Used in Layer-2 Switch to know the MAC Destination & used in Frame switching.
- ARP Request:
- When MAC is unknown, frame is broadcasted along the way until the destination has been found. This is the ARP “request”
- ARP Reply
- When MAC is found, frame is returned to the source to indicate the found device. Now it travels along the reverse path using addresses stored on Switches. This is called ARP “reply”.