Cisco Cisco Access Registrar 4.2 Especificaciones descargar pdf (Pagina 147)

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Cisco Wireless LAN Controller Configuration Guide

OL-13826-01

Chapter 4 Configuring Controller SettingsWireless Device Access

Configuring Voice and Video Parameters

The QoS setting for a WLAN determines the level of bandwidth-based CAC support. To use

bandwidth-based CAC with voice applications, the WLAN must be configured for Platinum QoS. To use

bandwidth-based CAC with video applications, the WLAN must be configured for Gold QoS. Also,

make sure that WMM is enabled for the WLAN. See the “Configuring 802.3 Bridging” section on

page 4-29 for QoS and WMM configuration instructions.

Note You must enable admission control (ACM) for CCXv4 clients that have WMM enabled. Otherwise,

bandwidth-based CAC does not operate properly.

Load-Based CAC

Load-based CAC incorporates a measurement scheme that takes into account the bandwidth consumed

by all traffic types (including that from clients), co-channel access point loads, and co-located channel

interference, for voice applications. Load-based CAC also covers the additional bandwidth consumption

resulting from PHY and channel impairment.

In load-based CAC, the access point continuously measures and updates the utilization of the RF channel

(that is, the percentage of bandwidth that has been exhausted), channel interference, and the additional

calls that the access point can admit. The access point admits a new call only if the channel has enough

unused bandwidth to support that call. By doing so, load-based CAC prevents over-subscription of the

channel and maintains QoS under all conditions of WLAN loading and interference.

Note Load-based CAC is supported only on lightweight access points (except the Cisco Aironet 1500 series

access points, which support only bandwidth-based CAC). If you enable load-based CAC in a network

that contains a mixture of AP1500s and other lightweight access points, the AP1500s use

bandwidth-based CAC while the other lightweight access points used load-based CAC. If you disable

load-based CAC, all of the access points start using bandwidth-based CAC.

Expedited Bandwidth Requests

The expedited bandwidth request feature enables CCXv5 clients to indicate the urgency of a WMM

traffic specifications (TSPEC) request (for example, an e911 call) to the WLAN. When the controller

receives this request, it attempts to facilitate the urgency of the call in any way possible without

potentially altering the quality of other TSPEC calls that are in progress.

You can apply expedited bandwidth requests to both bandwidth-based and load-based CAC. Expedited

bandwidth requests are disabled by default. When this feature is disabled, the controller ignores all

expedited requests and processes TSPEC requests as normal TSPEC requests.

See Table 4-2 for examples of TSPEC request handling for normal TSPEC requests and expedited

bandwidth requests.

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Cisco Cisco Access Registrar 4.2 Especificaciones Pagina 147