Chapter 1. QoS Overview

This chapter covers the following exam topics specific to the QoS exam:

QoS Exam Topics

• Given a description of a converged network, identify problems that could lead to poor quality of service, and explain how the problems might be resolved

• Define the term Quality of Service (QoS) and identify and explain the key steps to implementing QoS on a converged network

• Explain the QoS requirements of the different application types

Cisco provides a large number of quality of service (QoS) features inside Cisco IOS Software. When most of us think about QoS, we immediately think of the various queuing mechanisms, such as Weighted Fair Queuing, or Custom Queuing. QoS features include many more categories, howeverfragmentation and interleaving features, compression, policing and shaping, selective packet-drop features, and a few others. And inside each of these categories of different QoS tools, there are several competing optionseach with varying degrees of similarities both in concept and configuration.

To remember all the details about QoS tools, you need a firm foundation in the core concepts of QoS. This chapter, as well as Chapter 2, "QoS Tools and Architectures," provides the foundation that you need to organize the concepts and memorize the details in other chapters.