Chapter 9. Quality of Service

Terms you'll need to understand:

• Quality of Service (QoS)

• Delay, jitter, and packet loss

• Packetization, serialization, and propagation

• Classification, marking, and queuing

• Weighed random early detection

• Custom, priority, weighted fair, and low latency queuing

Techniques you'll need to master:

• Understanding issues with IP telephony

• Understanding QoS issues and prioritization

• Understanding the similarities and differences between the various queuing methods

• Configuring modular QoS CLI and queuing solutions

In network environments that have voice, video, and data, quality of service (QoS) becomes an important issue. Certain applications, especially voice and video, need to have a necessary infrastructure to support their needs. For instance, if not enough bandwidth is given to these applications, or if too much delay or jitter occurs, voice and video quality suffers. QoS provides solutions to these problems. QoS solutions can be something as complex as providing end-to-end guarantees for a connection or something as simple as prioritizing traffic through queuing. This chapter starts off by discussing IP telephony and some of its issues and solutions, and then delves into QoS in more depth, discussing QoS components and architecture of QoS, and the configuration of various QoS solutions.