PACCI: a high-performance MAC protocol for client-server-based gigabit LANs and MANs

Presents an assessment of several existing medium access control (MAC) protocols in terms of four criteria: cyclicity/cycle gap, access mode, delay invulnerability, and prioritized access. From these protocols, we selected the adaptive cycle cell insertion (ACCI) mechanism as showing the most promise of satisfying these criteria and modeled our proposed prioritized ACCI (PACCI) protocol on its more desirable features. PACCI is suitable for client-server-based gigabit LANs and MANs. It provides fair access for regular nodes by means of regular cycles, and offers prioritized access to privileged nodes by means of restricted cycles. PACCI´s bandwidth allocation for the regular and restricted cycles is then based on an analytic model in an attempt to guarantee QoS by maintaining throughput under diverse traffic loads. Our analysis considered throughput as a function of the restricted cycle/regular cycle ratio (RS/RG) and showed that as RS/RG grows, the throughput difference between privileged and regular nodes increases. Simulation results confirmed the accuracy of the analysis. We also found that the throughput and end-to-end delay are not dependent on the cycle ratio under light load conditions, but that as the network load increases, the benefit of having restricted cycles becomes evident. Simulation results also showed that PACCI assures minimal delay for privileged nodes while incurring reasonable performance degradation for regular nodes