A Traffic Scheduling Technique for Metropolitan Area Gateways

In the future, metropolitan area networks (MAN's) will provide high bandwidth interconnection between local access networks in high density office, industrial, and residential settings. In these systems, the metropolitan area gateway (MAG) is responsible for coordinating the flow of traffic in and out of the metropolitan subnetwork. In certain environments, it is expected that the traffic will possess distinct characteristics. In this paper, a technique called SWIFT is proposed which efficiently schedules these traffic flows when the local access network is based upon broadband CATV-type cable technology. SWIFT satisfies the important constraint that it is compatible with existing CSMA/CD packet data network adapters which means that it may be implemented in previously installed systems. In this paper, a throughput model is given for the proposed technique. Also, an analytic model is given which approximates the mean remote delay when the traffic is moderately to heavily remote-bound. The performance results presented indicate that a system operating the SWIFT algorithm can achieve much reduced delays at higher throughput than would otherwise be possible.