Cisco Unified Wireless Ap Requirements - Cisco 9971 Administration Manual

VoIP Wireless Network Components
Administration, to provide wireless voice communication. Cisco Access Points can run in standalone or unified
mode. Unified mode requires the Cisco Unified Wireless LAN Controller.
The Cisco Unified IP Phone 9971 exhibits Wi-Fi capabilities which can be used with 802.11a, 802.11b, and
802.11g Wi-Fi.
The following figure shows a typical WLAN topology that enables the wireless transmission of voice for
wireless IP telephony.
Figure 1: WLAN with Wireless IP Phones

Cisco Unified Wireless AP Requirements

APs are critical components in a WLAN because they provide the wireless links or " hot spots " to the network.
When a Cisco Unified IP Phone powers on, it searches for and becomes associated with an access point (AP)
if the phone wireless access is set to On. The Cisco Unified IP Phone scans for APs with SSIDs and encryption
types that it recognizes. The phone builds and maintains a list of eligible APs and uses the following variables
to determine the best AP:
• Received Signal Strength Indicator (RSSI): Signal strength of available APs within the RF coverage
area. The phone attempts to associate with the AP with the highest RSSI value and lowest channel usage
values (QBSS) that possess matching SSID and encryption types.
• Traffic Specification (TSpec): Calculation of call limits and WLAN load balancing. The TSpec value
of each voice stream allows the system to allocate bandwidth to voice devices on a first-come, first-served
basis.
APs transmit and receive RF signals over channels within the 2.4 GHz or 5 GHz frequency band. To provide
a stable wireless environment and reduce channel interference, you must specify nonoverlapping channels
for each AP. The recommended channels for 802.11b and 802.11g in North America are 1, 6, and 11.
Note In a non-controller-based wireless network, we recommend that you statically configure channels for each
AP. If your wireless network uses a controller, use the Auto-RF feature for minimal voice disruption.
Cisco Unified IP Phone 8961, 9951, and 9971 Administration Guide for Cisco Unified Communications Manager
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