Allied Telesis AlliedWare Plus Overview page 28

Strict priority Then, to set queues to use strict priority scheduling, use the command:
scheduling
Specify the queues as a space-separated list. For example, to put queues 3, 5, and 6 into the
strict-priority group of queues, use the command:
Weighted To put queues into one of the weighted round robin groups, use the command:
round robin
This configures a set of queues in the wrr1 or wrr2 group of queues, and sets their weights in
that group. The weight specifies the number of bytes transmitted from the queue in
proportion to the values for other queues in the same wrr group. For example, a queue with
a weight of 30 would transmit twice as many bytes as a queue with a weight of 15.
To put queues 2 and 7 into the wrr1 group, and give them a weight of 30 in that group, use
the command:
To put queue 5 into the wrr1 group, and give it a weight of 15 in that group, use the
command:
Egress rate It is also possible to set an egress rate limit on a queue, using the command:
limits
You can specify bandwidth in kilobits (e.g. 2000 or 2000k), megabits (e.g. 2m), or gigabits (e.g.
2g).
Although this command begins with the keyword wrr-queue, you can use it to configure
queues that are members of the strict-priority group of queues.
For more information, see
Packet buffer Each port has a dedicated pool of packet buffers that the egress queues use for queuing
pool packets. Theoretically, any one of the queues on a given port could use up that port's whole
buffer pool, although there is a mechanism in place to prevent this. If the mechanism did not
exist, a single queue could use the whole buffer pool, for example, if a port were
oversubscribed by a high-bandwidth high-priority stream and a high-bandwidth low-priority
stream. The high-priority stream would get more access to the egress bandwidth than the
low-priority stream, so the queue holding the low-priority traffic would grow progressively
longer. In the end, the low-priority stream would consume the entire buffer pool on the port,
thereby starving the high-priority stream of any packet-queuing resource. This would be
highly undesirable.
To avoid this problem, there is a limit on the percentage of the available buffer pool that any
given queue can consume. By default, each queue is limited to 12%, but you can change this
by using the following command:
Page 28 | AlliedWare Plus™ OS: Overview of QoS
priority-queue <queue-list>
awplus(config-if)#priority-queue 3 5 6
wrr-queue group <1-2> weight <6-255> queues <queue-list>
wrr-group 1 weight 30 queues
awplus(config-if)#wrr-group 1 weight 15 queues 5
wrr-queue egress-rate-limit <bandwidth> queues <queue-list>
wrr-queue queue-limit <1-100> <1-100> <1-100> <1-100> <1-100> <1-100>
<1-100> <1-100>
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"Egress bandwidth limiting" on page 29.