D-Link DWS-4026 User Manual page 520

D-Link Unified Access System
Field
Queue
AIFS
(Inter-Frame Space)
cwMin
(Minimum Contention
Window)
cwMax
(Maximum Contention
Window)
Max. Burst Length
WMM Mode
Page 520 Configuring Advanced Settings
Table 337: QoS Settings (Cont.)
Description
Queues are defined for different types of data transmitted from AP-to-station:
• Data 0 (Voice)—High priority queue, minimum delay. Time-sensitive data such as VoIP
and streaming media are automatically sent to this queue.
• Data 1(Video)—High priority queue, minimum delay. Time-sensitive video data is
automatically sent to this queue.
• Data 2 (best effort)—Medium priority queue, medium throughput and delay. Most
traditional IP data is sent to this queue.
• Data 3 (Background)—Lowest priority queue, high throughput. Bulk data that requires
maximum throughput and is not time-sensitive is sent to this queue (FTP data, for
example).
The Arbitration Inter-Frame Spacing (AIFS) specifies a wait time for data frames. The
wait time is measured in slots. Valid values for AIFS are 1 through 255.
This parameter is input to the algorithm that determines the initial random backoff wait
time (window) for retry of a transmission.
The value specified here in the Minimum Contention Window is the upper limit (in
milliseconds) of a range from which the initial random backoff wait time is determined.
The first random number generated will be a number between 0 and the number
specified here.
If the first random backoff wait time expires before the data frame is sent, a retry counter
is incremented and the random backoff value (window) is doubled. Doubling will
continue until the size of the random backoff value reaches the number defined in the
Maximum Contention Window.
Valid values for the cwmin are 1, 3, 7, 15, 31, 63, 127, 255, 511, or 1024. The value for
cwmin must be lower than the value for cwmax.
The value specified here in the Maximum Contention Window is the upper limit (in
milliseconds) for the doubling of the random backoff value. This doubling continues until
either the data frame is sent or the Maximum Contention Window size is reached.
Once the Maximum Contention Window size is reached, retries will continue until a
maximum number of retries allowed is reached.
Valid values for the cwmax are 1, 3, 7, 15, 31, 63, 127, 255, 511, or 1024. The value for
cwmax must be higher than the value for cwmin.
AP EDCA Parameter Only (The Max. Burst Length applies only to traffic flowing from
the access point to the client station.)
This value specifies (in milliseconds) the Maximum Burst Length allowed for packet
bursts on the wireless network. A packet burst is a collection of multiple frames
transmitted without header information. The decreased overhead results in higher
throughput and better performance.
Valid values for maximum burst length are 0.0 through 999.
General Parameters
Wi-Fi MultiMedia (WMM) is enabled by default. With WMM enabled, QoS prioritization
and coordination of wireless medium access is on. With WMM enabled, QoS settings on
the D-Link Unified Switch control downstream traffic flowing from the access point to
client station (AP EDCA parameters) and the upstream traffic flowing from the station to
the access point (station EDCA parameters).
Disabling WMM deactivates QoS control of station EDCA parameters on upstream
traffic flowing from the station to the access point
With WMM disabled, you can still set some parameters on the downstream traffic
flowing from the access point to the client station (AP EDCA parameters).
To disable WMM extensions, click Disabled.
To enable WMM extensions, click Enabled.
Software User Manual
Document 34CSFP6XXUWS-SWUM100-D7
12/10/09