Consolidated Platform Configuration Guide, Cisco Ios Release 15.2(4)E (Catalyst 2960-X Switches - Cisco Catalyst 2960 series Configuration Manual

How to Configure QoS
Command or Action
Step 3
mls qos queue-set output qset-id
buffers allocation1 ... allocation8
Example:
Switch(config)# mls qos
queue-set output 2 buffers 40 20
20 20 10 10 10 10
Step 4 mls qos queue-set output qset-id
threshold queue-id drop-threshold1
drop-threshold2 reserved-threshold
maximum-threshold
Example:
Switch(config)# mls qos
queue-set output 2 threshold 2
40 60 100 200

Consolidated Platform Configuration Guide, Cisco IOS Release 15.2(4)E (Catalyst 2960-X Switches)

620
Purpose
Allocates buffers to a queue set.
By default, all allocation values are equally mapped among the four queues (25,
25, 25, 25). Each queue has 1/4 of the buffer space. When eight egress queues are
configured, then by default 30 percent of the total buffer space is allocated to queue
2 and 10 percent (each) to queues 1,3,4,5,6,7, and 8.
If you enabled 8 egress queues as described in Step 2 above, then the following
applies:
• For qset-id, enter the ID of the queue set. The range is 1 to 2. Each port belongs
to a queue set, which defines all the characteristics of the four egress queues
per port.
• For allocation1 ... allocation8, specify eight percentages, one for each queue
in the queue set. For allocation1, allocation3, and allocation4 to allocation8,
the range is 0 to 99. For allocation2, the range is 1 to 100 (including the CPU
buffer).
Allocate buffers according to the importance of the traffic; for example, give a large
percentage of the buffer to the queue with the highest-priority traffic.
Note To return to the default setting, use the no mls qos queue-set output
qset-id buffers global configuration command.
Configures the WTD thresholds, guarantee the availability of buffers, and configure
the maximum memory allocation for the queue-set (four egress queues per port).
By default, the WTD thresholds for queues 1, 3, and 4 are set to 100 percent. The
thresholds for queue 2 are set to 200 percent. The reserved thresholds for queues
1, 2, 3, and 4 are set to 50 percent. The maximum thresholds for all queues are set
to 400 percent by default.
If you enabled 8 egress queues as described in Step 2 above, then the following
applies:
• For qset-id, enter the ID of the queue-set specified in Step 2. The range is 1
to 2.
• For queue-id, enter the specific queue in the queue set on which the command
is performed. The queue-id range is 1-4 by default and 1-8 when 8 queues
are enabled.
• For drop-threshold1 drop-threshold2, specify the two WTD thresholds
expressed as a percentage of the queue's allocated memory. The range is 1 to
3200 percent.
• For reserved-threshold, enter the amount of memory to be guaranteed
(reserved) for the queue expressed as a percentage of the allocated memory.
The range is 1 to 100 percent.
• For maximum-threshold, enable a queue in the full condition to obtain more
buffers than are reserved for it. This is the maximum memory the queue can
have before the packets are dropped if the common pool is not empty. The
range is 1 to 3200 percent.