Configuring the gateway
If the devices to be automatically configured and the servers for automatic configuration reside in different network segments, you must perform the following tasks:
Deploy a gateway and make sure the devices can communicate with the servers.
Configure the DHCP relay agent feature on the gateway.
Configure the UDP helper feature on the gateway.
When a device sends a request through a broadcast packet to the file server, the UDP helper changes the broadcast packet to a unicast packet and forwards the unicast packet to the file server. For more information about UDP helper, see Layer 3—IP Services Configuration Guide.