DHCP and BOOTP Relay

DHCP/BOOTP relay functionality is applied with the help of UDP broadcast forwarding. A typical situation occurs when a host requests an IP address with no DHCP server located on that segment. A routing module can forward the DHCP request to a server located on another network if:

• UDP broadcast forwarding is enabled
• The address of the DHCP server is configured as a helper address on the receiving interface

The DHCP/BOOTP relay agent function will detect the DHCP request and make the necessary changes to the header, replacing the destination address with the address of the server and the source with its own address, and then send it to the server. When the response comes from the server, the DHCP/BOOTP relay function sends it to the host.

Use the ip helper-address command in conjunction with the ip forward-protocol command to configure DHCP/BOOTP relay functionality to the specified server(s).