ARP

ARP is a communication protocol used for discovering the link layer address, such as a MAC address, associated with a given internet layer address, typically an IPv4 address. This mapping is a critical function in the Internet protocol suite. ARP was defined in 1982 by RFC 826 which is Internet Standard STD 37.

In Internet Protocol Version 6 (IPv6) networks, the functionality of ARP is provided by the Neighbor Discovery Protocol (NDP).

To manipulate or display ARP table entries, the following commands are implemented.

Configure

set protocols static arp interface <interface> address <host> mac <mac>

This will configure a static ARP entry always resolving <address> to <mac> for interface <interface>.

Example:

set protocols static arp interface eth0 address 192.0.2.1 mac 01:23:45:67:89:01

Operation

show protocols static arp

Display all known ARP table entries spanning across all interfaces

vyos@vyos:~$ show protocols static arp
Address                  HWtype  HWaddress           Flags Mask     Iface
10.1.1.1                 ether   00:53:00:de:23:2e   C              eth1
10.1.1.100               ether   00:53:00:de:23:aa   CM             eth1

show protocols static arp interface eth1

Display all known ARP table entries on a given interface only (eth1):

vyos@vyos:~$ show protocols static arp interface eth1
Address                  HWtype  HWaddress           Flags Mask     Iface
10.1.1.1                 ether   00:53:00:de:23:2e   C              eth1
10.1.1.100               ether   00:53:00:de:23:aa   CM             eth1