Overview

The subject of this book, performance evaluation, may be considered as a field of the vast discipline known as teletraffic, whose purpose is to determine rules which optimise the use of the network equipment that handles the traffic requested by users. The book is not therefore strictly concerned with traffic management techniques or equipment optimisation techniques. But, by presenting the techniques used to evaluate performances, we aim to establish the bases for the evaluation of the capacities of traffic handling equipments and for network dimensioning.

The basic function of a telecommunications network is to connect users to other users via their terminals, and to connect users to servers, or terminals to other terminals. The network sets up a connection between two or more terminals by making use of their source and destination addresses.

Behind this very general connection concept are a number of very different realities, bearing in mind the great variety of telecommunications networks, as we will see later. In a "circuit" type network, the term used is connection, a direct relationship established at a physical level. In an "IP" network, the term used is usually session, as there is normally no physical connection (even though the TCP operates in connected mode at the session level). Finally, the terminals connected will not only be fixed subscribers, but also mobile subscribers or servers.

But the fundamental functions remain the same. And throughout this book we will consider only the generic aspects of the world of...