Schedule profiles

A schedule profile determines the order in which queues are selected for transmission, and the amount of service available for each queue. A schedule profile must be configured on every interface at all times. A schedule profile can be applied globally to all interfaces, or only to specific interfaces.

Three options are available:

  • All queues use weighted fair queuing (WFQ)
  • All queues use strict priority queuing
  • The highest priority queue uses strict priority, and all other queues use WFQ

A weighted schedule profile assigns relative servicing for each queue. The amount of service per weight is relative to the underlying hardware implementation, and to the weights assigned to the other non-empty queues. Strict scheduling can be used to service queues purely on the basis of highest priority first (at the risk of starving lower-priority queues during high stress periods). A combination of strict and weighted scheduling offers more service to the highest priority queue when needed, while preserving scheduling between the remaining queues, thus decreasing the risk of starvation.

The switch is automatically provisioned with a schedule profile named factory-default, which assigns DWRR to all queues with a weight of 1. Use the command show schedule-profile factory-default to view the default schedule profile. (Do not use show running-configuration, as it only displays changes from the initial settings.)

switch# show qos schedule-profile default
queue_num algorithm weight
--------- --------- ------
0         wfq       1
1         wfq       1
2         wfq       1
3         wfq       1
4         wfq       1
5         wfq       1
6         wfq       1
7         wfq       1