Hierarchical distribution of video with dynamic port allocation

A two-level distribution network for broadcast and interactive video is studied as an example of the hierarchical distribution method. This two-level design has the following advantages: it facilitates switch growth and enhances switch reliability; it reduces the overall circuit mileage of the video distribution system; and video requests can be processed independently by local switches, rendering a large call processor at the central switch unnecessary. A traffic model for this network is formulated and the optimum capacities of the central and local switches are determined for a given blocking requirement. By adding a small crosspoint switch between the two levels, the output ports of the central switch can be dynamically allocated to the local switches. This sharing of output ports can significantly reduce the size of the central switch