Cisco Unified Wireless IP Phone 7925G Series Deployment Guide
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Configuring QoS Basic Service Set (QBSS)
There are three different versions of QoS Basic Service Set (QBSS) that the Cisco Unified Wireless IP Phone 7925G Series
supports.
The first version from Cisco was on a 0-100 scale and was not based on clear channel assessment (CCA), so it does not account
for channel utilization, but only the 802.11 traffic traversing that individual access point’s radio. So it does not account for
other 802.11 energy or interferers using the same frequencies. The max threshold is defined on the client side, which is set to
45. This would allow for up to 7 calls at 11 Mbps plus some background traffic.
QBSS is also a part of 802.11e, which is on a 0-255 scale and is CCA based. So this gives a true representation on how busy
the channel is. The max threshold is also defined on the client side, which is set to 105.
The second version from Cisco is based on the 802.11e version, but allows the default max threshold of 105 to be optionally
configured.
Each version of QBSS can be optionally be configured on the access point.
For the Cisco Unified Wireless LAN Controller, enabling WMM will enable the 802.11e version of QBSS. There are also the
“7920 Client CAC”
and
“7920 AP CAC”
options, where
“7920 Client CAC”
will enable Cisco version 1 and
“7920 AP
CAC”
enables Cisco version 2. See the “
SSID / WLAN QoS Settings
” section for more info.
For the Cisco Autonomous Access Point,
“dot11 phone”
or
“dot11 phone dot11e”
will enable QBSS.
“Dot11 phone”
will enable the 2 Cisco versions, where
“dot11 phone dot11e”
will enable both CCA versions (802.11e and
Cisco version 2). It is recommended to enable
“dot11 phone dot11e”
.
