Method and apparatus for scheduling cells in an input-queued switch

摘要

A high-bandwidth input-queued switch includes a set of input queues, a rotating priority iterative matching desynchronizing scheduler, and a crossbar switch. Each input queue includes at least one stored cell with an output device designation signal and a data signal. Each output device designation signal is processed by the rotating priority iterative matching desynchronizing scheduler so that the data signal associated with the output device designation signal is routed through the crossbar switch to an output device specified by the output device designation signal. The rotating priority iterative matching desynchronizing scheduler includes a set of grant scheduler units, each of which receives a set of device designation signals and generates an input device grant signal on the basis of a grant scheduler priority designation signal. The scheduler also includes a set of accept scheduling units, each of which receives a set of input device grant signals from the grant scheduling units, and generates a input/output match signal on the basis of an accept scheduler priority designation signal. Each grant scheduling unit includes a grant scheduler register that stores the grant scheduler priority designation signal. The grant scheduler priority designation signal is incremented when an input device grant signal results in an input/output match signal at one of the accept scheduler units. Each accept scheduler unit includes an accept scheduler register that stores the accept scheduler priority designation signal. The accept scheduler priority designation signal is incremented when the input/output match signal is selected.