Roaming; Configuring Data Rates - Cisco 7925G Deployment Manual

Roaming

When using 802.1x type authentication, it is recommended to implement CCKM to enable fast roaming. 802.1x can introduce
delay during roaming due to its requirement for full re-authentication. CCKM centralizes the key management and reduces the
number of key exchanges. WPA introduces additional transient keys and can lengthen roaming time.
The Cisco Unified Wireless IP Phone 7925G supports CCKM with WPA (TKIP) and 802.1x (WEP) authentication.
CCKM with WPA (AES) or WPA2 (TKIP/AES) are not supported as of the 1.3(3) release.
Authentication
Open
802.1x
WPA Personal
WPA Enterprise
CCKM

Configuring Data Rates

It is recommended to disable rates below 12 Mbps for 802.11a and below 12 Mbps for 802.11b/g deployments where capacity
and range are factored in for best results.
If 802.11b clients are not allowed in the wireless LAN, then it is recommended to disable the 1, 2, 5.5, 11 Mbps data rates.
When 802.11b clients exist in the wireless network, then an 802.11b rate must be enabled and only an 802.11b rate can be
configured as a basic rate. In this case, is suggested to enable the data rates 11 Mbps and higher.
If using Coexistence where 802.11b/g and Bluetooth are being used simultaneously, then the data rates below 11 Mbps should
be disabled. If 802.11b clients are not allowed in the wireless network, then it is strongly recommended to disable the data rates
below 12 Mbps. This will eliminate the need to send CTS frames for 802.11g protection as 802.11b clients can not detect these
OFDM frames.
The recommended data rate configuration is the following:
802.11 Mode
802.11a
802.11b
802.11g
802.11b/g
Data rates higher than 24 Mbps (36, 48 and 54 Mbps) can optionally be enabled or disabled, but there is no advantage from a
capacity or throughput perspective to enable these rates for a voice application.
Enabling these rates could potentially increase the number of retries for a data frame.
Other applications may be able to benefit from having these higher data rates enabled.
Cisco Unified Wireless IP Phone 7925G Deployment Guide
Roaming Time
< 100 ms
300 ms
400 ms
400 – 500 ms
< 100 ms
Basic (Mandatory)
Data Rates
12 Mbps
11 Mbps
12 Mbps
11 Mbps
Supported (Optional)
Data Rates
18 - 24, <36-54> Mbps
None
18 – 24, <36-54> Mbps
12 – 24, <36-54> Mbps
Disabled
Data Rates
6, 9, <36-54> Mbps
1, 2, 5.5 Mbps
6, 9, <36-54> Mbps
1, 2, 5.5, 6, 9, <36-54> Mbps
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