A STUDY OF ISOCHRONOUS CHANNEL REUSE IN DQDB METROPOLITAN-AREA NETWORKS

This paper investigates the isochronous channel reuse problem (ICRP) o n the IEEE 802.6 distributed-queue dual-bus (DQDB) metropolitan area n etwork (MAN). Given a set of established isochronous connections and a set of isochronous connections requests, using a minimal number of is ochronous 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 th at the simplified ICRP (SICRP), in which all of the established isochr onous connections and the isochronous requests are of the same bandwid th, is NP-complete, In this paper we recommend using a tight lower bou nd on the number of required isochronous channels for the SICRP, An ef ficient isochronous channel scheduling algorithm (ICSA), capable of pr oviding a solution close to the lower bound, is also proposed. Simulat ion results indicate that for a limited isochronous bandwidth, the num ber of isochronous connections successfully established by the ICSA is significantly more than that of the isochronous channels allocation s cheme in the DQDB standard.