Changes

The <b>Address Resolution Protocol</b> (<b>ARP</b>) is a communication protocol used for mapping an Internet Protocol address (IP address) to a physical machine's link layer address (MAC address) belonging to the local network.

The <b>Address Resolution Protocol</b> (<b>ARP</b>) is a communication protocol used for mapping an Internet Protocol address (IP address) to a physical machine's link layer address (MAC address) belonging to the local network.

The ARP section displays the router's <b>ARP cache</b> (also known as ARP table) data. The ARP cache is used to maintain a correlation between each MAC address and its corresponding IP address. ARP provides the protocol rules for making this correlation and providing address conversion in both directions.

The ARP section displays the router's <b>ARP cache</b> (also known as ARP table) data. The ARP cache contains information on each known MAC address and its corresponding IP address. When the router receives a packet destined for a local host, the ARP program attempts to find a physical host or MAC address in the ARP cache that matches the IP address. If the ARP cache doesn't contain the needed IP address, ARP broadcasts a request packet to all LAN machines in order to find the device with the IP address in question.

When an incoming packet destined for a host machine on a particular local area network arrives at a gateway, the gateway asks the ARP program to find a physical host or MAC address that matches the IP address. The ARP program looks in the ARP cache and, if it finds the address, provides it so that the packet can be converted to the right packet length and format and sent to the machine. If no entry is found for the IP address, ARP broadcasts a request packet in a special format to all the machines on the LAN to see if one machine knows that it has that IP address associated with it. A machine that recognizes the IP address as its own returns a reply so indicating. ARP updates the ARP cache for future reference and then sends the packet to the MAC address that replied.

The figure below is an example of the ARP cache section:

[[File:{{{file_arp}}}]]

[[File:{{{file_arp}}}]]

You can also vie the ARP cache via shell using the <b>arp</b> or <b>ip neigh</b> commands, depending on which output your prefer:

You can also view the ARP cache via shell using the <b>arp</b> or <b>ip neigh</b> commands, depending on which output your prefer:

  root@Teltonika-{{{name}}}:~# <b>arp</b>

  root@Teltonika-{{{name}}}:~# <b>arp</b>