D-Link DWS-4026 Product Manual - Page 520

D-Link Unified Access System Software User Manual 12/10/09 Field Queue AIFS (Inter-Frame Space) cwMin (Minimum Contention Window) cwMax (Maximum Contention Window) Max. Burst Length WMM Mode 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. Page 520 Configuring Advanced Settings Document 34CSFP6XXUWS-SWUM100-D7