A new scheme for dynamic management of isochronous channels in integrated rings

Abstract

The present papers proposes a new scheme that allows dynamic maintenance, allocation and release of the isochronous bandwidth in hybrid rings. The main properties of the new scheme are: (1) it permits the stations to bundle together several low-speed isochronous channels to form one high-speed channel; (2) the acquiring of isochronous channels by ring stations, as well as their release, are cheap, fast and simple processes, since thereis no need to communicate with other stations for this purpose; (3) the acquiring and release processes are decentralized; (4) the overhead bandwidth required by the scheme is very small; (5) the allocation rate is not affected by the number of stations in the ring or by the number of stations that require isochronous channels at the same time. The main principle behind the new scheme is to divide the isochronous bandwidth into fixed length slots, and to maintain the available channels in each slot as a linked list. Since the linked-lists use only octets of available channels, the required overhead is negligible. The paper presents also a mechanism for recovery from transmission errors that may disrupt the linked-lists and interfere with the proper operation of the new scheme. The main concepts of the paper are applicable to the FDDI-II networks. © 1992.