Cisco Systems 0L-11350-01 Configuring Client ARP Caching

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Cisco IOS Software Configuration Guide for Cisco Aironet Access Points

OL-11350-01

Chapter5 Administering the Access PointW ireless Device Access

Configuring Client ARP Caching

Note The SSH feature in this software release does not support IP Security (IPSec).

Before configuring SSH, download the crypto software image from Cisco.com. For more information,

refer to the release notes for this release.

For information about configuring SSH and displaying SSH settings, refer to Part 5, “Other Security

Features” in the Cisco IOS Security Configuration Guide for Release 12.3, which is available on

Cisco.com at the following link:

http://www.cisco.com/en/US/products/sw/iosswrel/ps5187/products_installation_and_configuration_g

uides_list.html

Configuring Client ARP Caching

You can configure the wireless device to maintain an ARP cache for associated client devices.

Maintaining an ARP cache on the wireless device reduces the traffic load on your wireless LAN. ARP

caching is disabled by default.

This section contains this information:

•Understanding Client ARP Caching, page 5-26

•Configuring ARP Caching, page 5-27

ARP caching on the wireless device reduces the traffic on your wireless LAN by stopping ARP requests

for client devices at the wireless device. Instead of forwarding ARP requests to client devices, the

wireless device responds to requests on behalf of associated client devices.

When ARP caching is disabled, the wireless device forwards all ARP requests through the radio port to

associated clients, and the client to which the ARP request is directed responds. When ARP caching is

enabled, the wireless device responds to ARP requests for associated clients and does not forward

requests to clients. When the wireless device receives an ARP request for an IP address not in the cache,

the wireless device drops the request and does not forward it. In its beacon, the wireless device includes

an information element to alert client devices that they can safely ignore broadcast messages to increase

battery life.

When a non-Cisco client device is associated to an access point and is not passing data, the wireless

device might not know the client’s IP address. If this situation occurs frequently on your wireless LAN,

you can enable optional ARP caching. When ARP caching is optional, the wireless device responds on

behalf of clients with IP addresses known to the wireless device but forwards out its radio port any ARP

requests addressed to unknown clients. When the wireless device learns the IP addresses for all

associated clients, it drops ARP requests not directed to its associated clients.