Chapter 7
Models of Links Carrying Multi-Service Traffic
7.1 Introduction
The calculation procedure for a determination of the traffic characteristics of networks servicing multi-service traffic streams, such as integrated services digital networks (ISDN), is a complex issue [1–5]. Multi-service traffic is a mixture of different classes of multi-rate traffic, each of which demands a certain number of channels to service its own call. In stochastic analysis of network systems that are offered multi-service traffic streams it is thus necessary to take into consideration the class of a call and the number of channels required to service the call. This, in consequence, leads to a complex description of service processes in network systems to which such call streams are offered.
The situation is even more complicated in the case of a description of broadband multi-service network systems [1, 5–7] that service not only constant bit rate (CBR) traffic sources, but also variable bit rate (VBR) traffic sources. These sources require a bigger number of parameters to describe traffic streams. Therefore, in order to simplify the description of broadband networks — in which virtual circuit switching is used either partly (as in IP networks) or entirely (as in asynchronous transport mode (ATM) networks) — a notion of the so-called equivalent bandwith [7, 8] has been introduced for those traffic classes that are characterized by variable bit rate. Equivalent bandwidths are certain constant bit ...
