TABLE OF CONTENTS In concluding this chapter, we highlight the fact that QOS is not a panacea to all networking ills. There will undoubtedly be cases where, even using QOS mechanisms the SLA requirements cannot be met on a particular network, and hence techniques other than QOS may need to be considered.
Network engineering. In some cases, it may be necessary to re-engineer a network in order to ensure that the SLA requirements of an application can be met. For example, a satellite connection could be replaced by a terrestrial link, in order to reduce the end-to-end delay experienced by an application.
Application engineering. There may be cases where it is more appropriate (cost-effective) to re-engineer an application, or rather re-engineer how an application uses the network such that the applications SLA demands on the network are reduced, than to re-engineer the network to support the original requirements of the application. For example, if the de-jitter buffer on a video end-system is set unnecessarily large it may add unnecessarily to the end-to-end delay, which may increase the channel change time or VoD responsiveness above acceptable thresholds. In this case the right approach to solving the problem is to reduce the de-jitter buffer in the video end-system rather than trying to reduce the network delay. Another example of application engineering is the deployment of distributed application caches throughout the network, which can both reduce the network traffic load due to the application, and also reduce...
