Enterprise QoS Solution Reference Network Design Guide

Catalyst 3550—QoS Considerations and Design
2-44
CAT3550(config-if-range)#end
CAT3550#
Catalyst MLS QoS Verification Commands
show mls qos interface buffers
Enterprise QoS Solution Reference Network Design Guide
Chapter 2 Campus QoS Design
Catalyst MLS QoS verification commands for queuing and dropping include the following:
show mls qos interface buffers
show mls qos interface queueing
The show mls qos interface buffers verification command displays the queue sizes (as per-queue buffer
allocation percentages of the total buffer space). Also the command displays if WRED has been enabled
on a queue, and if so, it displays the first and second thresholds (as percentages of the queue’s depth).
In the example below, the queue-limits are set to 5%, 25%, 40%, and 30% of the total queuing buffer
space for Queues 1 through 4 (respectively). Additionally, WRED is enabled on queues 1 through 3 (but
not Q4, as it is the priority queue). The first WRED threshold is set to 5% on Q1 and is set to 80% on
queues 2 and 3.
Example 2-24 Show MLS QoS Interface Buffers Verification for a Catalyst 3550 Switch
CAT3550#show mls qos interface GigabitEthernet0/1 buffers
GigabitEthernet0/1
Notify Q depth:
qid-size
1 – 5 ! Q1 queue-limit is set to 5% of total buffer space
2 – 25 ! Q2 queue-limit is set to 25% of total buffer space
3 – 40 ! Q3 queue-limit is set to 40% of total buffer space
4 – 30 ! Q4 queue-limit is set to 30% of total buffer space
qid WRED thresh1 thresh2
1 ena 40 100 ! WRED is enabled on Q1 – first threshold is set to 40%
2 ena 80 100 ! WRED is enabled on Q2 – first threshold is set to 80%
3 ena 80 100 ! WRED is enabled on Q3 – first threshold is set to 80%
4 dis 100 100 ! WRED is disabled on Q4 (as it is the PQ)
CAT3550#
show mls qos interface queueing
The show mls qos interface queuing verification command displays the CoS-to-Queuing mappings that
have been configured in addition to the bandwidth allocations per queue. On GigabitEthernet interfaces
with WRED enabled, the output also includes the DSCP-to-WRED Threshold mappings. This
information is displayed in a table form, with the first digit of the decimal DSCP value along the Y-Axis
(in rows) and the second digit of the decimal DSCP value along the X-Axis (in columns).
In the example below, the output verifies that the egress expedite queue (priority queue: Q4) is enabled.
Also, the WRR Bandwidth Weights show that, of the remaining bandwidth, Q1 is allocated 5%, Q2 is
allocated 25%, and Q3 is allocated 70%.
Additionally, the DSCP-to-WRED table verifies that Bulk Data (AF11/10), Internetwork Control (DSCP
CS6/48), and Network Control (DSCP CS7/56) are each mapped to the second WRED thresholds (T2)
of their respective queues (as determined by the CoS-to-Queue mappings).
Finally, the CoS-to-Queue map shows that CoS 0 (Best Effort) is assigned to Q2, CoS 1 (Scavenger) has
been assigned to Q1, CoS values 2, 3, 4, 6 and 7 have all been assigned to Q3, and CoS 5 (Voice) has
been assigned to the priority-queue, Q4.
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