--dhcp-circuitid=set:<tag>,<circuit-id>, --dhcp-remoteid=set:<tag>,<remote-id>

Map from RFC3046 relay agent options to tags. This data may be provided by DHCP relay agents. The circuit-id or remote-id is normally given as colon-separated hex, but is also allowed to be a simple string. If an exact match is achieved between the circuit or agent ID and one provided by a relay agent, the tag is set.

--dhcp-remoteid (but not --dhcp-circuitid) is supported in IPv6.