Department of Computer Science

## COM6515 Network Performance Analysis

Summary This module considers the performance of computer networks from a statistical aspect, using queuing theory. It is shown that the performance of a computer network depends heavily on the traffic flow in the network, and different models of traffic and queues are used. These include single-server queues, multiple server queues, and the concept of blocking is discussed. Although the analysis is entirely statistical, all the relevant background is provided in the lectures, such that the course is entirely self-contained. Problem sheets are provided in order to assist the students with the course material. Students should be aware that there are limited places available on this course. Spring 2021/22 15 Formal examination (2 hours) Dr Joab Winkler Introduce a statistical analysis of computer networks Show how queuing theory can be used to analyse computer networks Show the applications of queuing theory to other areas of science and engineering By the end of the unit the candidate should be able to: Analyse queuing networks and their application to computer networks Show how to design a computer network so that the queues are within specified bounds Appreciate the importance of queuing theory to other areas of engineering Review material: Networking Introduction. Random processes and probability theory. The Poisson distribution A simple network queue: M/M/1 queue Birth death processes Little's formula Richer queueing models: M/M/M/1. Queues in which the arrival and service rates are functions of the state system Queues with blocking Erlang delay. Erlang loss system. Erlang B and C curves. M/G/1. Overview of Simulation: Sampling theory. Obtaining samples from Markov chains. The course requires basic probability theory and knowledge of arithmetic and geometric progressions. This knowledge is basic and it is covered in all undergraduate engineering and physics degrees. The teaching method is by lectures with numerous example and problem sheets so that the students have a good theoretical and practical understanding of the subject. 30 Hours of formal lectures, which includes problem classes. Problem sheets are are set and discussed in class and this provides an opportunity for feedback. Core Text: Data Networks (Second Edition) by Dimitri Bertsekas and Robert Gallager Background : Computer Networks by Andrew S. Tanenbaum