Management and Configuration Guide K/KA/KB.15.15

• Queue 5 (medium priority): 10%
• Queue 6 (medium priority): 10%
• Queue 7 (high priority): 15%
• Queue 8 (high priority): 20%
The no form of the command disables GMB for all ports in the port-list. In this state, which is
the equivalent of setting all outbound queues on a port to 0 (zero), a high level of higher-priority
traffic can starve lower-priority queues, which can slow or halt lower-priority traffic in the network.
You can configure bandwidth minimums from either the global configuration level (as shown above)
or from the port context level.
Syntax
[no] int <port-list> bandwidth-min output [ 0-100 | strict ]
[0-100]
Select a minimum bandwidth.
For ports in port-list, specifies the minimum outbound bandwidth as a percent of the total
bandwidth for each outbound queue. The queues receive service in descending order of priority.
You must specify a bandwidth percent value for all except the highest priority queue, which may
instead be set to "strict" mode. The sum of the bandwidth percentages below the top queue cannot
exceed 100%. ( 0 is a value for a queue percentage setting.)
Configuring a total of less than 100% across the eight queues results in unallocated bandwidth
that remains harmlessly unused unless a given queue becomes oversubscribed. In this case, the
unallocated bandwidth is apportioned to oversubscribed queues in descending order of priority.
For example, if you configure a minimum of 10% for queues 1 to 7 and 0% for queue 8, the
unallocated bandwidth is available to all eight queues in the following prioritized order:
Queue 8 (high priority)
Queue 7 (high priority)
Queue 6 (medium priority)
Queue 5 (medium priority)
Queue 4 (normal priority)
Queue 3 (normal priority)
Queue 2 (low priority)
Queue 1 (low priority)
A setting of 0 (zero percent) on a queue means that no bandwidth minimum is specifically reserved
for that queue for each of the ports in the port-list.
Also, there is no benefit to setting the high-priority queue (queue 8) to 0 (zero) unless you want the
medium queue (queue 4) to be able to support traffic bursts above its guaranteed minimum.
[strict]
Provides the ability to configure the highest priority queue as strict. Per-queue values must be
specified in priority order, with queue 1 having the lowest priority and queue 8 (or 4, or 2) having
the highest priority (the highest queue is determined by how many queues are configured on the
switch. Two, four, and eight queues are permitted. (See the qos queue-config command.)
The strict queue is provided all the bandwidth it needs. Any remaining bandwidth is shared among
the non-strict queues based on need and configured bandwidth profiles (the profiles are applied
to the leftover bandwidth in this case.) The total sum of percentages for non-strict queues must not
exceed 100.
178 Port Traffic Controls