Configuring DHCP options on non-NetWare 5 DHCP servers

(Last modified: 31Jan2003)

This document (10054413) is provided subject to the disclaimer at the end of this document.

goal

fact

DHCP

3rd party DHCP server

Novell NetWare 5.1

Novell NetWare 5.0

Formerly TID: 2953404

fix

For additional information on configuring Novell-specific options in the Microsoft Windows 2000 DHCP service, see </a href="http://support.microsoft.com/support/kb/articles/Q285/0/19.ASP">Microsoft Knowledgebase article Q285019</a>.

Novell does not support or assist with exactly how to implement DHCP option configurations on non-NetWare DHCP servers. This document is provided only as reference for advanced users. To deliver the options discussed here to Novell Windows-based clients, the DHCP server must support and respond to DHCP INFORM request packets. (Currently it is known that the Microsoft Windows NT 4.0 DHCP server does not support DHCP INFORM requests or responses.) The DHCP options discussed in this document are 78, 79, 63-12, 63-13, 63-14. For additional information please see the document How to configure DHCP to hand out SLP/CMD information.

Option 78 - SLP Directory Agent
Option 79 - SLP Scope
Option 63-12 - CMD Network number
Option 63-13 - CMD server resolution stale time
Option 63-14 - IP addresses of Migration agents.

These options are easily configured on a NetWare 5.x DHCP server using the DNS/DHCP administration tool. The NetWare 5.x DHCP server was designed to support these options. However, other DHCP servers from third-party vendors may not fully support these options. If the DHCP server does support the manual configuration of options 78, 79, and 63 (i.e. allows to the manual entry of binary data to be returned for a manually defined option value) you can configure that DHCP server to hand out these options to NetWare 5 clients.

To do this you would configure each of these 3 options with raw hex data values that would be sent to the client and represents the configuration parameters you desire. The sections below describe how to accomplish this for each particular option.

CMD configuration option 63 (3F hex)-

For example you would like to send a CMD network number of fffffffd, a server resolution stale time of 15, and a migration agent address of 15.0.0.5 you would configure option 63 with the following hex data.

12 02 00 0c 04 ff ff ff fd 0d 02 00 0f 0e 04 0f 00 00 05

Explanation of data

12 - total length of option data in hex*(see footnote).
02 00 - Flag information that must always be present.
0c - Begin sub option 12.
04 - Length of sub option 12.
ff ff ff fd - IPX network number in hex.
0d - Begin sub option 13.
02 - Length of sub option 13.
00 0f - IPX time in minutes configured in hex.
0e - Begin sub option 14.
04 - Length of sub option 14.
0f 00 00 05 - IP address of migration agent in hex.
(If you need to configure more that one migration agent increase the length of sub option 14 and add the other IP addresses one after another. For example 2 MA's would have a length of 08 and IP address section would be xx xx xx xx xx xx xx xx).

SLP Directory Agent.

This is option 78 (4E hex). As an example we will configure 1 DA address of 16.0.0.4. You would configure option 78 with the following hex data*.

06 80 04 10 00 00 04

Explanation of data.

06 - total length of option 78*(see footnote).
80 - Flags that need to be set.
04 - Length of the DA address.
10 00 00 04 - DA IP address in hex.

MULTIPLE SLPDAs:
Option 78 (4E hex)
**Same footnote as above, if your server autocalculates the length, then omit it from the Hex data

(09) 01 xx xx xx xx yy yy yy yy

Explanation of data.

09 - total length of option 78**
01 - Flags that need to be set.
xx xx xx xx - first DA address.
yy yy yy yy - second DA address.

SLP Service Scope option 79 (4F hex).

It is not always required to pass a scope to a client. Once the client contacts a DA it will determine what scopes that DA supports and then query that DA for its SLP information. To configure this option you need to enter the scope name in ASCII hex. As an example we will pass the scope name "scope1" to the client. You would enter the following hex data into option 79.

08 00 03 73 63 6f 70 65 31

Explanation of data.

08 - Total length of option 79*(see footnote).
00 03 - Character encoding information.
73 63 6F 70 65 31 - "scope1" in ASCII hex.

Below is a portion of a LAN trace that was taken when a client was given the information described in the above examples. This is what you should see when looking at a LAN trace of when the DHCP server sends a DHCPACK in response to the clients request for option data in the DHCPINFORM packet.

0110: 00 00 00 00 00 00 63 82 53 63 35 01 05 36 04 0f
0120: 00 00 06 01 04 ff 00 00 00 03 04 0f 00 00 02 06
0130: 04 0f 00 00 05 0f 0b 6e 6f 76 65 6c 6c 2e 63 6f
0140: 6d 00 3f 12 02 00 0c 04 ff ff ff fd 0d 02 00 0f
0150: 0e 04 0f 00 00 05 4e 06 80 04 10 00 00 04 4f 08
0160: 00 03 73 63 6f 70 65 31 55 04 10 00 00 04 ff 00.

*Notes for Windows 2000 DHCP server administrators:

Windows 2000 DHCP servers have been observed to automatically calculate the total length of the option data being defined when using manual entry of a "Binary" option type. This total length is sent as the first byte of the option data, ahead of the manually entered data bytes themselves.

When manually defining the data for options on the Windows 2000 DHCP server, it may be necessary to leave out the length value in the data being entered, to account for the Windows 2000 DHCP server automatically pre-pending the length value for whatever manual data is entered.

If you don't leave the length value out of the manually entered data, the resulting packet sent to the client will actually have two length field bytes (one manually entered and one generated by the DHCP server) and the option will not be correctly received or interpreted by the clients.

Note also that Microsoft's DHCP server service and administration tools (as observed on Windows 2000 Server SP2) did not permit defining option 63 (CMD configuration) through the administration interface, declaring that option 63 fell within a reserved range of options (yet the DHCP server doesn't already have a definition for option 63).

One unsupported method by which it was found the option 63 definition could be added was by manually creating the definition in the registry. The following example .REG file created option 63 as a Binary-type option which could then be selected in any of the DHCP option delivery lists. Note that this is an unsupported approach, and future Windows 2000 DHCP server services may change the data required to successfully create the 63 option definition. Use at your own risk:

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\DhcpServer\Configuration\OptionInfo\063]
"OptionName"="CMD Configuration"
"OptionComment"="Novell CMD protocol configuration"
"OptionClassName"=""
"OptionVendorName"=""
"OptionType"=dword:00000000
"OptionId"=dword:0000003f
"OptionValue"=hex:18,00,00,00,06,00,00,00,01,00,00,00,00,00,00,00,01,00,00,00,\
00,00,00,00

document

Document Title:	Configuring DHCP options on non-NetWare 5 DHCP servers
Document ID:	10054413
Solution ID:	NOVL16380
Creation Date:	21Jun2000
Modified Date:	31Jan2003
Novell Product Class:	Connectivity Products NetWare

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