Overview

Designing an internetwork is just the starting point. To get the best out of it you must systematically fine-tune key areas of the design to improve performance, preserve critical bandwidth, and minimize operating costs. Network optimization is typically performed soon after the network design is complete, and it must be performed periodically throughout the lifetime of the network to ensure that changes in traffic dynamics are monitored and responded to. It is possible to improve even a good network design considerably through judicious configuration, tuning, and the use of specialized software and hardware tools. However, before attempting optimization you should know the baseline characteristics of the network, its systems, and its protocols. Typically, the acceptance stage is the best time to collate baseline data; failing that, you should at least characterize the key systems before attempting to optimize. Without this database you have nothing with which to make comparisons later, and this could lead to wasted time and effort. During the capacity-planning phase you may have also identified potential bottlenecks; again this, may help to focus your attention if performance problems occur [1].

The complex interactions between users, applications, protocols, and systems create dynamic loads on a network that are often hard to predict at the design phase. As networks expand, it becomes all the more important to understand, control, and optimize traffic over the network to preserve valuable bandwidth (and possibly meet service guarantees). This active form of control is often referred to as policy. Traffic engineering policy...