Qos Queues And Dscp On Packets - D-Link DWS-3000 Series User Manual

D-Link Unified Access System
each queue based on the requirements of the media being sent. Queues automatically provide minimum transmission delay
for Voice, Video, multimedia, and mission critical applications, and rely on best-effort parameters for traditional IP data.
For example, time-sensitive Voice, Video, and multimedia are given effectively higher priority for transmission (lower wait
times for channel access), while other applications and traditional IP data which are less time-sensitive but often more data-
intensive are expected to tolerate longer wait times.
The D-Link Unified Access System implements QoS based on the IEEE Wireless Multimedia (WMM) standard. A Linux-
based queuing class is used to tag packets and establish multiple queues. The queues provided offer built-in prioritization
and routing based on the type of data being transmitted.
The Administration UI provides a way for you to configure parameters on the queues.
Q S Q
O UEUES AND
QoS on the D-Link Unified Access System leverages
Point (DSCP). Every IP packet sent over the network includes a DSCP field in the header that indicates how the data should
be prioritized and transmitted over the network. The DSCP field consists of a 6 bit value defined by the local administration.
For WMM, Wi-Fi Alliance suggests a particular mapping for DSCP values
The access point examines the DSCP field in the headers of all packets that pass through the AP. Based on the value in a
packet's DSCP field, the AP prioritizes the packet for transmission by assigning it to one of the queues. This process occurs
automatically, regardless of whether you deliberately configure QoS or not.
A different type of data is associated with each queue. The queue and associated priorities and parameters for transmission
are as follows:
• Data 0 (Voice). Highest priority queue, minimum delay. Time-sensitive data such as Voice over IP (VoIP) is
automatically sent to this queue.
• Data 1 (Video). High priority queue, minimum delay. Time-sensitive data such as Video and other streaming media are
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).
Using the QoS settings in the AP profile, you can configure Enhanced Distributed Channel Access (EDCA) parameters that
determine how each queue is treated when it is sent by the access point to the client or by the client to the access point.
Wireless traffic travels:
• Downstream from the access point to the client station
• Upstream from client station to access point
• Upstream from access point to network
• Downstream from network to access point
With WMM enabled, QoS settings on the D-Link Unified Access System affect the first two of these; 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).
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).
Page 228
DSCP P
ON ACKETS
WMM information in the IP packet header related to Diff-Serv Code
Software User Manual
02/15/2011
Document 34CS3000-SWUM104-D10