Allied Telesis AT-WA7400/NA - Manual (Page 162)

Chapter 15: Configuring Quality of Service (QoS)
162
Understanding QoS
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 such as 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.
QoS and Load
Balancing
By using a combination of load balancing (see Chapter 14, “Load
Balancing” on page 155) and QoS techniques, you can provide a high
quality of service for time-sensitive applications even on a busy network.
Load balancing is a way of better distributing the traffic volume across
access points. 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.
802.11e and
WMM Standards
Support
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 AT-WA7400 Management Software provides QoS based on the
wireless multimedia (
WMM ) specification and wireless multimedia (WMM)
standards, which are implementations of a subset of 802.11e features.
Both access points and wireless clients (laptops, consumer electronics
products, and so forth) can be WMM-enabled.
QoS Queues and
Parameters to
Coordinate
Traffic Flow
Configuring QoS options on the AT-WA7400 Wireless Access Point
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