On Slot Allocation for Time-Constrained Messages in Dual-Bus Networks
IEEE Transactions on Computers
Scheduling Messages with Earliest Deadline Techniques
Real-Time Systems
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The distributed queue dual bus (DQDB) protocol has been jointly adopted by IEEE and ANSI as a standard (IEEE802.6) for metropolitan area networks (MANs). As such, how to provide various services in the DQDB protocol has attracted increasing attention. In particular, how to guarantee the timely delivery of isochronous (real-time) messages with hard deadline constraints is one of the open issues yet to be solved. Previously, we laid a formal basis for allocating pre-arbitrated (PA) slots to isochronous message streams in DQDB networks and devised a slot allocation scheme to statically establish a set of isochronous message streams at system initialization. In this paper, we complement our previous work and propose a dynamic channel setup and tear-down scheme for DQDB networks. The resulting channel establishment and termination procedures are simple, can be easily implemented in DQDB networks, and do not require any changes in the current DQDB standards.