Part Three: Case Studies
The VPLS Case Study
In the previous chapters of this book, the main focus has been the analysis of the QOS tools, one by one, and in Chapter 3 we focused on the challenges of a QOS deployment. We have now introduced all the different parts of the QOS equation and are ready to move forward and present two case studies that illustrate end-to-end QOS deployments in the format of case studies. The case study in this chapter focuses on a VPLS (Virtual Private LAN Service) scenario, and the study in the next chapter examines a mobile network. Using these case studies, we glue together the QOS concepts and tools we have discussed and also explain how to cope with some of the challenges highlighted in Chapter 3. However, as previously discussed, any QOS deployment is never completely independent of other network components, such as the network routing characteristics, because, for example, routing can place constraints on the number of hops, or which particular hops, are crossed by the traffic. So it is not accurate to present a QOS case study without first analyzing the network and its characteristics. However, discussion of the other network components is limited only to what is strictly necessary so that the focus of the case studies always remains on QOS.
This chapter starts by presenting an overview of the network technologies being used and how the particular services are implemented. Then we define the service specifications, starting off with some loose ...