Transmitting Packets to Remote Segments Continued
Packets will be transferred around the internetwork until the TTL (hop count) reaches its maximum. This is called indirect routing.
When a source computer does not know the address of a router that is remote, it can issue an ARP request for that device.
If the local router is aware of the non-local router’s MAC address, the local router can issue an ARP reply to the source of the ARP request.
In this way, the router acts as a Proxy ARP for the device on its local segment.