DHCPv4 & DHCPv6 Relay

DHCP requests are broadcast traffic. Broadcast traffic is limited to the broadcast domain where it is initiated. To provide DHCP service on a network segment without a DHCP server, use the DHCP relay to forward those requests to a defined server on another segment.

Warning

It is not possible to run both a DHCP server and a DHCP Relay at the same time. To enable the DHCP relay, first disable the DHCP server on each interface.

To configure the DHCP Relay:

  • Disable the DHCP Server on every interface

  • Navigate to Services > DHCP Relay

  • Click the tab for the interface to use with DHCP Relay

  • Configure the options as follows:

    Enable DHCP Relay

    Checked

    Append circuit ID and agent ID to requests

    Check this to add a circuit ID (pfSense® interface number) and the agent ID to the DHCP request. This may be required by the DHCP server on the other side, and can help distinguish where the requests originated.

    Destination Server

    A manual entry box to set the target DHCP server

  • Click Save

The DHCPv6 Relay function works identically to the DHCP Relay function for IPv4.