Abstract
This paper describes several improvements to a nonblocking copy network proposed previously for mtdticast packet switching. Our improvements provide a complete solution to some system problems inherent in mtdticasting. The input fairness problem caused by overtlow is solved by a cyclic running aaVer network (CRAN), which can calculate running sums of copy requests starting from any input port. The starting point can change adaptively in every time slot based on the overflow condition of the previous time slot. The CRAN atso serves as a mtdtieast traffic controller to regulate the overatl copy requests. The throughput of a mtdticast switch ean be improved substantially if partiat service of copy request is implemented when overflow occurs. Call-splitting can also be implemented by the CRAN in a straightforward manner. Nonuniform distribution of replicated packets at outputs of copy network may affect the performance of the following routing network. 'lWs output fairness problem due to undertlow is solved by cyclically shifting the copy packets in every time slot. An approximate queueing model is developed to analyze the performance of tlds improved copy network. It shows that if the loadhtg on each output of the copy network is maintained below 80%, the average packet delay in an input buffer would be less than two time slots.

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