Allied Telesis AlliedWare Plus Operating System Version 5.4.4C (x310-26FT,x310-26FP,x310-50FT,x310-50FP) - Manual (Page 627)

Internet Protocol (IP) Addressing and Protocols
Software Reference for x310 Series Switches
C613-50046-01 REV A AlliedWare Plus TM Operating System - Version 5.4.4C 24.3
Address Resolution Protocol (ARP)
Address Resolution Protocol (ARP) is used by your device to dynamically learn the Layer 2
address of devices in its networks. Most hosts also have a MAC physical address in addition
to the assigned IP address. For Ethernet, this is a 6-byte, globally unique number. ARP
enables your device to learn the physical address of the host that has a given IP address.
When your device needs to forward packets to a destination that it does not know the
Layer 2 address of, it broadcasts an ARP request to determine where to send the packet.
The ARP request is a broadcast packet and includes the target IP address. All stations on
the LAN receive this broadcast but only one host recognizes its own IP address. It replies,
thereby giving your device its physical address.
Your device creates a dynamic ARP entry in its ARP cache, to record the IP address to
physical address mapping (also called a binding). It uses that ARP entry to forward further
packets to that address.
The ARP protocol is described in RFC 826, An Ethernet Address Resolution Protocol—
or—Converting Network Protocol Addresses to 48 bit Ethernet Address for
Transmission on Ethernet Hardware.
Static ARP Entries
If your LAN includes hosts that do not support ARP, you can add a static ARP entry to the
cache. However, it is rarely necessary to add an ARP entry this way. To add a static ARP
entry, use the command:
Timing Out ARP Entries
Your device times out dynamic ARP entries to ensure that the cache does not fill with
entries for hosts that are no longer active. If your device stops receiving traffic for a device
specified in a dynamic ARP entry, it deletes the ARP entry after a configurable timeout
period. Static ARP entries are not aged or automatically deleted.
Increasing the ARP timeout reduces the amount of network traffic. Decreasing the
timeout makes your device more responsive to changes in network topology.
To set a timeout period, enter the interface mode, then use the command:
awplus(config)# arp <ip-addr> <mac-address> [<port-number>]
[alias]
awplus(config-if)# arp-aging-timeout <0-432000>