Arbitration ring for accessing a limited bandwidth switching network

摘要

Access to a limited bandwidth switching network of an ATM (Asynchronous Transfer Mode) switch is scheduled using a reservation ring. In general, a limited bandwidth switching network is unable to generate all possible one-to-one input to output channel mappings in a single switch cycle. The limited bandwidth switching network includes one or more routing channels for routing at most B data packets each switch cycle between the input channels and output channels, where the number of data packets B is less than the aggregate output bandwidth that can be directed at the routing channels. Arbitration requests make two passes around the reservation ring each arbitration cycle. Output channel contention is settled during the first pass around the reservation ring. Contention for limited switching network bandwidth is settled during the second pass around the reservation ring. Arbitration requests granted a reservation at the end of an arbitration cycle are issued into the limited bandwidth switching network during a subsequent switch cycle.