Allied Telesis AT-S63 - Manual (Page 188)

Chapter 10: Networking Stack
188 Section I: Basic Operations
Managing the Address Resolution Protocol (ARP) Table
The switch has an Address Resolution Protocol (ARP) table for storing IP
addresses of network devices and their corresponding MAC addresses.
The switch uses the table whenever you issue a management command
that requires the switch’s AT-S63 management software to interact with
another device on the network. An example would be if you instructed the
switch to ping another network device or download a new AT-S63 image
file or configuration file from a TFTP server.
The value of the ARP table is that it eliminates the need of the switch to
issue unnecessary ARP broadcast packets when performing some
management functions. This can improve the switch’s response time as
well as reduce the number of broadcast packets on your network.
The table can hold up to 11 entries. There are two types of entries. One
type is permanent. There is only one permanent entry. It is used by the
switch for internal diagnostics and it can never be removed from the table.
The other type is a temporary entry, of which there can be up to ten. The
switch adds a temporary entry whenever its management software
interacts with another network device during a management function.
When you enter a management command that contains an IP address not
in the table, the switch sends out an ARP broadcast packet. When the
remote device responds with its MAC address, the switch adds the
device’s IP address and MAC address as a new temporary entry to the
table.
A temporary entry remains in the table only while active. An entry remains
active so long as it is periodically used by the switch for management
functions. If an entry is inactive for a specified period of time, referred to as
ARP cache timeout, it is automatically removed from the table. This value
is adjustable, as explained in “Setting the ARP Cache Timeout” on
page 192. The default is 400 seconds. If the table becomes full, the
management software continues to add new entries by deleting the oldest
entries.
The management software allows you to view the contents of the table.
You can also delete individual table entries or delete all the entries. These
functions are explained in the following subsections:
ˆ “Displaying the ARP Table” on page 189
ˆ “Deleting an ARP Table Entry” on page 191
ˆ “Resetting the ARP Table” on page 191
ˆ “Setting the ARP Cache Timeout” on page 192