User Guide

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Catalyst 6500 Series Switch Cisco IOS Software Configuration Guide—Release 12.1 E
78-14099-04
Chapter 31 Configuring PFC QoS
Configuring PFC QoS
Allocating Bandwidth Between LAN-Port Transmit Queues
The switch transmits frames from one standard queue at a time using a WRR algorithm. WRR uses the
ratio between queue weight values to decide how much to transmit from one queue before switching to
the other. The more the ratio favors a queue, the more transmit bandwidth is allocated to it.
To allocate bandwidth for an egress LAN port, perform this task:
This example shows how to allocate a 3-to-1 bandwidth ratio for Gigabit Ethernet port 1/2:
Router# configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
Router(config)# interface gigabitethernet 1/2
Router(config-if)# wrr-queue bandwidth 3 1
Router(config-if)# end
Router#
This example shows how to verify the configuration:
Router# show queueing interface gigabitethernet 1/2 | include bandwidth
WRR bandwidth ratios: 3[queue 1] 1[queue 2]
Router#
Setting the Receive-Queue Size Ratio on a 1p1q0t or 1p1q8t Ingress LAN Ports
To set the size ratio between the strict-priority and standard receive queues on a 1p1q0t or 1p1q8t
ingress LAN ports, perform this task:
Command Purpose
Step 1
Router(config)# interface type
1
slot/port
1. type = ethernet, fastethernet, gigabitethernet, or tengigabitethernet
Selects the interface to configure.
Step 2
Router(config-if)# wrr-queue bandwidth
low_priority_queue_weight
[medium_priority_queue_weight]
high_priority_queue_weight
Allocates bandwidth between standard transmit queues.
The valid values for weight range from 1 to 255.
Router(config-if)# no wrr-queue bandwidth
Reverts to the default bandwidth allocation.
Step 3
Router(config-if)# end
Exits configuration mode.
Step 4
Router# show queueing interface type
1
slot/port
Verifies the configuration.
Command Purpose
Step 1
Router(config)# interface {fastethernet |
tengigabitethernet} slot/port
Selects the interface to configure.
Step 2
Router(config-if)# rcv-queue queue-limit
standard_queue_weight
strict_priority_queue_weight
Sets the size ratio between the strict-priority and standard
receive queues.
Router(config-if)# no rcv-queue queue-limit
Reverts to the default the size ratio.
Step 3
Router(config-if)# end
Exits configuration mode.
Step 4
Router# show queueing interface {fastethernet |
tengigabitethernet} slot/port
Verifies the configuration.