Allied Telesis AT-S101 User Manual

Page 63

AT-S101 Management Software User’s Guide

For example, a tagged packet with a priority tag of 6 is placed in the
egress port’s highest priority queue of 3, while a packet with a priority tag
of 1 is placed in the lowest priority queue.

Note

QoS is disabled by default on the switch.

You can customize these priority-to-queue assignments using the
AT-S101 Management Software. The procedure for changing the default
mappings is found in “Mapping CoS Priorities to Egress Queues” on
page 65. Note that because all ports must use the same priority-to-egress
queue mappings, these mappings are applied at the switch level. They
cannot be set on a per-port basis.

You can configure a port to ignore the priority levels in its tagged packets
and use a temporary priority level assigned to the port instead. For
instance, perhaps you decide that all tagged packets received by port 4
should be assigned a priority level of 5, regardless of the priority level in
the packets themselves. The procedure for overriding priority levels is
explained in “Configuring CoS” on page 67.

CoS relates primarily to tagged packets rather than untagged packets
because untagged packets do not contain a priority level. By default, all
untagged packets are placed in a port’s Q0 egress queue, the queue with
the lowest priority. But you can override this and instruct a port’s untagged
frames to be stored in a higher priority queue. The procedure for this is
also explained in “Configuring CoS” on page 67.

Table 1. Default Mappings of IEEE 802.1p Priority Levels

to Egress Port Priority Queues

IEEE 802.1p Traffic Class

AT-GS950/8POE

Egress Port Priority

Queue