Configuring the ECN330-switch
406 1553-KDU 137 365 Uen D 2006-06-16
6.20.5.1 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.
Figure 175 Proxy ARP
6.20.5.2 Basic ARP Configuration
The ARP General configuration menu can be used 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)
no routing,
no default
gateway
Remote
ARP Server
Proxy ARP
ARP
request
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