In a network in which logical channels are used and switched for communication services, adaptive bandwidth allocation is possible, and new transfer capabilities handling elastic types of traffic such as ABR traffic have been developed in ATM for the B-ISDN. It should be, however, emphasized that appropriate network operation must be developed in order to support the new services in the most effective way from the viewpoint of both network operators and users. In particular, routing schemes suitable for the elastic traffic are needed for studying and network operation methods must be investigated for the networks in which the stream traffic like CBR and the elastic traffic are supported in a mixed manner. In this paper, we treat an optimal routing problem for the elastic traffic and propose a state dependent routing scheme called CPAR (capacity priority alternate routing). Moreover, an optimal route selection algorithm taking into account the constraints for the routing scheme is presented and a proof of its optimality is provided. It is concluded that CPAR has desirable performance for the elastic class of traffic in cases of partial load increase, in which a route traversing lightly loaded links can be selected with more flexibility and effective load balancing is achieved.

A study is made of various traffic processes associated with Markovian queuing systems, and the moments of the traffic processes are analyzed. The purpose of the study is to develop a means of computing the moments efficiently so as to extend the conventional method of representing the traffic processes to a larger class of queuing systems. As an outcome of the analysis, the recurrence formulae for computing the moments including cross-covariances between multiple traffic processes are derived and expressed in terms of the infinitesimal generator, steady-state probability vector of the Markovian queuing system and a matrix describing traffic rate. The main feature of the analysis is in the utilization of the special block-partitioned structure of the matrices involved. The results are of wide application for the study of various telecommunication networks. Two examples of applications for the Markovian queuing model with batch arrivals and a multislot integrated services system are presented.>