Design Guide

Cisco Wireless IP Phone 8821 and 8821-EX Wireless LAN Deployment Guide
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High Throughput (802.11n/ac)
The 802.11n data rates can be configured per radio (2.4 GHz and 5 GHz).
802.11ac data rates are applicable to 5 GHz only.
Ensure that WMM is enabled and WPA2(AES) is configured in order to utilize 802.11n/ac data rates.
The Cisco Wireless IP Phone 8821 and 8821-EX support HT MCS 0 - MCS 7 and VHT MCS 0 - MCS 9 data rates only, but
higher MCS rates can optionally be enabled if there are other 802.11n/ac clients utilizing the same band frequency that include
MIMO antenna technology, which can take advantage of the those higher data rates.
It is recommended to disable MCS 0.
Frame Aggregation
Frame aggregation is a process of packaging multiple MAC Protocol Data Units (MPDUs) or MAC Service Data Units
(MSDUs) together to reduce the overheads where in turn throughput and capacity can be optimized.
Aggregation of MAC Protocol Data Unit (A-MPDU) requires the use of block acknowledgements.
It is recommended to adjust the A-MPDU and A-MSDU settings to the following to optimize the experience with the Cisco
Wireless IP Phone 8821 and 8821-EX.
A-MPDU
User Priority 0, 3, 4, 5 = Enabled
User Priority 1, 2, 6, 7 = Disabled
A-MSDU
User Priority 1, 2 = Enabled
User Priority 0, 3, 4, 5, 6, 7 = Disabled