METHOD AND APPARATUS FOR SUPPLYING REQUESTS TO A SCHEDULER IN AN INPUT-BUFFERED MULTIPORT SWITCH

摘要

A method and apparatus for supplying new requests to a scheduler in an input-buffered multiport switch involve selecting a request that does not target output channels that conflict with output channels targeted by requests that are already accessible to the scheduler. Specifically, target output channels of requests that are presently accessible to the scheduler are identified and compared to target output channels of requests that are included in a queue of next-in-line requests. The queue of next-in-line requests is reviewed and the highest priority request having no conflicting output channels is supplied to the scheduler. By supplying the scheduler with a new request that targets non-conflicting output channels, the scheduler is presented with a wider range of requested output channels from which to choose in each arbitration cycle. In a first embodiment, one, two, or eight ports are connected to each one of four input/output controllers in a switch having a four-channel switch fabric. To supply the scheduler with new requests, secondary arbitration is performed on a channel-specific basis in order to supply channel-specific requests to the scheduler. The method of supplying requests to the scheduler can be scaled to include multiple channels and multiple packet priority designations.