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Configuring QoS
This chapter describes how to configure quality of service (QoS) by using standard QoS commands on
the Catalyst 2928 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 only on physical ports. Configure the QoS settings, such as classification,
queueing, and scheduling, and apply a trusted class of service (CoS) or a CoS override setting.
Note
For complete syntax and usage information for the commands used in this chapter, see the command
reference for this release.
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•
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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.
The QoS implementation is based on the Differentiated Services (Diff-Serv) architecture, an emerging
standard from the Internet Engineering Task Force (IETF). This architecture specifies that each packet
is classified upon entry into the network.
OL-23389-01
Understanding QoS, page 31-1
Configuring Standard QoS, page 31-6
Displaying Standard QoS Information, page 31-17
C H A P T E R
Catalyst 2928 Switch Software Configuration Guide
31
31-1
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Troubleshooting
