2 - Capacity Planning

Abstract

Capacity planning primarily deals with understanding and quantifying user response times, application behavior, performance characteristics, and network utilization. This chapter covers the penalties of poor or non-existent capacity planning that are likely to be financially disastrous on any medium to large network. The key to successful network capacity planning is to understand the needs of the users and behavior of networked applications and services. Capacity planning lays the foundations of the design phase; if the foundations are bad, then cracks begin to appear in the design, and the costs of repair starts to spiral. In order to perform useful modeling and produce an effective design, it is important that the initial traffic assumptions and estimates that are made be meaningful and have some resemblance to what is likely to happen on the network. As these data are used to predict future expansion, it is very important that these data are a reasonable reflection of reality. In designing a new network, a considerable amount of theoretical and empirical test data needs to be gathered, checked, and analyzed. Close attention is required for accurate capacity plans for network traffic, host utilization, and application performance. Moreover, these plans need to be updated religiously and then scrutinized to see if they affect design. This chapter addresses these issues by outlining a capacity management framework.