Patent ID: 7843905

Claim:
In a switching node having a plurality of input ports and a plurality of output ports, said switching node having a controller that includes a route-set memory storing a route set of routes for each pair of input and output ports, and a plurality of cascaded schedulers, each scheduler associated with a result memory and schedules connections for a specified sub-set of time slots within a slotted time frame, a method of scheduling connections in response to receiving connection requests, each connection request including a connection descriptor having a connection identifier and specifying one of said plurality of input ports, one of said plurality of output ports and a requested number of time slots in a slotted time frame, said method comprising: determining a number of pending time slots, said number of pending time slots initially equated to said requested number of time slots; selecting a current scheduler, starting with said first scheduler, to allocate allocable time slots and place identifiers of said allocable time slots in said result memory; selecting a subsequent scheduler as said current scheduler; cyclically reading content of said result memory associated with each of said plurality of cascaded schedulers; classifying said routes in each said route set into at least one category such that said allocable time slots may only be allocated within a selected one of said at least one category; sorting said at least one category according to a descending order of preference, a first sorted category being the most preferred; and allowing use of routes in a preferred category for allocating said allocable number time slots; where said pending number of time slots is not zero and said current scheduler is the last of said plurality of cascaded schedulers, repeating said selecting said schedulers allowing use of routes in a next preferred category of said at least one category.