Cisco Systems 3750E Configuring the Ingress Priority Queue, Mls qos srr-queue input bandwidth

Chapter 36 Configuring QoS

Configuring Standard QoS

Beginning in privileged EXEC mode, follow these steps to allocate bandwidth between the ingress queues. This procedure is optional.

	Command	Purpose
Step 1
	configure terminal	Enter global configuration mode.
Step 2
	mls qos srr-queue input bandwidth	Assign shared round robin weights to the ingress queues.
	weight1 weight2	The default setting for weight1 and weight2 is 4 (1/2 of the bandwidth is
		equally shared between the two queues).
		For weight1 and weight2, the range is 1 to 100. Separate each value with
		a space.
		SRR services the priority queue for its configured weight as specified by
		the bandwidth keyword in the mls qos srr-queue input priority-queue
		queue-idbandwidth weight global configuration command. Then, SRR
		shares the remaining bandwidth with both ingress queues and services
		them as specified by the weights configured with the mls qos srr-queue
		input bandwidth weight1 weight2 global configuration command. For
		more information, see the “Configuring the Ingress Priority Queue”
		section on page 36-72.
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 bandwidth global configuration command.

This example shows how to assign the ingress bandwidth to the queues. Priority queueing is disabled, and the shared bandwidth ratio allocated to queue 1 is 25/(25+75) and to queue 2 is 75/(25+75):

Switch(config)# mls qos srr-queue input priority-queue 2 bandwidth 0

Switch(config)# mls qos srr-queue input bandwidth 25 75

Configuring the Ingress Priority Queue

You should use the priority queue only for traffic that needs to be expedited (for example, voice traffic, which needs minimum delay and jitter).

The priority queue is guaranteed part of the bandwidth to reduce the delay and jitter under heavy network traffic on an oversubscribed ring (when there is more traffic than the backplane can carry, and the queues are full and dropping frames).

SRR services the priority queue for its configured weight as specified by the bandwidth keyword in the mls qos srr-queue input priority-queuequeue-idbandwidth weight global configuration command. Then, SRR shares the remaining bandwidth with both ingress queues and services them as specified by the weights configured with the mls qos srr-queue input bandwidth weight1 weight2 global configuration command.

	Catalyst 3750-E and 3560-E Switch Software Configuration Guide
36-72	OL-9775-02