Manual

AT-WA7400 Management Software User’s Guide
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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 AT-WA7400 Management Software 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.
AT-WA7400 Management Software provides a way for you to configure
parameters on the queues.
QoS Queues and Type of Service (ToS) on Packets
QoS on the AT-WA7400 Wireless Access Point leverages WMM
information in the IP packet header related to Type of Service (ToS ). Every
IP packet sent over the network includes a ToS field in the header that
indicates how the data should be prioritized and transmitted over the
network. The ToS field consists of a 3 to 7 bit value with each bit
representing a different aspect or degree of priority for this data as well as
other meta-information (low delay, high throughput, high reliability, low
cost, and so on).
For example, the ToS for FTP data packets is likely to be set for maximum
throughput because the critical consideration for FTP is the ability to
transmit relatively large amounts of data in one go. Interactive feedback is
nice to have in this situation but certainly less critical. VoIP data packets
are set for minimum delay because that is a critical factor in quality and
performance for that type of data.
The access point examines the ToS field in the headers of all packets that
pass through the access point. Based on the value in a packet’s ToS field,
the access point 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.