Cisco Systems 3750E Configuring Egress Queue Characteristics, Mls qos srr-queue input, Weight

Chapter 36 Configuring QoS

Configuring Standard QoS

Beginning in privileged EXEC mode, follow these steps to configure the priority queue. This procedure is optional.

	Command	Purpose
Step 1
	configure terminal	Enter global configuration mode.
Step 2
	mls qos srr-queue input	Assign a queue as the priority queue and guarantee bandwidth on the stack
	priority-queue queue-idbandwidth	or internal ring if the ring is congested.
	weight	By default, the priority queue is queue 2, and 10 percent of the bandwidth
		is allocated to it.
		• For queue-id, the range is 1 to 2.
		• For bandwidth weight, assign the bandwidth percentage of the stack
		or internal ring. The range is 0 to 40. The amount of bandwidth that
		can be guaranteed is restricted because a large value affects the entire
		ring and can degrade the switch or stack performance.
Step 3
	end	Return to privileged EXEC mode.
Step 4
	show mls qos interface queueing	Verify your entries.
	or
	show mls qos input-queue
Step 5
	copy running-config startup-config	(Optional) Save your entries in the configuration file.

To return to the default setting, use the no mls qos srr-queue input priority-queuequeue-idglobal configuration command. To disable priority queueing, set the bandwidth weight to 0, for example, mls qos srr-queue input priority-queuequeue-idbandwidth 0.

This example shows how to assign the ingress bandwidths to the queues. Queue 1 is the priority queue with 10 percent of the bandwidth allocated to it. The bandwidth ratios allocated to queues 1 and 2 is 4/(4+4). SRR services queue 1 (the priority queue) first for its configured 10 percent bandwidth. Then SRR equally shares the remaining 90 percent of the bandwidth between queues 1 and 2 by allocating 45 percent to each queue:

Switch(config)# mls qos srr-queue input priority-queue 1 bandwidth 10

Switch(config)# mls qos srr-queue input bandwidth 4 4

Configuring Egress Queue Characteristics

Depending on the complexity of your network and your QoS solution, you might need to perform all of the tasks in the next sections. You will need to make decisions about these characteristics:

•Which packets are mapped by DSCP or CoS value to each queue and threshold ID?

•What drop percentage thresholds apply to the queue-set (four egress queues per port), and how much reserved and maximum memory is needed for the traffic type?

•How much of the fixed buffer space is allocated to the queue-set?

•Does the bandwidth of the port need to be rate limited?

•How often should the egress queues be serviced and which technique (shaped, shared, or both) should be used?

	Catalyst 3750-E and 3560-E Switch Software Configuration Guide
OL-9775-02		36-73