Extreme Networks Altitude 3500 Series, Product Reference Manual

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Network Management
Altitude 3500 Series Access Point Product Reference Guide
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5 Refer to the QBSS Load Element Setting field to optionally allow the access point to communicate
channel usage data to associated devices and define the beacon interval used for channel utilization
transmissions. The QBSS load represents the percentage of time the channel is in use by the access
point and its station count. This information is very helpful in assessing the access point’s overall
load on the channel, its availability for additional device associations and multi media traffic
support.
Select the Enable QBSS load element checkbox (its selected by default) to enable the access point to
communicate channel usage to MUs. Access points with high channel usage may not be able to
process real-time traffic effectively. Therefore, VOIP phones can use the QBSS value to determine
whether a different access point association can provide better wireless support, since the QBSS
network load is reduced as additional access points are added.
If QBSS is enabled, define a QBSS Beacon Interval to define the beacon time (in seconds) the access
point uses to broadcast channel utilization information. This information should be periodically
accessed, as the access point’s network load will fluctuate throughout the day.
6 Configure the Performance field to set the preamble, thresholds values and QoS values for the radio.
Beacon Interval The beacon interval controls the performance of power
save stations. A small interval may make power save
stations more responsive, but it will also cause them to
consume more battery power. A large interval makes
power save stations less responsive, but could increase
power savings. The default is 100. Avoid changing this
parameter as it can adversely affect performance.
DTIM Interval The DTIM interval defines how often broadcast frames are
delivered for each of the four access point BSSIDs. If a
system has an abundance of broadcast traffic and it needs
to be delivered quickly, Extreme Networks recommends
decreasing the DTIM interval for that specific BSSID.
However, decreasing the DTIM interval decreases the
battery life on power save stations. The default is 10 for
each BSSID. Extreme Networks recommends using the
default value unless qualified to understand the
performance risks of changing it.
Support Short
Preamble The preamble is approximately 8 bytes of packet header
generated by the Altitude 35xx and attached to the packet
prior to transmission from the 802.11b radio. The preamble
length for 802.11b transmissions is data rate dependant.
The short preamble is 50% shorter than the long
preamble. Leave the checkbox unselected if in a mixed
MU/AP environment, as MUs and the Altitude 35xx are
required to have the same RF Preamble settings for
interoperability. The default is Disabled. The preamble
length for 802.11a and 802.11g transmissions is the same,
with no long or short preamble lengths.
RTS Threshold RTS allows the Altitude 35xx to use RTS (Request To
Send) on frames longer than the specified length.
The
default is 2341bytes.