Download Report

Converging Telco and Internet
Standards
Peter Darling
Manager, International & NGN,
Australian Communications Industry Forum
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Things Change!
• Ten years ago
 The Public Switched Telephone Network (PSTN)
was just completing the transition to digital
 The Internet was starting to move from academia
• Three years ago
 Dot.com mania ruled
 It was “reliably” forecast that the Internet was about
to take over as the sole communications medium
• Today
 There is a strike of capital, but
 convergence is becoming a reality
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In the Future
• Telephony and multi-media may be just another
application over the Internet, but
• There will need to be changes to support user
requirements, based current expectations.
• To make this happen, there needs to be
 Substantial resource investment, and
 Substantial standards work
• Much current telco standards work directly
relates to NGN (next generation networks)
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Network Generations
Fixed Network
Analogue PSTN
Mobile
Analogue Mobile
Data
X.25 Packet
(AMPS, NMT)
Digital PSTN
Digital Mobile (GSM, Frame Relay
CDMAOne)
“Carrier Grade IP”
3G
Internet
“Carrier Grade IP”
(CDMA2000, UMTS)
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PSTN
2G Mobile
• The PSTN/ISDN is based on 64 kbit/s digital
connections, with a separate “common channel”
signalling system
• Access may be analogue (telephony), 64 kbit/s digital (ISDN)
or low speed digital (mobiles)
• The network establishes an end-to-end digital connection for
the duration of each call
• The PSTN/ISDN is designed for high reliability,
specified at the national level and connecting to form
a global network,
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• The (public) Internet is based on the set of protocols defined by
the Internet Engineering Task Force (IETF)
• The primary protocol is the Internet Protocol (IP) which
describes a simple connectionless packet protocol able to
operate over a range of media
• Other protocols work in association with the IP, for example,
TCP to assist reliable end-to-end operation
• The Internet is defined by the Internet protocols rather than by a
standardised architecture
• The Internet provides open interfaces, supporting rapid innovation
ISP
“The Internet”
(best-endeavours
network)
ISP
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Telco Networks
• 64 kbit/s circuit switching
• Well defined architecture,
fixed and mobile.
• Designed for high reliability
and QoS
• Specified at national level
growing to global
• Main area for national
regulation
Dumb terminal, smart network
Current Internet
• Packet switching over
diverse media
• Defined by protocols rather
than architecture (TCP/IP)
• Specified at global level
• Best endeavours network –
no QoS guarantee
• Open interfaces support
rapid innovation
Smart terminal, dumb network
Next Generation Networks

Largely Packet based (IP & ATM), with necessary extensions to give

a level of service equal to or better than current carrier networks
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Network Evolution
• There are different paths (not mutually
exclusive) by which “an NGN” could evolve:
 Interconnection of enterprise IP VPNs
 IP expansion of existing carrier networks
 New IP-based networks providing integrated
service
 Addition of QoS support to the existing public
Internet
• What is the underlying demand, the business
case and the likely timing? (The economics of
adding QoS to the existing Internet do not
seem compelling.)
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Quality of Service Provision
• Future networks need to provide adequate Quality of
Service to support real-time interactive services (e.g.
voice)
• There has been extensive work on “adding” QoS to the
Internet
• Implementation of QoS can be
 standards driven (primarily IETF work),
 based on proprietary approaches
 provided by traffic segregation and traffic engineering (overprovision of underlying resources)
• Almost all work in the IETF has been directed with a
single network rather than across networks (NNI or
inter-domain)
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Carrier Networks are not homogeneous
• Carrier networks consist of multiple domains
Domain 3
Service network
Service
Domain
Client
Transport Network
Domain 1
Transport Network
Domain 2
• each domain may have its own policies
• each domain may have its own commercial goals
• and possibly its own protocols & transport
Source: ITU-T SG 11
Client
Relevant
interfaces
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Why Change?
The current circuit switched PSTN provides
good service. What are the likely drivers for
change to a packet-based network?
• Flexibility
 The PSTN is based on carrying 64 kbit/s circuits.
• Services at bit-rates below this can be carried (but not
efficiently)
• Services at bit-rates above this can only be carried by
combining 64 kbit/s circuits
 Open interfaces supporting innovation
• Economics
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PSTN
ISP
2G Mobile
“Carrier Grade”
IP-based
Networks
ISP
“The Internet”
(best-endeavours
network)
ISP
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What is Needed for “Carrier Grade IP”?
• The current Internet
 Does not provide differentiated quality connections
 Queues packets at peak times for maximum
efficiency
• If the Internet is not congested, real-time (e.g.
voice) packets can be delivered, but if there is
congestion, real-time services cannot be
supported reliably.
• There is a need for connection-oriented
support to provide a required level of QoS for
the duration of a connection (or, in telco
terms, a call)
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To provide QoS…..
Backbone transport
• An underlying backbone transport is required (for example, by
SONET/SDH over optical fibre or radio)
• Backbone resource control protocols such as GMPLS with
RSVP-TE or CR-LDP can be used to provide support for
resource allocation
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To provide QoS…..
Bearer Control
Backbone transport
• It is then necessary to establish specific support for end-to-end
connections for the duration of the connection/call.
• This can be provided by MPLS enabled routers, or by the use of
the virtual circuit capabilities of ATM
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To provide QoS…..
Call Control
Bearer Control
Backbone transport
• Per call (or session) call control is needed for the duration of
each call, to set up, supervise and clear-down.
• Possible protocols include
 BICC (from the ITU-T)
 SIP (from the IETF)
 H.323 (from the ITU)
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To provide QoS…..
Service/application
Call Control
Bearer Control
Backbone transport
• SIP and H.323 are end-to-end protocols
• An alternative approach is to use centralised control from a
Media Gateway Controller / Softswitch, combining bearer and
call control
 Megaco/MGCP H.248 has been developed by IETF and ITU
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QoS Support
Translation of
Service Request
to QoS/Flow RQ
Translation of
QoS/Flow RQ to
Service Request
Signalling Message (with
QoS/Flow RQ message)
• Caller must specify requirements
• Access network and subsequent networks must provide the
required QoS for the duration of the call
Current Internet protocols can support this within one network,
but not across different networks
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PSTN
ISP
“Carrier Grade”
IP-based
Networks
2G Mobile
ISP
?
?
ISP
“The Internet”
(best-endeavours
network)
ISP
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End-to-End Connectivity?
There is no shortage of possible approaches – and they are all
in use!
The problem
 How to guarantee end-to-end service with the required QoS across
multiple networks using incompatible implementations
[the subject of current international work]
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Today’s Network Architectures
Frame
Relay
Networks
IWF
PSTN/ISDN
IWF
IP/MPLS
Networks
IWF
IWF
IWF
Radio
Access
Networks
IWF
IWF
IWF
IWF
Ethernet
Networks
Wireless
Access
ATM
Networks
Source: ITU-T SG 13
•
•
•
•
Multiple, interworked, interdependent networks
Diversity of control and management architectures
Capacity and performance bottlenecks
Each network has its own control plane and management plane
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Near Term Evolution
PSTN/ISDN
Q & X series Rec.
Rec. Q.931
IWF
PSTN/ISDN
Frame
Relay
Networks
Rec. I.580
Rec. Q.2931, PNNI
IWF
IWF
Rec. I.555
Rec. I.580
PSTN/ISDN
OSF & NM, M
series Rec.
ATM
Networks
IETF RFCs
IWF
Wireless
access
FR OSF & NM
IWF
IP-based
Networks
Rec. Y.1310
ATM OSF & NM, M series Rec.
SNMP based
For
• Convergence on ATM core
networking enables initial stage of
unified management and control
• Enhanced performance and QoS
capabilities for multi-services over
common platform
Against
• Lack of service transparency
between IP based services
and ATM/PSTN services
OSF = Operating Support Function
Source: ITU-T SG 13
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Medium-term - Convergence on MPLS Core
ATM
Networks
IWF
Frame
Relay
Networks
Frame
Relay
Networks
MPLS NETWORK
IWF
IWF
IWF
Ethernet
Networks
IWF
Ethernet
Networks
IWF
ATM
Networks
Label Switching Router (LSR)
Label Switched Path (LSP)
• Requires well defined interworking mechanism for all services
• Transfer plane functions
• Control plane functions
• Management plane functions
Source: ITU-T SG 13
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Inter-Network Resources
• Successful solutions have to combine
 End to end operation control
 Inter-domain resource negotiation
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Inter-network Negotiation
Alternative approaches include
 Requiring each network to support a limited range of QoS/network
services (inflexible and prescriptive)
 Network by network negotiation (but how to ensure required service
is available?)
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Ongoing Work
• International and national work is need to
introduce interoperable next generation
networks. Areas requiring work include






Architecture and Protocols
End to end QoS
Service platforms
Network management
Lawful interception
Security
• This work is being carried out in the IETF, the
ITU and regional telco standards bodies such
as ETSI
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Ongoing Work
• Given the proposed use of Internet Protocols,
much current IETF work is directly relevant
• Work is needed to define inter-network (interdomain) interconnection and operation
• The following slides summarise some of the
current work at the international level. Other
bodies working on NGN include fora and
consortia such as the Multi-service Switching
Forum and the MPLS Forum.
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International Work - IETF
• RTP (Real Time Protocol)
 Carries VoIP audio media
 Used by H.323, SIP, Megaco/H.248, others.
• SDP (Session Description Protocol)
 Describes multimedia sessions
 Used widely as well, see above.
• SIP (Session Initiation Protocol)
 Rendezvous protocol, discovery and session
management
 Commonly used as VoIP signalling protocol
 Associated with MMUSIC, SIP, SIPPING, SIMPLE
WGs
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International Work - IETF
• ENUM (E.164 Number Mapping)
 Transforms E.164 telephone numbers into URLs
 used for SIP, HTTP, SMTP, etc.
 Interim operation plan for e164.arpa is a collaboration
between IETF (Internet Architecture Board) and ITU-T
(Study Group-2)
• SIP-T (Interworking SIP & ISUP)
 Defines encapsulation of ISUP in SIP and mapping between
SIP & ISUP fields
 SIP-T architecture is approved document
 SIP-ISUP mapping is close to approval
 Current ITU-T SG 11 work on application for NGN-legacy
network interworking
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International Work - IETF
• Interworking SIP & H.323
 Requirements almost complete
• Security and VoIP
 TLS, Digest, S/MIME, IPSEC IETF protocols from
Security Area
 Used to secure SIP and SDP
 SRTP
 SIP Privacy/Identity work
 MIDCOM (firewall control)
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International Work - IETF
• Media Gateway Control
 Megaco
 MGCP
• Transports for VoIP
 SCTP
• Signalling transport
 New work begun on DCCP, unreliable protocol
with congestion control properties
• Service development
 CPL (Call Processing Language)
 SIP CGI (Applying HTTP service creation to SIP)
 New work underway on Speech Services Control
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International Work - IETF
• Accounting and Management
 DIAMETER
• AAA protocol
• Signalling Compression
 Robust Header Compression
• Specifications for IP/UDP/RTP headers and the SIP/SDP
messages to be compressed, especially for wireless
VoIP uses.
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International Work - ITU
• ITU-T Study Group 13
 Overall responsibility for IP work
 Recommendations/areas of work include
• Rec. Y.1541: Quantifying User QoS Needs in IP Terms
• Rec. Y.1221: Traffic and Congestion Control in IP Based
Networks
 Leading ITU’s “NGN 2004” project
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International Work - ITU
• ITU-T Study Group 11
 Responsible for signalling and interworking. Current work
includes
•
•
•
•
•
Interactions between IN and IP-based networks
IP-related signalling protocols
Bearer (ATM, IP) Independent Call Control (BICC)
Signalling transport over IP
Use of SIP for user access and network-to-network interfacing
 Has just initiated new projects on signalling control
• between session control functions (across networks),
• between session, resource and bearer control, and
• between session control and user profile management.
 Other new work on control architecture and signalling
requirements about to commence.
34
International Work - ITU
• ITU-T Study Group 12
 Lead group for end-to-end transmission
performance. Areas of work include
•
•
•
•
•
•
•
•
•
Transm. Req’ts for IP gateways and terminals
E-Model (model for speech quality incl.VoIP)
Transm. Plan. for VB, Data and Multimedia
Transm. of multiple interconnected networks
Voiceband services via IP networks
Multimedia QOS and perf. requirements
Effects of multiple IP domains on VoIP
QOS coordination in the ITU (as Lead SG)
In-service non-intrusive assessment of VoIP
35
International Work - ITU
• ITU-T Study Group 16
 Lead group for multimedia and convergence. Work
includes
• Voice Coding
• Video Coding
• Multimedia Signalling; including Data Conferencing,
Modems, Facsimile, Call control and conference control
and Media gateway control (H.248)
• Security
• Multimedia Architecture (H.323)
• Mobility
• Emergency Telecommunication Services
36
International Work - ETSI
• Considerable NGN work in all areas,
including
 TIPHON (VoIP and Multimedia)
 SPAN (Signalling and interworking)
 Security and Coding work
• Co-ordinated by ETSI Board “NGN
Implementation Group”
• Major input to 3GPP IP work
37
ACIF NGN Project
• ACIF’s Strategic Plan in early 2001 identified need to
work on “Next Generation Networks”
• Meetings with ACA, ACCC and SPAN confirmed they
had a similar interest.
• ACCC sponsored an initial consultancy in second
half of 2001 “to raise issues”
• ACIF held an NGN seminar in May 2002 to scope
the issues
• Attendees proposed a continuing industry
“conversation” on NGN matters.
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ACIF NGN Project
• The ACIF Board agreed to support an ACIF NGN
Project, working through the ACIF NGN Framework
Options Group (“NGN FOG”).
• The aim of the ACIF NGN Project is to help all
involved discuss issues that cross current
boundaries, including
 Internet/telco divisions
 Regulatory issues (ACA and ACCC)
 Industry issues (including self-regulation
requirements)
 Policy issues
• An early agreement was that user requirements
must be the main driver of this work.
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NGN FOG Work
• The main task of the NGN FOG is to assist
understanding of the transition to next
generation network equipment. The NGN
FOG work involves consideration of issues
including





Technical standards
End-user issues
End-to-end services
Interconnection across networks
Regulatory issues (both self-regulation and
government regulation
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You are invited….
……to help with this work
Details at
www.acif.org.au/ngn
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