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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
• 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.
• 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.
Command Attributes
• Timeout – Sets the aging time for dynamic entries in the ARP cache.
(Range: 300 - 86400 seconds; Default: 1200 seconds or 20 minutes)
• Proxy ARP – Enables or disables Proxy ARP for specified VLAN interfaces.
Web - Click IP, ARP, General. Set the timeout to a suitable value for the ARP cache,
enable Proxy ARP for subnetworks that do not have routing or a default gateway,
and click Apply.
Figure 3-120 ARP General
CLI - This example sets the ARP cache timeout for 15 minutes (i.e., 900 seconds),
and enables Proxy ARP for VLAN 3.
Console(config)#arp-timeout 900 4-247
Console(config)#interface vlan 3 4-143
Console(config-if)#ip proxy-arp 4-248
Console(config-if)#