A hierarchical scheme for combined access control and routing of circuit-switched traffic in ISDN environments

For integrated networks that support circuit-switched traffic classes with varying bandwidth requirements, an efficient integration of the access control and routing functions is important in realizing optimum network performance. A hierarchical scheme for combined access control and routing is presented for realizing the above objective. The hierarchy comprises two levels; at the lower level each network node implements a distributed call routing strategy, while at the higher level a network supervisor implements an access control policy for minimizing the overall blocking probability. The access control problem to be solved at the supervisor level is formulated in an integer programming framework by a partitioning approach which divides the overall network into several distinct subnets, one corresponding to each bandwidth class. For routing the admitted calls within each subnet in an optimal fashion, a distributed minimum loss routing scheme is developed for implementation at the network nodes. Performance evaluation studies showing the superiority of the various control functions developed are presented