IPv6 DHCP Relay Source and Destination Interfaces

By default the router interface that receives the DHCP request is the DHCP request source interface for the router. You can configure an always-up global source interface for the device such as a loop-back interface. The configured global source-interface can be overridden at the interface level.

Use the ipv6 dhcp relay source-interface command in global configuration mode to configure a global source interface for the router.

Use the ipv6 dhcp relay source-interface command in interface configuration mode to have the specified interface override the globally configured source interface for this interface.

The destination server interface must be specified when the DHCPv6 destination server address is either link-local or multicast IPv6. Specifying a destination interface is not required if the DHCPv6 destination server address is a global address.

The DHCP Solicit message is a multicast message to the all DHCP server address (ff02::1:2). The all DHCP server address only crosses network segments when explicitly routed. If your network has multiple segments, you must configure a DHCP relay agent on the router interface for each segment, so that all DHCP solicit messages can be forwarded to your DHCP server.

If a destination interface is not specified, because the DHCPv6 server address is a global address, the interface is determined by a standard routing table lookup.

Use the ipv6 dhcp relay destination command in interface configuration mode to configure the IPv6 DHCP relay agent to forward an IPv6 DHCP request from a client or other relay agent to the destination server or next relay agent address.