Avaya 1110 Fundamentals page 387

7. If the IPs match and there is no problem supplying the requested information, the
8. If the final offer is not rejected, the IP acquisition sequence is complete.
Case 2
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
sequence: Case 2
• 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 70: 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
2. The DHCP server sends a DHCPACK message if all the parameters requested are
Case 3 is similar to Case 1, except the first two messages have been eliminated. This reduces
the amount of traffic produced on the network. See
3 on page 388.
IP Deskphones Fundamentals
DHCP server assigns the IP address to the client by sending a DHCPACK.
on page 387.
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.
met.
Figure 70: IP acquisition
Figure 71: IP acquisition sequence: Case
Network features
February 2013 387