Cisco Gigabit Ethernet Switch Module for HP p-Class BladeSystem Software Configuration Guide

CHAPTER

27-1

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Configuring QoS

This chapter describes how to configure quality of service (QoS) by using automatic QoS (auto-QoS)

commands or by using standard QoS commands on the switch. With QoS, you can provide preferential

treatment to certain types of traffic at the expense of others. Without QoS, the switch offers best-effort

service to each packet, regardless of the packet contents or size. It sends the packets without any

assurance of reliability, delay bounds, or throughput.

You can configure QoS on physical ports and on switch virtual interfaces (SVIs). Other than to apply

policy maps, you configure the QoS settings, such as classification, queueing, and scheduling, the same

way on physical ports and SVIs. When configuring QoS on a physical port, you apply a nonhierarchical

policy map. When configuring QoS on an SVI, you apply a nonhierarchical or a hierarchical policy map.

Note For complete syntax and usage information for the commands used in this chapter, see the command

reference this release.

This chapter consists of these sections:

• Understanding QoS, page 27-1

• Configuring Auto-QoS, page 27-20

• Displaying Auto-QoS Information, page 27-29

• Configuring Standard QoS, page 27-29

• Displaying Standard QoS Information, page 27-75

The switch supports some of the modular QoS CLI (MQC) commands. For more information about the

MQC commands, see the “Modular Quality of Service Command-Line Interface Overview” at this site:

http://www.cisco.com/en/US/products/sw/iosswrel/ps1835/products_configuration_guide_chapter0918

6a00800bd908.html

Understanding QoS

Typically, networks operate on a best-effort delivery basis, which means that all traffic has equal priority

and an equal chance of being delivered in a timely manner. When congestion occurs, all traffic has an

equal chance of being dropped.

When you configure the QoS feature, you can select specific network traffic, prioritize it according to

its relative importance, and use congestion-management and congestion-avoidance techniques to

provide preferential treatment. Implementing QoS in your network makes network performance more

predictable and bandwidth utilization more effective.