Siemens
How to Configure DHCP Options for DLS
DHCP Options 43 and 60
Contents
How to Configure the DHCP Options for DLS...............................................................2
Document Scope......................................................................................................2
Vendor Class Identifiers............................................................................................2
Vendor Specific Information.....................................................................................2
OptiPoint Boot Process.............................................................................................2
Configuring the Vendor Class Identifiers..................................................................3
Configuring Vendor Specific Information..................................................................6
Vendor Specific Information for Vendor Class OptiPoint ..........................................6
Vendor Specific Information for Vendor Class OptiIpPhone......................................8
Assigning the Vendor Options to a DHCP Scope.......................................................9
Examining an Ethereal Trace of an OptiPoint Booting up.......................................10
First DHCP Discover............................................................................................10
First DHCP Offer .................................................................................................12
Second DHCP Discover.......................................................................................13
Second DHCP Offer.............................................................................................14
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Siemens
How to Configure DHCP Options for DLS
How to Configure the DHCP Options for DLS
Document Scope
This document covers how to configure the various Vendor Class Identifiers and
associated DHCP Options required for Siemens IP Phones and Deployment Server
running on voice VLANs. The screen shots in the documents were taken from a DHCP
Server running on Windows 2000 Server software. The document uses the DHCP
Console to configure the Options rather than the command line.
Please note there is a known bug in the DHCP console for Windows 2003 which was not
fixed with Service Pack 1. Option 43 Code 1 has to be created using the command line.
Vendor Class Identifiers
The Vendor Class Identifiers (VCI) are also called Option 60. They are used to identify
different vendor equipment. When a DHCP Discovery is made from a Siemens OptiPoint
phone is sends a Vendor Class Identifier to the DHCP server so that the server can assign
not only an IP address and subnet but also Vendor Specific Information (Option 43).
Siemens OptiPoint phones have two Vendor Class Identifiers (OptiPoint and OptiIpPhone).
Vendor Specific Information
Vendor Specific Information (VSI) can be sent to a device via the DHCP Offer. The DHCP
Server uses Option 43 to do this. In the case of the Siemens IP Phones this information
can contain; a VLAN tag and the Deployment Server IP Address. Different information is
identified within Option 43 by using Option 43 Codes (02 is VLAN tag, 03 is the DLS IP
Address). In order to ensure that the IP Phone only reads VSI meant for Siemens IP
Phones each Option 43 starts with a code 01 – Siemens (a tag identifying the information
as having come from a “trusted source”. If this tag is not included the phone will not
read the Option 43 information.
OptiPoint Boot Process
When an OptiPoint boots up it sends a DHCP Discovery and a VCI (OptiPoint) and
receives a DHCP Offer containing an IP address, a subnet mask and a VLAN ID (providing
these options have been set). The phone will then Release this IP Address and make a
second DHCP Discovery on the assigned VLAN using a new VCI of OptiIpPhone. The
DHCP will send out a new Offer which will contain the DLS IP address (if configured).
Please note that each Offer must also include code 01 (Siemens) in its Option 43. If this
is not the case the phone will not accept the Option 43 information. The phone will then
send out an ARP for the DLS and, assuming a response it will contact the DLS sending its
MAC address. If the DLS has been configured for Plug and Play it will then send all the
required information to the phone and the phone will then reboot and come up in a
working state.
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Siemens
How to Configure DHCP Options for DLS
Configuring the Vendor Class Identifiers
The following screen grabs show how to configure the Vendor Class Identifiers
(OptiPoint and OptiIpPhone). The information must be entered exactly as shown.
In the DHCP Console highlight the DHCP Server – Right Hand Mouse (RHM) and select
Define Vendor Classes. Add. Give the New class a Display Name and then IN the
ASCII type in OptiPoint (exactly as below)
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How to Configure DHCP Options for DLS
Repeat the same process for the next VCI (OptiIpPhone).
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Siemens
How to Configure DHCP Options for DLS
Configuring Vendor Specific Information
Once the Vendor Class Identifiers are created/configured you need to create the Vendor
Specific Information to be sent for each identifier.
Vendor Specific Information for Vendor Class OptiPoint
Highlight the DHCP Server – RHM – Set Predefined Options
Select the Option Class OptiPoint - Add
Give the Option a Name: Siemens Tag
Data Type: String
Code: 1
OK
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Add the string Siemens (exactly)
Siemens
How to Configure DHCP Options for DLS
Repeat for Code 2, the VLAN ID.
Against the OptiPoint class
Add a new option for VLANs
Name: VLAN Tag
Data Type: Binary
Code: 2
OK
Edit Array
Input the VLAN ID in Decimal using the New value
box and the Add button as shown. The final value
must have 4 bytes as shown below.
The final value must use 4 Bytes and the value is changed into Hex. If this input is not
correct the IP Phone will not be able to understand the VLAN instruction. The example
shows the VLAN ID 0 0 0 20 having been put into code 2 and shows it as 00 00 00 14.
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How to Configure DHCP Options for DLS
Vendor Specific Information for Vendor Class OptiIpPhone
Highlight the DHCP Server – RHM – Set Predefined Options
Select the Option Class OptiIpPhone Add
Add the string Siemens (exactly)
Give the Option a Name: Siemens Tag
Data Type: String
Code: 1
OK
Repeat for Code 3, the DLS IP Address.
Against the OptiIpPhone class Add a
new option for DLS IP Address
Type in the DLS at the string as shown
exactly as shown.
:18443
Name: DLS IP Address
Data Type: String
Code: 3
OK
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sdlp://160.140.030.200:18443
Note that each octet of the IP address
must contain 3 digits else the phone can
not contact the DLS correctly.
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Siemens
How to Configure DHCP Options for DLS
Assigning the Vendor Options to a DHCP Scope
Once the Vendor Options have been set they need to be assigned to every scope that
will use these options.
Scope Options – RHM – Configure
Options
Select the Vendor Class
Tick the relevant Options
OptiPoint – 001 and 002 - Apply
OptiIpPhone – 001 and 003 – Apply
OK
Once you have selected the options your Scope Options should like that below. With two
Options against both the Vendors (OptiPoint and OptiIpPhone)
:18443
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How to Configure DHCP Options for DLS
Examining an Ethereal Trace of an OptiPoint Booting up
The following screen shots show a trace of an OptiPoint phone booting up from Factory
Defaults. They show two DHCP Discover messages and two DHCP Offers. Each Discover
message shows the Vendor Class Identifier and each Offer shows the correct Option 43
data sent to the phone.
The trace uses VLAN ID 20 and a DLS address of 160.140.030.200. Please do not be put
off by the IP addresses, in this case the DHCP Server and the DLS server are the same
machine and so they have the same IP addresses.
First DHCP Discover
Vendor Class Identifier (option 60) – OptiPoint
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How to Configure DHCP Options for DLS
First DHCP Offer
Vendor Specific Information (Option 43)
Code 01 – Siemens
Code 02 – 00 00 00 14 (VLAN ID =20)
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Siemens
How to Configure DHCP Options for DLS
Second DHCP Discover
Vendor Class Identifier (Option 60) – OptiIpPhone
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Siemens
How to Configure DHCP Options for DLS
Second DHCP Offer
Vendor Specific Information (Option 43)
Code 01 – Siemens
Code 02 – sdlp://160.140.030.200:18443
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