A Markov Service Policy with Application to the Queueing Study of a DQDB Station

In this paper, a queueing system is formulated, analyzed and applied for the study of the queueing behavior of a DQDB station. At rst, an appropriate process is deened to capture the station's perception of the state of the distributed global queue (DQDB network) and a queueing model is formulated. In the sequel, a general queueing system is considered; the packet service time requirement is assumed to depend on the state of an underlying Markov chain at the time when the packet is forwarded to the head of the queue. Finally, the process which captures the state of the global distributed queue is approximated and the resulting queueing model for the DQDB station is related to the general queueing system and analyzed. Results for the queue occupancy distribution of the DQDB station are derived and compared with simulations. The Distributed Queue Dual Bus (DQDB) medium access protocol has been adopted as a Metropolitan Area Network (MAN) Standard (IEEE 802.6), 1]. It is a simple protocol which can achieve full utilization of the channel capacity. The DQDB MAN is a high speed (over 100 Mbps) integrated services network designed to accommodate traac generated by a variety of information sources, as well as provide for the interconnection of LANs. A detailed description of the Distributed Queue Dual Bus (DQDB) protocol may be found in 1]. A brief discussion on the protocol, as well as on various design and performance analysis issues, may be found in 2]-8] and the references cited there. No bandwidth balancing mechanism or priorities are investigated in the DQDB application considered in this paper, 1, 3, 7]. In this paper a single server queueing system is developed, analyzed and applied for the evaluation of the queueing behavior of a tagged DQDB station. Although the DQDB application has motivated the study of this queueing system, its generality allows for potentially wide applicability. Due to the distributed nature of the DQDB protocol, the service provided to a tagged station depends on the station's perception of the state of the global distributed queue which models the entire network. An appropriate process, which is capable of describing the station's perception of the state of the global queue at time instants of interest is identiied (balance process). The service discipline at the local queue of the tagged DQDB station is then described in terms of the balance process; the state of the process at …