Allied Telesis AT-S79 manual AT-GS950 Series, Ieee 802.1p Traffic Class

AT-S79 Management Software User’s Guide

Table 2. Default Mappings of IEEE 802.1p Priority Levels

to Egress Port Priority Queues

	AT-GS950 Series
IEEE 802.1p Traffic Class	Egress Port Priority
	Queue
0	0
1	0
2	0
3	1
4	2
5	2
6	3
7	3

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-S79 management software. The procedure for changing the default mappings is found in “Mapping CoS Priorities to Egress Queues” on page 99. 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 completely ignore the priority levels in its tagged packets and instead use a temporary priority level assigned to the port. For instance, perhaps you decide that all tagged packets received on 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 102.

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 102.

Section I: Using the Menus Interface 97