Multimedia communication involving digital audio and/or digital video has rather strict delay requirements. A real-time channel is defined in this paper as a simplex connection between a source and a destination characterized by parameters representing the performance requirements of the client. A real-time service is capable of creating real-time channels on demand and guaranteeing their performance. These guarantees often take the form of lower bounds on the bandwidth allocated to a channel and upper hounds on the delays to he experienced by a packet on the channel. In this paper, we study the feasibility of providing real-time services on a packet-switched store-and-forward wide-area network with general topology. We describe a scheme for the establishment of channels with deterministic or statistical delay hounds, and present the results of the simulation experiments we ran to evaluate it. The results are encouraging: our approach satisfies the guarantees even in worst case situations, uses the network's resources to a fair extent, and efficiently handles channels with a variety of offered load and burstiness characteristics. Also, the packet transmission overhead is quite low, and the channel establishment overhead is small enough to be acceptable in most practical cases.

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This article f i s t reviews the architecture of a typical ATM switch and considers the problem of handling both conn'nuous bit oriented and bursty traffic with low loss and delay requirements. We examine six different approaches to handling mixed traffic in an ATM switch, and compare their performance by means of simulation. A switch architemre which distinguishes between three trajjic types with a shared buffer turns out to have the best performance, where by performance we mean the ability of the switch to provide the quality of service (loss and delay ) desired by each application at minimum eqense.