QOS-Enabled Networks, 2nd Edition

9The 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 three case studies that illustrate end-to-end QOS deployments in the format of case studies. The case study in this chapter focuses on a Virtual Private LAN Service (VPLS) scenario, the second one is focused in the internals of a Data Center, and the third one in a mobile network. The reason for selecting these three realms is due to the fact that they are the most challenging ones at present, but unquestionably the lessons learned from it can be translated to other less complex realms, like an enterprise deployment by just removing the MPLS component out of the equation of this case study. 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 ...