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Software User Manual D-Link Unified Access System
02/15/2011
Document 34CS3000-SWUM104-D10 Page 227
Appendix D: Understanding Quality of Service
Quality of Service ( QoS ) provides you with the ability to specify parameters on multiple queues for increased throughput and
better performance of differentiated wireless traffic like Voice-over-IP (VoIP), other types of audio, video, and streaming
media as well as traditional IP data over the D-Link Unified Access System.
A primary factor that affects QoS is network congestion due to an increased number of clients attempting to access the air
waves and higher traffic volume competing for bandwidth during a busy time of day. The most noticeable degradation in
service on a busy, overloaded network will be evident in time-sensitive applications like Video,
Voice-over-IP (VoIP), and
streaming media.
Unlike typical data files which are less affected by variability in QoS, Video, VoIP and streaming media must be sent in a
specific order at a consistent rate and with minimum delay between
Packet transmission. If the quality of service is
compromised, the audio or video will be distorted.
Q
O
S
AND
L
OAD
B
ALANCING
By using a combination of load balancing and QoS techniques, you can provide a high quality of service for time-sensitive
applications even on a busy network. Load balancing sets thresholds for client associations and AP utilization. QoS is a
means of allocating bandwidth and network access based on transmission priorities for different types of wireless traffic
within a single access point.
802.11
E AND
WMM S
TANDARDS
S
UPPORT
QoS describes a range of technologies for controlling data streams on shared network connections. The IEEE 802.11e task
group is in the process of defining a QoS standard for transmission quality and availability of service on wireless networks.
QoS is designed to provide better network service by minimizing network congestion; limiting
jitter, latency, and packet loss ;
supporting dedicated bandwidth for time-sensitive or mission critical applications, and prioritizing wireless traffic for channel
access.
As with all IEEE 802.11 working group standards, the goal is to provide a standard way of implementing QoS features so
that components from different companies are interoperable.
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.
C
OORDINATING
T
RAFFIC
F
LOW
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
Note: For the IEEE 802.11e, only Unscheduled Automatic Power Save Delivery (U-APSD), part of the 802.11e,
is supported when DWL-8600APs are managed by a DWS-3000 switch.