Wavefront arbiter

A Wavefront arbiter is a circuit used to make decisions which control the crossbar of a high capacity switch fabric in parallel. It was commercialized in the TT1 and TTx chip sets designed by Abrizio and sold by PMC-Sierra.

A crossbar is the central portion of a crossbar switch fabric which connects the inputs to the outputs. A set of decisions of which inputs are connected to which outputs must be made each arbitration period. In high speed cell switching or packet switching applications, the arbitration period is very short. There are often millions or billions of arbitration periods per second.

An arbiter is the circuit that makes the decision as to which of the crossbar's many switches should be closed. Speed is a key design criterion of an arbiter in some applications.

A wavefront arbiter is a particular type of arbiter that is optimized for high-speed operation. For a unicast switch, the algorithm is as follows:

The benefits of this type of calculation include:

There are numerous variants of this method including:

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