Today’s high-capacity communication channels based on fiber optics have resolved at least one of the big communication problems, point-to-point capacity. Now the next problem, switching, must be tackled.

Leung and Yum discuss a proposal for a video distribution system based on a high-speed switch discussed in a previous paper [1]. This paper describes a modular architecture for distributing both broadcast and switched video and presents design algorithms for establishing multirate point-to-point and point-to-multipoint connections.

The authors claim that this architecture has three advantages: it can accommodate multirate video transmission; the video can be broadcast or multicast; and the architecture can be used as a building block for constructing large video distribution systems.

The components consist of a video adapter, video switch, slot assignment processor, and a set of output adapters, all of which are described in detail. It is said that in comparison with other schemes, such as those used in asynchronous transfer mode (ATM), this system can eliminate the overhead of guaranteeing the channel delay and controlling the packet loss rate, and the need for regulating the input rate of each session.

The authors present algorithms for evaluating the slot assignment for point-to-point transmissions and for point-to-multipoint transmissions. An example of a video network providing services to a large bank of customers using the components is presented. Blocking probabilities and time complexities are given.

The paper is well written, shows a good knowledge of the technical problems involved, and is quite short, given the nature of the subject. Engineers involved in the design of switches or high-speed or video transmission networks would profit from reading it.