8.3 Background

Performance is the set of levels for capacity, delay, and RMA in a network. It is usually desirable to optimize these levels, either for all (user, application, and device) traffic flows in the network or for one or more sets of traffic flows, based on groups of users, applications, and/or devices.

In support of performance in the network, a performance architecture is the set of performance mechanisms to configure, operate, manage, provision, and account for resources in the network that support traffic flows. The performance architecture shows where these mechanisms are applied within the network, as well as the sets of internal and external relationships between this and other component architectures. In this chapter, we will learn about network resources and about mechanisms to control and manage them.

An important part of developing this architecture is determining the performance goals for your network. For example, performance may be applied to:

Improve the overall performance of the network (e.g., to improve response times and throughput to all users, regardless of where they are and what they are doing)
Support a particular group or groups of users or applications, may be new or planned applications
Control resource allocation for accounting, billing, and/or management purposes

We will discuss developing goals for performance later in the next section. In general, performance consists of one or more of the following: controlling traffic inputs to the network (admission and rate controls); adjusting the baseline performance of the network (traffic or capacity engineering); controlling all or part of the network for delivery of specific services (prioritizing, scheduling, and conditioning traffic flows); and implementing a feedback loop to users, applications, devices, and management to modify controls as necessary. Figure 8.1 shows these general mechanisms.

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Figure 8.1: General mechanisms for performance.