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Catalyst 3750-X and 3560-X Switch Software Configuration Guide
OL-21521-01
Chapter 39 Configuring QoS
Configuring Standard QoS
Beginning in privileged EXEC mode, follow these steps to configure the memory allocation and to drop
thresholds for a queue-set. This procedure is optional.
Command Purpose
Step 1
configure terminal Enter global configuration mode.
Step 2
mls qos queue-set output qset-id
buffers allocation1 ... allocation4
Allocate buffers to a queue-set.
By default, all allocation values are equall
y mapped among the four
queues (25, 25, 25, 25). Each queue has 1/4 of the buffer space.
• 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 ... allocation4, specify four percentages, one for each
queue in the queue-set. For allocation1, allocation3, and allocation4,
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 traf
fic; for example,
give a large percentage of the buffer to the queue with the highest-priority
traffic.
Step 3
mls qos queue-set output qset-id
threshold queue-id drop-threshold1
drop-threshold2 reserved-threshold
maximum-threshold
Configure the WTD thresholds, guarantee the availability of buffers, and
co
nfigure 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
percen
t. 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.
• 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 range is 1 to 4.
• 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.
Step 4
interface interface-id Specify the port of the outbound traffic, and enter interface configuration
mode.
Step 5
queue-set qset-id Map the port to a queue-set.
For qset-i
d, enter the ID of the queue-set specified in Step 2. The range is
1 to 2. The default is 1.
Step 6
end Return to privileged EXEC mode.
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