D-Link DGS-6600-48TS Configuration Guide - Page 500

Volume 9-Network Application / Chapter 50-DHCP Relay Configuration DHCP Relay Configuration Commands When a message is being relayed by the relay agent, several messages are exchanged between the relay agent and the DHCP server in the following sequence: 1) The client sends a DHCP message with a broadcast destination IP address. 2) The relay agent then intercepts the DHCP message, inserts the option-82 field in the message (if configured to do so), populates the gateway IP address field in the message with its own IP address, and sends a unicast message to the DHCP server. 3) When the DHCP server receives the message, the message is processed and a unicast reply message is sent to the relay agent. 4) When the relay agent receives the message, the option-82 field is removed from the message (if configured to do so) and the message is sent back to the client via a broadcast IP address. DHCP Relay Configuration Commands • Enabling the DHCP Relay Agent Service • Specifying the Maximum Number of DHCP Relay Hops • Specifying a DHCP Relay Address Enabling the DHCP Relay Agent Service Use the following command in global configuration mode to globally enable the relay agent on the Switch: Command ip dhcp relay Explanation Globally enables the DHCP relay agent service. In the following example, the user globally enables the DHCP relay agent service: DGS-6600:2>enable DGS-6600:15#configure terminal DGS-6600:15(config)#ip dhcp relay DGS-6600:15(config)#end Specifying the Maximum Number of DHCP Relay Hops A DHCP client may be relayed by relay agents over multiple hops before arriving at the DHCP server. The user can use the following command in global configuration mode to restrict the maximum number of relay agents that a DHCP message can traverse: Command ip dhcp relay hops HOP-COUNT Explanation Specifies the maximum number of relay agents that a DHCP message can traverse. DGS-6600 Configuration Guide 500