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Command Attributes
• Timeout – Sets the aging time for dynamic entries in the ARP cache.
(Range: 300 - 86400 seconds; Default: 1200 seconds or 20 minutes)
The ARP aging timeout can be set for any currently configured VLAN.
The aging time determines how long dynamic entries remain the cache. If the
timeout is too short, the router may tie up resources by repeating ARP requests for
addresses recently flushed from the table.
When a ARP entry expires, it is deleted from the cache and an ARP request packet
is sent to re-establish the MAC address.
• Proxy ARP – Enables or disables Proxy ARP for specified VLAN interfaces,
allowing a non-routing device to determine the MAC address of a host on another
subnet or network. (Default: Disabled)
End stations that require Proxy ARP must view the entire network as a single
network. These nodes must therefore use a smaller subnet mask than that used
by the router or other relevant network devices.
Extensive use of Proxy ARP can degrade router performance because it may lead
to increased ARP traffic and increased search time for larger ARP address tables.
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Basic ARP Configuration
You can use the ARP General configuration menu to specify the timeout for ARP
cache entries, or to enable Proxy ARP for specific VLAN interfaces.
Command Usage
Proxy ARP
When a node in the attached subnetwork does not have routing or a default gateway
configured, Proxy ARP can be used to forward ARP requests to a remote subnetwork.
When the router receives an ARP request for a remote network and Proxy ARP is
enabled, it determines if it has the best route to the remote network, and then
answers the ARP request by sending its own MAC address to the requesting node.
That node then sends traffic to the router, which in turn uses its own routing table to
forward the traffic to the remote destination.
Proxy ARP
ARP
request
no routing,
no default
gateway
Remote
A
RP Server
Address Resolution Protocol
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