DHCP Relay

DHCP (Dynamic Host Configuration Protocol) Relay is used to transfer DHCP messages between clients and servers when they are on different subnet domains.

DHCP option 82 allows a DHCP relay agent to insert specific information into client request packets when they are forwarded to the DHCP server. When reply packets are sent to a DHCP client, the information will be removed. The DHCP server can use this information to implement IP addresses or other assignment policies. Specifically, the option works by setting two sub-options: Circuit ID (option 1) and Remote ID (option2). The Circuit ID includes information specific to the circuit where the request originated. The Remote ID carries information about the remote host.