Cisco Systems DL-2159-05 manual Use Aironet Extensions

Chapter 3 Radio Configuration and Basic Settings

Radio Configuration

Use Aironet Extensions

Select yes or no to use Cisco Aironet 802.11 extensions. This setting must be set to yes (the default setting) to enable these features:

•Load balancing—The access point uses Aironet extensions to direct client devices to an access point that provides the best connection to the network based on factors such as number of users, bit error rates, and signal strength.

•Message Integrity Check (MIC)—MIC is an additional WEP security feature that prevents attacks on encrypted packets called bit-flipattacks. The MIC, implemented on both the access point and all associated client devices, adds a few bytes to each packet to make the packets tamper-proof.

•Temporal Key Integrity Protocol (TKIP)—TKIP, also known as WEP key hashing, is an additional WEP security feature that defends against an attack on WEP in which the intruder uses an unencrypted segment called the initialization vector (IV) in encrypted packets to calculate the WEP key.

•Repeater mode—You must set Use Aironet Extensions to yes if the access point is set up as a repeater or if it communicates with a repeater.

The extensions also improve the access point’s ability to understand the capabilities of Cisco Aironet client devices associated with the access point.

Note If you enable this feature, you must manually reboot the access point to have the settings take affect.

Classify Workgroup Bridges as Network Infrastructure

Select no to allow more than 20 Cisco Aironet Workgroup Bridges to associate to the access point. The default setting, yes, limits the number of workgroup bridges that can associate to the access point to 20.

The Reliable multicast messages from the access point to workgroup bridges setting limits reliable delivery of multicast messages to approximately 20 Cisco Aironet Workgroup Bridges that are associated to the access point. The default setting, disabled, reduces the reliability of multicast delivery to enable more workgroup bridges to associate to the access point.

Access points and bridges normally treat workgroup bridges not as client devices but as infrastructure devices, like access points or bridges. Treating a workgroup bridge as an infrastructure device means that the access point reliably delivers multicast packets, including Address Resolution Protocol (ARP) packets, to the workgroup bridge.

The performance cost of reliable multicast delivery—duplication of each multicast packet sent to each workgroup bridge—limits the number of infrastructure devices, including workgroup bridges, that can associate to the access point. To increase beyond 20 the number of workgroup bridges that can maintain a radio link to the access point, the access point must reduce the delivery reliability of multicast packets to workgroup bridges. With reduced reliability, the access point cannot confirm whether multicast packets reach the intended workgroup bridge, so workgroup bridges at the edge of the access point's coverage area might lose IP connectivity. When you treat workgroup bridges as client devices, you increase performance but reduce reliability.

Note This feature is best suited for use with stationary workgroup bridges. Mobile workgroup bridges might encounter spots in the access point’s coverage area where they do not receive multicast packets and lose communication with the access point even though they are still associated to it.

Cisco Aironet 1200 Seres Access Point Software Configuration Guide

OL-2159-05 3-19