8. Interface Selection

8. Interface Selection

Delegated prefixes are not associated with a particular interface in the same way as addresses are for address assignment, and the rules described in section 16, "Client Source Address and Interface Selection" of RFC 3315 do not apply.

When a requesting router sends a DHCP message, it SHOULD be sent on the interface associated with the upstream router (ISP network). The upstream interface is typically determined by configuration. This rule applies even in the case where a separate IA_PD is used for each downstream interface.

When a requesting router sends a DHCP message directly to a delegating router using unicast (after receiving the Server Unicast option from that delegating router), the source address SHOULD be an address from the upstream interface and which is suitable for use by the delegating router in responding to the requesting router.