Hop count in DHCP requests

When a DHCP client broadcasts requests, the DHCP relay agent in the routing switch receives the packets and forwards them to the DHCP server (on a different subnet, if necessary.) During this process, the DHCP relay agent increments the hop count before forwarding DHCP packets to the server. The DHCP server, in turn, includes the hop count from the received DHCP request in the response sent back to a DHCP client.

As a result, the DHCP client receives a non-zero hop count in the DHCP response packet. Because some legacy DHCP/BootP clients discard DHCP responses that contain a hop count greater than one, they may fail to boot up properly. Although this behavior is in compliance with RFC 1542, it prevents a legacy DHCP/BootP client from being automatically configured with a network IP address.