In addition, concepts of network architecture were presented in Chapter 5. 333 334 CHAPTER 8 Performance Architecture If you need additional information on network performance and performance mechanisms, some recommended sources include: • Internet QoS: Architectures and Mechanisms for Quality of Service, by Zheng Wang, Morgan Kaufmann Publishers, March 2001. • Designing Quality of Service Solutions for the Enterprise, by Eric D. Siegel, John Wiley & Sons, October 1999. • HighSpeed Networking: A Systematic Approach to HighBandwidth LowLatency Communication, by James Sterbenz and Joseph Touch, John Wiley & Sons, April 2001. • Queuing Systems Theory, Volume 1, by Leonard Kleinrock, John Wiley & Sons, January 1975. • Requests for Comments from the Differentiated Services (DiffServ) Working Group of the IETF, RFC 2474 and 2475 in particular. See for these RFCs. 8.2 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 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, and the sets of internal and external relationships between this and other component architectures. In this chapter we 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) Developing Goals for Performance 335 Network Devices Controlling Traffic Inputs (AdmissionRates) to the Network Adjusting Baseline Performance (Traffic Engineering) Controlling Network (Prioritization, Scheduling, Traffic Conditioning) Users Net Mgmt Feedback Loops FIGURE 8.1 General Mechanisms for Performance • Support a particular group or groups of users or applications, maybe new or planned applications • Control resource allocation for accounting, billing, and management purposes We 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.