Analysis of Traffic Access Control Strategies in Integrated Service Networks

A common digital transmission facility provides service to a community of heterogeneous users generating traffic with differing intensity, message length, and bit rate. In order for this type of integrated communication system to handle its traffic demands with high efficiency and flexibility, close control of access and switching at the input node is required. We propose, analyze, and compare two different strategies for managing the access of two types of traffic, a blockable wide-band (WB) type of traffic and a queueable narrow-band (NB) type of traffic, sharing the transmission resource dynamically. The first strategy assigns preemp-tive priority to the WB traffic over the NB traffic, whereas the second strategy employs a wide-band to narrow-band bit rate compression mechanism. Exact analytic models are developed, and solution methods are presented and implemented. It is shown that the best combined performance is obtained when the two strategies are adaptively combined according to the offered load. M I. INTRODUCTION AXIMIZING the traffic handling capacity of a communication facility while satisfying the users' performance requirements has been a common design objective sought by network traffic engineers. In telephone traffic engineering, for instance, most common design models assume that, although individual call requests may differ from one another, they are statistically indistinguishable. Traffic management schemes based on group overflow (alternate routing) [4], trunk reservation [5], etc., have been commonly implemented to maintain maximum useful network throughput. In the future, large integrated service digital networks, ISDN's, are expected to accommodate random demands for bandwidth usage from a population of heterogeneous users. These might include users with integrated multifunction terminals (e.g., telephone, facsimile, videotex sets), generating traffic with differing characteristics and performance requirements. In this paper we consider a bandwidth resource consisting of a (digital) broad-band transmission facility at an access node of such an integrated network. Access requests for