Introduction

This chapter outlines some of the more cutting edge QoS mechanisms available at press time. Some of these technologies are just beginning to be widely deployed on production networks, and, though Quality of Service is constantly being improved and modified, these technologies will undoubtedly remain a significant factor in the Quality of Service marketplace for some time to come.

Several of these technologies, such as RSVP and LLQ, are currently being used mostly for voice applications, and you will find that these more advanced mechanisms are often used in conjunction with each other, rather than independently. These mechanisms, although powerful and useful in their own right, gain power and functionality when used along with other mechanisms.

Some of the benefits of more advanced queuing mechanisms are increased granular control of traffic behavior, and the ability to be far more specific when classifying and queuing or dropping traffic. However, this presents a potential problem. There is a trade-off between granular control and flexibility of use. LLQ, for example, is a very specific mechanism with a very specific purpose, but it not well suited for many things other than that purpose. It is particularly important in this chapter to pay attention to recommendations about where the deployment of these technologies is appropriate.

Using the Resource Reservation Protocol (RSVP)

The Resource Reservation Protocol (RSVP) is the first attempt at an industry standard implementation of the Internet Integrated Services (Intserv) model of QoS. Researchers at the Information Sciences Institute (ISI) at the University...