Cisco UNIFIED 9971, Deployment Manual

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Cisco Unified IP Phone 9971 Wireless LAN Deployment Guide
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Configuring Data Rates
It is recommended to disable rates below 12 Mbps for 5 GHz deployments and below 12 Mbps for 2.4 GHz deployments where
capacity and range are factored in for best results.
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.
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 mandatory / basic rate.
The recommended data rate configurations are the following:
802.11 Mode Mandatory (Basic)
Data Rates
Supported (Optional)
Data Rates
Disabled
Data Rates
802.11a 12 Mbps 18-24, <36-54> Mbps 6, 9, <36-54> Mbps
802.11b 11 Mbps None 1, 2, 5.5 Mbps
802.11b/g 11 Mbps 12-24, <36-54> Mbps 1, 2, 5.5, 6, 9, <36-54> Mbps
802.11g 12 Mbps 18-24, <36-54> Mbps 1, 2, 5.5, 6, 9, 11, <36-54>
Mbps
For a voice only application, 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 and enabling these rates could potentially increase the number
of retries for a data frame.
If deploying in an environment where excessive retries may be a concern, then a limited set of the data rates can be used (e.g.
12, 24, 54), where the lowest enabled rate is the mandatory / basic rate.
For rugged environments or deployments requiring maximum range, it is recommended to enable 6 Mbps as a mandatory /
basic rate.
To preserve high capacity and throughput, data rates of 24 Mbps and higher only can be enabled (24-54 Mbps).
Other applications such as video may be able to benefit from having these higher data rates enabled.
Note: Some environments may require that a lower data rate be enabled due to use of legacy clients, environmental factors or
maximum range is required.
Set only the lowest data rate enabled as the single mandatory / basic rate. Multicast packets will be sent at the highest
mandatory / basic data rate enabled.
Note that capacity and throughput are reduced when lower rates are enabled.
If Call Admission Control (TSPEC) is enabled then the Traffic Stream Rate Set (TSRS) feature will also be enabled, which can
allow lower rates to be enabled for legacy devices, while preventing the Cisco Unified IP Phone 9971 from transmitting at rates
below 12 Mbps for 802.11a and 11 Mbps for 802.11b/g as well as not above 24 Mbps if the Restricted Data Rates feature in
Cisco Unified Communications Manager is enabled. Disallowing packets to be transmitted at lower rates preserves capacity.
Sending voice frames at a more reliable rate (i.e. 24 Mbps) initially can potentially reduce the number of retries of a frame to
ensure the packet transmission is successful on the first try.
See the
Product Specific Configuration Options section for information on how to configure the Restrict Data Rates options on
the Cisco Unified IP Phone 9971 in order to utilize the TSRS feature.