User's Manual

UTT Technologies Chapter 7 Advanced Setup
http://www.uttglobal.com Page 154
DHCP server will reclaim the IP address if the lease expires, so the client has to renew
the lease in order to use the IP address longer. When one half of the lease time has
expired, the client will send a DHCPREQUEST message to the DHCP server, asking to
extend the lease for the given configuration. The DHCP server will respond with a
DHCPACK message if it agrees to renew the lease.
If the requesting IP address in the DHCPREQUEST message is inconsistent with the
allocated IP address whose lease GRHVQ¶W expire, the DHCP server will respond with
a DHCPNAK message.
3. Releasing the IP Address
z When a DHCP client no longer needs the IP address assigned by a DHCP server, it
relinquishes the address by sending a DHCPRELEASE message to the DHCP server.
The address returns to the address pool for reassignment. Besides the DHCP client
sets its IP address to 0.0.0.0.
7.8.1.3 DHCP Message types
DHCP is built on a client/server model. A client and a server may exchange the types of
messages listed in the below table.
Message Type Description
DHCPDISCOVER Broadcast by a client to find available DHCP servers.
DHCPOFFER
Response from a server to a DHCPDISCOVER message and offering IP
address and other parameters.
DHCPREQUEST
Message from a client to servers that does one of the following:
Ɣ Requests the parameters offered by one of the servers, which implicitly
declines all other offers.
Ɣ Requests the extension of a lease on a particular address.
Ɣ Verifies a previously allocated address after a system or network change
(a restart for example).