It 'a network layer protocol (layer 3) and joins ICMP and IP. E'necessary for the operation of IP, as it has the task of assigningto each IP address, the corresponding MAC between the host of asame network. The MAC belongs to the machine, while IP isassigned by the network. Each machine has an internal IP ArpRegister that stores all known IP-MAC bindings. If A has to send a packet to B, which knows only the IP address:
-A sends a broadcast ARP request with the IP address of whomwant to know the MAC
-everyone receives the request and check if someone has thatIP-MAC binding
-B replies to A with an ARP Reply with the MAC address of B. Ifno one answers, the router responds with its MAC, as you would find that B is not part of the network.
A torque-saving IP-MAC in its register for a default TTL.
It has the same format as ARP, calmbia only field operation. If you want to know B's IP address and knows his MAC:
-A broadcasts a packet-level two-type RARP request
-The RARP server respond with a unicast Layer 2
-A receives the response and takes account of the first.