User's Manual

Chapter 7: Configure the DHCP Server
The DHCP server requires special configuration in Full DHCP mode. The IP Deskphone with SIP Software
obtains Device Settings parameters from specially-configured DHCP servers.
The IP Deskphone with SIP Software requests the following Device Settings parameters from the DHCP
server:
• IP address configuration for the IP Deskphone
• subnet mask for the IP Deskphone IP address
• default gateway for the IP Deskphone subnet
• DNS server
• Provisioning Server
It is also possible to obtain the DNS IP automatically without any special configuration of the DHCP server.
This means that there is no need to configure the Avaya-specific Vendor Class Identifier (Option 60) on
the DHCP server. However, the provisioning server address needs to be manually defined within the
Device Settings menu.
Configure the DHCP server to support SIP IP Deskphone
class identifier
After the DHCP server is configured to recognize the IP Deskphone with SIP Software as a
unique IP Deskphone, the DHCP server can treat the IP Deskphone differently than other
DHCP Deskphones. An IP Deskphone-aware DHCP server can automatically configure IP
Deskphones by sending all information that the IP Deskphone requires.
The IP Deskphone and the DHCP server communicate using a unique class identifier. After
the IP Deskphone first sends the DHCP DISCOVER, it includes the Nortel-SIP-Phone-A ASCII
string within the Vendor Class Identifier (Option 60). The DHCP server recognizes this special
Vendor Class Identifier (Option 60) and sends back OFFER, which also includes the same
Vendor Class Identifier. This makes it possible to notify the IP Deskphone with SIP Software
that the server is IP Deskphone-aware, and that it is safe to accept the offer from the server.
Every IP Deskphone with SIP Software fills in the Vendor Class ID option of the
DHCPDISCOVER and DHCPREQUEST messages with the null-terminated, ASCII-encoded
string Nortel-SIP-Phone-A, where A identifies the version number of the information format of
the IP Deskphone.
The Class Identifier Nortel-SIP-Phone-A must be unique in the DHCP server domain.
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