CHAPTER
29-1
Catalyst 2960 Switch SoftwareConfiguration Guide
78-16881-01
29
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 Catalyst 2960 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. Other than to apply policy maps, you configure the QoS
settings, such as classification, queueing, and scheduling, the same way on physical ports. When
configuring QoS on a physical port, you apply a 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 29-1
Configuring Auto-QoS, page 29-19
Displaying Auto-QoS Information, page 29-28
Configuring Standard QoS, page 29-28
Displaying Standard QoS Information, page 29-69
The switch supports some of the modular QoS CLI (MQC) commands. For m ore information about the
MQC commands, see the “Modular Quality of Service Command-Line Interface Overview” at this site:
http://www.cisco.com/univercd/cc/td/doc/product/software/ios122/122cgcr/fqos_c/fqcprt8/
qcfmdcli.htm#89799

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 conge stion-avoidance techniques to
provide preferential treatment. Implementing QoS in your network makes network performance more
predictable and bandwidth utilization more effective.