D-Link DWL-8600AP Administrator's Manual page 74

D-Link UAP
Field
cwMin
(Minimum Contention
Window)
cwMax
(Maximum Contention
Window)
Max. Burst Length
Wi-Fi Multimedia Settings
Wi-Fi MultiMedia
Station EDCA Parameters
Queue
AIFS
(Inter-Frame Space)
Page 74 Configuring Quality of Service (QoS)
Table 33: QoS Settings (Cont.)
Description
This parameter is input to the algorithm that determines the initial random backoff wait time
(window) for retry of a transmission.
The value specified for 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 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 for 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 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.
The Max. Burst Length is an AP EDCA parameter and only applies to traffic flowing from the
AP 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.
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 UAP
control downstream traffic flowing from the AP to client station (AP EDCA parameters) and the
upstream traffic flowing from the station to the AP (station EDCA parameters).
Disabling WMM deactivates QoS control of station EDCA parameters on upstream traffic
flowing from the station to the AP.
With WMM disabled, you can still set some parameters on the downstream traffic flowing from
the AP to the client station (AP EDCA parameters).
To disable WMM extensions, click Disabled.
To enable WMM extensions, click Enabled.
Queues are defined for different types of data transmitted from station-to-AP:
• Data 0 (Voice)—Highest priority queue, minimum delay. Time-sensitive data such as VoIP
and streaming media are automatically sent to this queue.
• Data 1 (Video)—Highest 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.
Software User Manual
12/10/09
34CSFP6XXUAP-SWUM100-D13