A DHCP Relay agent relays DHCP requests from the client to the DHCP server and relays the DHCP replies from the server to the client. It acts as a proxy, thereby reducing the number of DHCP servers required in the network. The DHCP relay agent inserts its own IP address in the giaddr field (gateway address) of the DHCP request. The DHCP server can look into this IP address, identify the DHCP client‘s subnet and assign an IP address accordingly.

You can enable BOOTP Relay over VRFs and VPN-VRFs in the same manner as with normal VRs. Normally, you must enable BOOTP Relay on both ingress and egress VLANs. However, with BOOTP Relay over L3VPN, you do not need to enable BOOTP Relay on egress VLANs, since ingress and egress VLANs are present in different VRs/VRFs.


The following are limitations of the BOOTP Relay L3VPN feature:
  • VPN-ID is not supported on DHCP-Relay Option 82, which services clients across VPNs.
  • IPv6 BOOTP Relay not supported, since there is no IPv6 support for L3VPN.