User's Manual

Network features 443
For the IP Phone to accept Offers/Acks, the messages must contain all
of the following:
•
A router option (needs a default router to function)
•
A subnet mask option
• A Vendor Specific option as specified below or a Site Specific option
as specified below.
—
The initial DHCP implementation required only the Vendor Specific
encapsulated sub-option. In inter-op testing with Windows NT (up
to Service Release 4), it was discovered that Windows NT does
not properly adhere to RFC 1541. As a result this option is not
possible. The implementation was changed to add support for
either Vendor Specific sub-ops or Site Specific options. This new
extension has been tested and verified to work with Windows NT.
— The site-specific options are all DHCP options between 128 (0x80)
and 254 (0xFE). These options are reserved for site specific use
by the DHCP RFCs.
Format for IP Phone DHCP Class Identifier Field
All IP Phones fill in the Class ID field of the DHCP Discovery and Request
messages with the following:
"Nortel-i2004-A", where:
•
ASCII encoded, NULL (0x00) terminated
•
unique to IP Phone 2004
•
"-A" uniquely identifies this version
Format for IP Phone DHCP Encapsulated Vendor Specific Field
This sub-option must be encapsulated in a DHCP Vendor Specific Option
(refer to RFC 1541 and RFC 1533) and returned by the DHCP server as
part of each DHCP OFFER and ACK message in order for the IP Phone
to accept these messages as valid.
The IP Phone parses this option’s data and uses it to configure the
information required to connect to the TPS. The sub-option must be
present, or a similarly encoded site-specific option must be sent. See
“Format of the Encapsulated Vendor Specific Sub-option field” (page 444) .
Configure the DHCP server to send one or the other – not both.
Nortel Communication Server 1000
IP Phones Fundamentals
NN43001-368 05.06 30 April 2010
Copyright © 2003-2010 Nortel Networks. All Rights Reserved.
.