Administrator Guide

Layer 2 Switching Commands 680
Command Mode
Global Configuration mode or Interface Configuration (gigabitethernet,
port-channel, tengigabitethernet, fortygigabitethernet) mode
User Guidelines
This command changes the scheduling policy for packet transmission of the
selected CoS queues. It does not change the packet buffering policy nor does
it reserve packet buffers to a CoS queue.
The maximum number of queues supported per interface is seven. It is
recommended that the operator avoid the use of queue 5-7 to avoid conflicts
with inter- and intra-network control traffic.
In order to better accommodate bursty traffic, it is recommended that the
sum of the configured min-bandwidths be much less than 100%. Configuring
the minimum bandwidths such that they sum to 100% effectively locks the
scheduler such that bandwidth sharing by lower priority queues cannot be
accommodated under congestion conditions.
When ETS is operational on an N4000 series switch, this command overrides
the ETS assignments and assigns minimum bandwidth constraints across
traffic class groups. This allows the administrator to ensure that the frame
scheduler does not completely starve lower priority groups when strict priority
is enabled on a high numbered TCG. Specifically, assigning a minimum
bandwidth to a lower numbered TCG, even when strict priority is enabled on
a higher numbered TCG, will alter the normal scheduler behavior and cause
the scheduler to process frames from the lower numbered TCG to conform to
the min-bandwidth constraint.
Example
The following example displays how to specify the minimum transmission
bandwidth guarantee for cos-queues 0 through 6 as follows:
Cos Queue 0—5% scheduler capacity
CoS Queue 1—5% scheduler capacity
CoS Queue 2—10% scheduler capacity
CoS Queue 3—10% scheduler capacity
CoS Queue 4-7—Shared scheduler capacity.
console(config)#cos-queue min-bandwidth 5 5 10 10 0 0 0