D-Link DWS 3000 user manual Coordinating Traffic Flow, QoS Queues and Dscp on Packets

D-Link Unified Access System User Manual

The D-Link Access Points provide QoS based on the Wireless Multimedia (WMM) specification, which implements a subset of 802.11e features.

Both access points and wireless clients (laptops, consumer electronics products) can be WMM-enabled by the Wi-Fi Alliance.

Coordinating Traffic Flow

Configuring QoS options on the D-Link Unified Access System consists of setting parameters on existing queues for different types of wireless traffic. You can configure different minimum and maximum wait times for the transmission of packets in 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.

QoS Queues and DSCP on Packets

QoS on the D-Link Unified Access System leverages WMM information in the IP packet header related to Diff-Serv Code 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.

204 © 2001- 2006 D-Link Corporation/D-Link Systems, Inc. All Rights Reserved.