The dhcp server identifier dest-ip command enables the DHCP server to use the destination IP address in the packet forwarded by the DHCP relay as the server identifier.
The undo dhcp server identifier command restores the default configuration.
By default, the DHCP server uses the inbound interface IP address in a DHCP request as the server identifier.
Usage Scenario
This command is used when a DHCP client is connected to a DHCP relay (first PE) over a VPN and the DHCP relay sends a DHCP request to the DHCP server (second PE). The DHCP server assigns an IP address to the DHCP client over the VPN.
The server IP address specified by the DHCP server is generally the IP address of a non-public interface on the DHCP server, but the DHCP request is received by a public interface on the DHCP server. By default, the DHCP server uses the inbound interface IP address in the DHCP request (public interface IP address) as the server identifier. As a result, the DHCP client fails to extend the lease. To address this problem, run the dhcp server identifier dest-ip command to enable the DHCP server to use the destination IP address in the packet forwarded by the DHCP relay as the server identifier.