A DYNAMIC BANDWIDTH-ALLOCATION-BASED PRIORITY MECHANISM FOR THE PI-PERSISTENT PROTOCOL FOR MANS

While a variety of medium access protocols have been proposed recently for Metropolitan Area Networks (MAN's), the problem of handling multi priority traffic effectively in these networks remains open. We presen t a simple and effective priority mechanism for an existing MAN protoc ol known as the p(i)-persistent protocol, a probabilistic scheduling s cheme which has been shown to be suitable for applications requiring l arge bandwidth over long, repeater-free distances. Our mechanism works by clipping the low-priority stations in a controlled manner, and the reby increasing the bandwidth available to the high-priority stations. This mechanism operates entirely within the framework of the basic p( i)-persistent protocol, and may be easily tailored to achieve specific performance goals by selection of a single operating parameter. In ad dition, we present a multipriority version of a distributed algorithm by which the stations can update their operating parameters and adapt to changing network conditions dynamically.