (Section 8.9) and Destination Update
(Section 8.13) messages. The value in a Credit Grant data item
represents an increment to be added to any existing credits available
on the window. Upon successful receipt and processing of a Credit
Grant data item, the receiver MUST respond with a message containing
a Credit Window Status data item to report the updated aggregate
values for synchronization purposes, and if initializing a new credit
window, granting initial credits.
When DLEP peers desire to employ the credit-windowing extension, the
peer originating the Destination Up message MUST supply an initial,
non-zero value as the credit increment of the receive window it
controls (i.e., the Modem Recive Window, or Router Receive Window).
When receiving a Credit Grant data item on a Destination Up
(#msg_dest_up) message, the receiver MUST take one of the following
actions:
1.
Reject the use of credits for this destination, via the
Destination Up Response message containing a Status data item
(Section 9.1) with a status code of ’Request Denied’. (See
Table 3), or
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2.
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Initialize the appropriate window value of zero, then apply the
increment specified in the Credit Grant data item.
If the initialization completes successfully, the receiver MUST
respond to the Destination Up message with a Destination Up Response
message that contains a Credit Window Status data item, initializing
its receive window.
The Credit Grant data item contains the following fields:
0
1
2
3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Data Item Type
| Length
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
Credit Increment
:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
:
Credit Increment
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Data Item Type:
Length:
TBD
8
Reserved: A 64-bit unsigned integer representing the additional
credits to be assigned to the credit window.
Since credits can only be granted by the receiver on a window, the
applicable credit window (either the MRW or the RRW) is derived from
the sender of the grant. The Credit Increment MUST NOT cause the
window to overflow; if this condition occurs, implementations MUST
set the credit window to the maximum value contained in a 64-bit
quantity.
10.2.2.
Credit Window Status
If the credit-window extension is supported by the DLEP participants
(both the router and the modem), the Credit Window Status data item
MUST be sent by the participant receiving a Credit Grant for a given
destination.
The Credit Window Status data item contains the following fields:
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0
1
2
3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Data Item Type
| Length
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
Modem Receive Window Value
:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
:
Modem Receive Window Value
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|
Router Receive Window Value
:
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
:
Router Receive Window Value
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Data Item Type:
Length:
TBD
16
Modem Receive Window Value: A 64-bit unsigned integer, indicating
the current number of credits available on the Modem Receive
Window, for the destination referred to by the message.
Router Receive Window Value: A 64-bit unsigned integer, indicating
the current number of credits available on the Router Receive
Window, for the destination referred to by the message.
10.2.3.
Credit Request
The Credit Request data item MAY be sent from either DLEP
participant, via the Destination Update message (Section 8.13), to
indicate the desire for the partner to grant additional credits in
order for data transfer to proceed on the session. If the
corresponding Destination Up message (Section 8.9) for this session
did not contain a Credit Window Status data item, indicating that
credits are to be used on the session, then the Credit Request data
item MUST be silently dropped by the receiver.
The Credit Request data item contains the following fields:
0
1
2
3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Data Item Type
| Length
|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Data Item Type:
Length:
TBD
0
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11.
Dynamic Link Exchange Protocol (DLEP)
July 2015
Security Considerations
The potential security concerns when using DLEP are:
1.
DLEP peers may be ’spoofed’ by an attacker, either at DLEP
session initialization, or by injection of messages once a
session has been established, and/or
2.
DLEP data items could be altered by an attacker, causing the
receiving peer to inappropriately alter its information base
concerning network status.
The protocol itself does not contain any mechanisms for security
(e.g., authentication or encryption), as it assumes that an
appropriate level of authentication and non-repudiation is acheived
by use of [TLS] when necessary. This specification does not address
security of the data plane, as it (the data plane) is not affected,
and standard security procedures can be employed.
12.
IANA Considerations
This section specifies requests to IANA.
12.1.
Registrations
This specification defines:
o
A new repository for DLEP signals and messages, with sixteen (16)
values currently assigned.
o
Reservation of a Private Use numbering space for experimental DLEP
signals and messages.
o
A new repository for DLEP data items, with twenty-four (24) values
currently assigned.
o
Reservation of a Private Use numbering space in the data items
repository for experimental data items.
o
A new repository for DLEP status codes, with eight (8) currently
assigned.
o
Reservation of a Private Use numbering space in the status codes
repository for experimental status codes.
o
A new repository for DLEP extensions, with one (1) value currently
assigned.
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o
Reservation of a Private Use numbering space in the extension
repository for experimental extensions.
o
A request for allocation of a well-known port for DLEP TCP and UDP
communication.
o
A request for allocation of a multicast IP address for DLEP
discovery.
12.2.
Expert Review: Evaluation Guidelines
No additional guidelines for expert review are anticipated.
12.3.
Signal/Message Type Registration
A new repository must be created with the values of the DLEP signals
and messages.
All signal and message values are in the range [0..65535], defined in
Table 1.
12.4.
DLEP Data Item Registrations
A new repository for DLEP data items must be created.
All data item values are in the range [0..65535], defined in Table 2.
12.5.
DLEP Status Code Registrations
A new repository for DLEP status codes must be created.
All status codes are in the range [0..255], defined in Table 3.
12.6.
DLEP Extensions Registrations
A new repository for DLEP extensions must be created.
All extension values are in the range [0..65535].
allocations are:
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+-------------+-----------------------------------------------------+
| Code
| Description
|
+-------------+-----------------------------------------------------+
| 0
| Reserved
|
| 1
| Credit Windowing (Section 10)
|
| 2-65519
| Reserved for future extensions
|
| 65520-65534 | Private Use. Available for experiments
|
| 65535
| Reserved
|
+-------------+-----------------------------------------------------+
Table 4: DLEP Extension types
12.7.
DLEP Well-known Port
It is requested that IANA allocate a well-known port number for DLEP
communication.
12.8.
DLEP Multicast Address
It is requested that IANA allocate a multicast address for DLEP
discovery signals.
13.
Acknowledgements
We would like to acknowledge and thank the members of the DLEP design
team, who have provided invaluable insight. The members of the
design team are: Teco Boot, Bow-Nan Cheng, John Dowdell, and Henning
Rogge.
We would also like to acknowledge the influence and contributions of
Greg Harrison, Chris Olsen, Martin Duke, Subir Das, Jaewon Kang,
Vikram Kaul, Nelson Powell and Victoria Mercieca.
14.
References
14.1.
Normative References
[RFC2119]
14.2.
Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
Informative References
[RFC5246]
Dierks, T. and E. Rescorla, "The Transport Layer Security
(TLS) Protocol Version 1.2", RFC 5246, August 2008.
[RFC5578]
Berry, B., Ratliff, S., Paradise, E., Kaiser, T., and M.
Adams, "PPP over Ethernet (PPPoE) Extensions for Credit
Flow and Link Metrics", RFC 5578, February 2010.
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Appendix A.
Dynamic Link Exchange Protocol (DLEP)
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Discovery Signal Flows
Router
Modem
Signal Description
========================================================================
|
|
|-------Peer Discovery---->||
˜ ˜ ˜ ˜ ˜ ˜ ˜
Router discovery timer expires
without receiving Peer Offer.
|
|-------Peer Discovery---------->|
|
|
|
|
|
|<--------Peer Offer-------------|
:
:
:
:
Appendix B.
B.1.
Router initiates discovery, starts
a timer, send Peer Discovery
signal.
Router sends another Peer
Discovery signal.
Modem receives Peer Discovery
signal.
Modem sends Peer Offer with
Connection Point information.
Router MAY cancel discovery timer
and stop sending Peer Discovery
signals.
Peer Level Message Flows
Session Initialization
Router
Modem
Signal Description
========================================================================
|
|
|---------TCP connect---------->
|
|
|----Session Initialization----->|
|
|
|
|
|
|<--Session Initialization Resp.-|
|
|
|<<============================>>|
:
:
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Router connects to discovered or
pre-configured Modem Connection
Point.
Router sends Session Initialization
message.
Modem receives Session Initialization
message.
Modem sends Session Initialization
Response, with Success status data item.
Session established. Heartbeats
begin.
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B.2.
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Session Initialization - Refused
Router
Modem
Signal Description
========================================================================
|
|
|---------TCP connect---------->
|
|
|-----Session Initialization---->|
|
|
|
|
|
|
|
|<-Session Initialization Resp.--|
|
|
|
|
||---------TCP close------------||
B.3.
Router connects to discovered or
pre-configured Modem Connection
Point.
Router sends Session Initialization
message.
Modem receives Session Initialization
message, and will not support the
advertised extensions.
Modem sends Session Initialization
Response, with ’Request Denied’ status
data item.
Router receives negative Session
Initialization Response, closes
TCP connection.
Router Changes IP Addresses
Router
Modem
Signal Description
========================================================================
|
|-------Session Update---------->|
|
|
|
|
|<----Session Update Response----|
B.4.
Router sends Session Update message to
announce change of IP address
Modem receives Session Update message
and updates internal state.
Modem sends Session Update Response.
Modem Changes Session-wide Metrics
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Router
Modem
Signal Description
========================================================================
|
|
|<--------Session Update---------|
|
|
|
|
|----Session Update Response---->|
B.5.
Modem sends Session Update message to
announce change of modem-wide
metrics
Router receives Session Update message
and updates internal state.
Router sends Session Update Response.
Router Terminates Session
Router
Modem
Signal Description
========================================================================
|
|------Session Termination------>|
|
|
|-------TCP shutdown (send)---> |
|
|
|
|
|
|
|<---Session Termination Resp.---|
|
|
|
||---------TCP close------------||
B.6.
Router sends Session Termination
message with Status data item.
Router stops sending messages.
Modem receives Session Termination,
stops counting received heartbeats
and stops sending heartbeats.
Modem sends Session Termination Response
with Status ’Success’.
Modem stops sending messages.
Session terminated.
Modem Terminates Session
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Router
Modem
Signal Description
========================================================================
|
|<----Session Termination--------|
|
|
|
|
|
|
|
|
|---Session Termination Resp.--->|
|
|
|
||---------TCP close------------||
B.7.
Modem sends Session Termination
message with Status data item.
Modem stops sending messages.
Router receives Session Termination,
stops counting received heartbeats
and stops sending heartbeats.
Router sends Session Termination Response
with Status ’Success’.
Router stops sending messages.
Session terminated.
Session Heartbeats
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Router
Modem
Signal Description
========================================================================
|----------Heartbeat------------>|
|
|
|
Router sends heartbeat message
Modem resets heartbeats missed
counter.
˜ ˜ ˜ ˜ ˜ ˜ ˜
|---------[Any message]--------->|
|
|
|
|
When the Modem receives any message
from the Router.
Modem resets heartbeats missed
counter.
˜ ˜ ˜ ˜ ˜ ˜ ˜
|<---------Heartbeat-------------|
|
|
|
Modem sends heartbeat message
Router resets heartbeats missed
counter.
˜ ˜ ˜ ˜ ˜ ˜ ˜
|<--------[Any message]----------|
|
|
|
|
B.8.
When the Router receives any
message from the Modem.
Modem resets heartbeats missed
counter.
Router Detects a Heartbeat timeout
Router
Modem
Signal Description
========================================================================
||<----------------------|
|
||<----------------------|
|
|
|------Session Termination------>|
|
|
:
:
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Router misses a heartbeat
Router misses too many heartbeats
Router sends Session Termination
message with ’Timeout’ Status
data item.
Termination proceeds as above.
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B.9.
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Modem Detects a Heartbeat timeout
Router
Modem
Signal Description
========================================================================
|---------------------->||
Modem misses a heartbeat
|---------------------->||
Modem misses too many heartbeats
|
|
|
|<-----Session Termination-------|
|
|
:
:
Appendix C.
C.1.
Modem sends Session Termination
message with ’Timeout’ Status
data item.
Termination proceeds as above.
Destination Specific Signal Flows
Common Destination Signaling
Router
Modem
Signal Description
========================================================================
|
|
|<-------Destination Up----------|
|
|------Destination Up Resp.----->|
Modem detects a new logical
destination is reachable, and
sends Destination Up message.
Router sends Destination Up Response.
˜ ˜ ˜ ˜ ˜ ˜ ˜
|
|
|<-------Destination Update------|
Modem detects change in logical
destination metrics, and sends
Destination Update message.
˜ ˜ ˜ ˜ ˜ ˜ ˜
|
|
|<-------Destination Update------|
Modem detects change in logical
destination metrics, and sends
Destination Update message.
˜ ˜ ˜ ˜ ˜ ˜ ˜
|
|
|<-------Destination Down--------|
|
|
|
|------Destination Down Resp.--->|
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Modem detects logical destination
is no longer reachable, and sends
Destination Down message.
Router receives Destination Down,
updates internal state, and sends
Destination Down Response message.
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C.2.
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Multicast Destination Signaling
Router
Modem
Signal Description
========================================================================
|
|
|--------Destination Up--------->|
|
|
|
|<-----Destination Up Resp.------|
Router detects a new multicast
destination is in use, and sends
Destination Up message.
Modem updates internal state to
monitor multicast destination, and
sends Destination Up Response.
˜ ˜ ˜ ˜ ˜ ˜ ˜
|
|
|<-------Destination Update------|
Modem detects change in multicast
destination metrics, and sends
Destination Update message.
˜ ˜ ˜ ˜ ˜ ˜ ˜
|
|
|<-------Destination Update------|
˜ ˜ ˜ ˜ ˜ ˜ ˜
|
|
|--------Destination Down------->|
|
|
|
|<-----Destination Down Resp.----|
C.3.
Modem detects change in multicast
destination metrics, and sends
Destination Update message.
Router detects multicast
destination is no longer in use,
and sends Destination Down message.
Modem receives Destination Down,
updates internal state, and sends
Destination Down Response message.
Link Characteristics Request
Ratliff, et al.
Expires January 7, 2016
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Internet-Draft
Dynamic Link Exchange Protocol (DLEP)
July 2015
Router
Modem
Signal Description
========================================================================
Destination has already been
announced by either peer.
˜ ˜ ˜ ˜ ˜ ˜ ˜
|
|
|
|--Link Characteristics Request->|
|
|
|
|
|
|<---Link Characteristics Resp.--|
Router requires different
Characteristics for the
destination, and sends Link
Characteristics Request message.
Modem attempts to adjust link
status to meet the received
request, and sends a Link
Characteristics Response
message with the new values.
Authors’ Addresses
Stan Ratliff
VT iDirect
13861 Sunrise Valley Drive, Suite 300
Herndon, VA 20171
USA
Email: [email protected]
Bo Berry
Shawn Jury
Cisco Systems
170 West Tasman Drive
San Jose, CA 95134
USA
Email: [email protected]
Darryl Satterwhite
Broadcom
Email: [email protected]
Ratliff, et al.
Expires January 7, 2016
[Page 65]
Internet-Draft
Dynamic Link Exchange Protocol (DLEP)
July 2015
Rick Taylor
Airbus Defence & Space
Quadrant House
Celtic Springs
Coedkernew
Newport NP10 8FZ
UK
Email: [email protected]
Ratliff, et al.
Expires January 7, 2016
[Page 66]