A study of isochronous channel reuse in DQDB metropolitan area networks

This paper investigates the isochronous channel reuse problem (ICRP) on the IEEE 802.6 distributed-queue dual-bus (DQDB) metropolitan area network (MAN). Given a set of established isochronous connections and a set of isochronous connections requests, using a minimal number of isochronous bandwidth to service all of the connections is attempted. On the other hand, given a limited isochronous bandwidth, establishing a maximal number of isochronous connections is of primary concern. Our previous study demonstrates that the ICRP is NP-complete by showing that the simplified ICRP (SICRP), in which all of the established isochronous connections and the isochronous requests are of the same bandwidth, is NP-complete. We recommend using a tight lower bound on the number of required isochronous channels for the SICRP. An efficient isochronous channel scheduling algorithm (ICSA), capable of providing a solution close to the lower bound, is also proposed. Simulation results indicate that for a limited isochronous bandwidth, the number of isochronous connections successfully established by the ICSA is significantly more than that of the isochronous channels allocation scheme in the DQDB standard