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Catalyst 3550 Multilayer Switch Software Configuration Guide
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Chapter20 Co nf iguring QoS
QoS Configuration Examples
Step5 switchport mode trunk Configure this port as a trunk port.
Step6 exit Return to global configuration mode.
Step7 interface gigabitethernet0/2 Enter interface configuration mode, and specify the ingress interface
connected to the intelligent wiring closet.
Step8 mls qos trust dscp Classify incoming packets on this port by using the packet DSCP value.
Step9 wrr-queue dscp-map threshold-id
dscp1 ... dscp8 Map the ingress DSCP values to the WRED thresholds of the egress
queues.
In the default DSCP-to-threshold map, all DSCP values are mapped to
threshold 1.
•For threshold-id, specify the threshold ID of the queue. The range i s
1 to 2.
•For dscp1 ... dscp8, specify the DSCP values that are mapped to a
threshold ID. Enter up to eight DSCP values per c om ma nd. Separate
each value with a space. The DSCP range is 0 to 63.
Step10 switchport mode trunk Configure this port as a trunk port.
Step11 exit Return to global configuration mode.
Step12 mls qos map dscp-cos dscp-list to cos Modify the DSCP-to-CoS map. You can enter up to eight DSCP values
separated by spaces in the DSCP-to-CoS map.
For example, to map DSCP values 57 to 63 to CoS 5, enter:
mls qos map dscp-cos 57 58 59 60 61 62 63 to 5
Step13 interface gigabitethernet0/5 Enter interface configuration mode, and specify the egress interface to
configure.
Step14 priority-queue out Enable the expedite queue.
Step15 wrr-queue bandwidth weight1 weight2
weight3 weight4 Configure WRR weights to the egress queues to determine the ratio of the
frequency at which packets are dropped. Separate each value with a space.
The weight range is 0 to 65536.
In this example, to configure the weights so that queue 4 is serviced more
frequently than the other queues, enter:
wrr-queue bandwidth 1 2 3 4
Because the expedite queue is enabled, only the first three weights are
used in the ratio calculation.
Step16 wrr-queue random-detect
max-threshold queue-id
threshold-percentage1
threshold-percentage2
Enable WRED and assign two WRED threshold values to an egress queue
of a Gigabit-capable Ethernet port.
•For queue-id, the range is 1 to 4.
•For threshold-percentage1 threshold-percentage2, the range is 1 to
100 percent.
In this example, to configure the thresholds, enter:
wrr-queue random-detect max-threshold 1 20 100
wrr-queue random-detect max-threshold 2 40 100
wrr-queue random-detect max-threshold 3 60 100
wrr-queue random-detect max-threshold 4 80 100
Command Purpose