Avaya 1110 Fundamentals page 377

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.
Important:
Phase 0 and Phase I IP Phones cannot accept a DHCPOFFER that contains a list of
OPTIONS larger than 312 bytes. If the total size of the DHCP OPTIONS is larger than 312
bytes the Phase 0 and Phase I 1 IP Phones do not successfully boot and register to the
TPS.
Important:
In an environment that combines IP Phones that support the Nortel-i2004-B option with the
Phase 0 IP Phone 2004, Phase 1 IP Phone 2002, or Phase 1 IP Phone 2004, you must
ensure one of the following:
• the Nortel-i2004-B option string does not exceed 590 bytes
• the Phase 0 or Phase 1 IP Phones are serviced with a DHCPOFFER that excludes the
Nortel-i2004-B option
Format for IP Deskphone DHCP Class Identifier option
All IP Deskphones fill in the Class ID option of the DHCPDISCOVER and DHCPREQUEST
messages with the null-terminated, ASCII-encoded string Nortel-i2004-A or Nortel-i-2004-B,
where A or B identifies the version number of the information format of the IP Phone.
The Class Identifier Nortel-i2004-A and Nortel-i-2004-B must be unique in the DHCP server
domain.
The following definition describes the model-specific, encapsulated IP Deskphone Vendor
Specific Option for the Nortel-i2004-A string. For information about the Nortel-i2004-B string,
see Automatic provisioning using DHCP
DHCP vendor-specific option (refer to RFC 1533) and returned by the DHCP server as part of
each DHCPOFFER and DHCPACK message for the IP Deskphone to accept these messages
as valid. The IP Deskphone extracts the relevant information from this option and uses it to
configure the Connect Server IP address, the port number (4100), a command value (1), and
the retry count for the primary and secondary Connect Servers.
Either this encapsulated Vendor Specific Option or a similarly encoded site-specific option must
be sent. The DHCP server must be configured to send one or the other, but not both. The
choice of using the vendor-specific or the site-specific option is provided to enable Windows
NT DHCP servers to support the IP Deskphone. Windows NT servers do not properly
implement the Vendor Specific Option, and as a result, Windows NT implementations must
use the Site Specific version.
The format of the encapsulated Vendor Specific option is Type, Length, and Data, described
in the following sections.
Type (1 octet):
There are five types:
• 0x80 (Site Specific option 128)
• 0x90 (Site Specific option 144)
IP Deskphones Fundamentals
on page 463. This option must be encapsulated in a
Network features
February 2013 377