Good net, tune away; bad net, start again from scratch. A dog is a dog.
—Peter J. Schwaller
This chapter explains how to adjust the devices in your network to improve call quality. It discusses quality of service (QoS) and tuning techniques that help make a VoIP deployment successful. It explains what QoS is, when to consider QoS, several different QoS mechanisms and tuning ideas, and how you can configure QoS and make it work. Finally, some practical QoS and tuning recommendations are covered.
The terms QoS and tuning are used in the title of this chapter and in the preceding paragraph. Here is what is meant by these two terms:
QoS— Refers to choices about how different users or different application traffic gets treated on the network. To make changes in your network so that VoIP traffic gets priority over file-transfer traffic, you use QoS techniques.
Tuning— Refers to methods for increasing efficiency or making trade-offs among resources or attributes. For example, if you make a setup change in a device that decreases delay but uses more RAM, you have made a tuning change.
QoS helps to manage competing users, applications, or traffic that is sharing the same network. In the end, it all comes down to the basic human problems of sharing and fairness.
