System information

422 Features

The IP acquisition is unsuccessful if either the server or the client decides

not to participate, as follows:

•

If the DHCP server cannot supply the requested information, it sends a

DHCPNAK message and no IP address is assigned to the client. This

can happen if the requested IP address has already been assigned

to a different client. See Figure 78 "IP acquisition sequence: Case 2"

(page 422).

• If the client decides to reject the final offer (after the server sends a

DHCPACK message), the client sends a DHCPDECLINE message

to the server, telling the server the offer is rejected. The client must

restart the IP acquisition by sending another DHCPDISCOVER

message in search of another offer.

Figure 78

IP acquisition sequence: Case 2

Case 3

Finally, when a client is finished with a particular IP address, it sends a

DHCPRELEASE message to the server which reclaims the IP address. If

the client requires the same IP address again, it can initiate the process as

follows:

1. The IP Phone broadcasts a DHCPREQUEST to a particular DHCP

server by including the server’s IP address in the Server IP Address

field of the message. Since it knows the IP address it wants, it

requests it in the DHCP message.

2. The DHCP server sends a DHCPACK message if all the parameters

requested are met.

Nortel Communication Server 1000

IP Phones Fundamentals

NN43001-368 05.02 26 May 2009