20-60
Catalyst 3550 Multilayer Switch Software Configuration Guide
78-11194-03
Chapter 20 Configuring QoS
QoS Configuration Examples
Step 5
switchport mode trunk
Configure this port as a trunk port.
Step 6
exit
Return to global configuration mode.
Step 7
interface gigabitethernet0/2
Enter interface configuration mode, and specify the ingress interface
connected to the intelligent wiring closet.
Step 8
mls qos trust dscp
Classify incoming packets on this port by using the packet DSCP value.
Step 9
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 is
1 to 2.
•
For dscp1 ... dscp8, specify the DSCP values that are mapped to a
threshold ID. Enter up to eight DSCP values per command. Separate
each value with a space. The DSCP range is 0 to 63.
Step 10
switchport mode trunk
Configure this port as a trunk port.
Step 11
exit
Return to global configuration mode.
Step 12
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
Step 13
interface gigabitethernet0/5
Enter interface configuration mode, and specify the egress interface to
configure.
Step 14
priority-queue out
Enable the expedite queue.
Step 15
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.
Step 16
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