Publication date:March., 2011Revision A1463-3. DHCP RelayThe Dynamic Host Configuration Protocol (DHCP) is a service that runs at theapplication layer of the TCP/IP protocol stack to dynamically assign IP addresses toDHCP clients. DHCP clients request IP addresses, and obtain leases for IPaddresses from the DHCP server.The DHCP Relay Agent makes it possible for DHCP broadcast messages tobe sent over routers that do not support forwarding of these types of messages. TheDHCP Relay Agent is therefore the routing protocol that enables DHCP clients toobtain IP addresses from a DHCP server on a remote subnet, or which is notlocated on the local subnet. If you have no configured DHCP Relay Agent, yourclients would only be able to obtain IP addresses from the DHCP server which is onthe same subnet.If you are using the switches to insert DHCP Option 82 information and youare also using as DHCP relay-agents (via ‘ip helper-address’), you’ll notice rightaway that your Option 82 enabled DHCP requests are not being forwarded by yourswitches.Function name:ConfigFunction description:The switch to enable clients to obtain IP addresses from a DHCP server on aremote subnet, you have to configure the DHCP Relay Agent on the subnet thatcontains the remote clients, so that it can relay DHCP broadcast messages to yourDHCP server.Parameters description:DHCP Relay State:Fig. 3-13-1
