Quality of Service (QoS)
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QoS Overview
The AT-FS7000 Series Switches feature QoS based on the IEEE 802.1p
standard. QoS can be important to network environments when there
are time-critical applications, such as voice transmission or video
conferencing, that can be adversely affected by packet transfer delays.
When QoS is enabled, the switch will assign the ingress frames to either
high priority and low priority. The switch determines these priorities
based on the 802.1p tag within the frame. If the frame is untagged the
switch will classify the frame based on the value assigned to the ingress
port.
For tagged frames, you can set the 802.1p frame TCI Threshold which
has a value between 1 and 8. The TCI Threshold will send the tagged
frame into either a high priority queue or low priority queue depending
on the TCI Threshold value. If the value of the frame tag is equal to or less
than the TCI Threshold the frame will be sent to the low priority queue.
For example, if the TCI Threshold is set to 5, incoming frames with a tag
of 6 and above will be sent to the high priority queue. Frames with a tag
of 5 and below will be sent to the low priority queue.
For untagged frames, the port based QoS values that are assigned to
each port determine if the frame is assigned to the high priority queue or
the low priority queue.
You can also set the weights to the high and low priority queues for the
egress of the frames. The priority queue weights have a value between 1
and 15. Weights are designed to allow a set number of outgoing frames
to be delivered from the high priority queue and the low priority queue
based on the high/low ratio. For example, if you have a high priority
queue weight of 15 and low priority queue weight of 1, this means for
every 15 high priority frames sent 1 low priority frame will be sent.
When the QoS is disabled, all tagged and untagged frames are treated
equally and placed in one queue on the switch.
