Here are the steps R1 needs to take before forwarding frames to Host A:
- R1 wants to communicate with Host A. R1 checks its routing table. The subnet on which Host A resides is a directly connected subnet.
- R1 checks its ARP table to find out whether the Host A’s MAC address is known. If it is not, R1 will send an ARP request to the broadcast MAC address of FF:FF:FF:FF:FF:FF.
- Host A receives the frame and sends its MAC address to R1 (ARP reply). The host also updates its own ARP table with the MAC address of the Gigabit0/0 interface on R1.
- R1 receives the reply and updates the ARP table with the MAC address of Host A.
- Since both hosts now know each other MAC addresses, the communication can occur.