Scheduling with relaxed constraint for ATM-like input-queued crossbar switching fabric in IP router

A scheduling scheme for ATM-like input-queued crossbar switching fabric in the IP router performs a critical role in the IP router. However, there is a problem among the existing scheduling schemes: when an IP router with a large number of outputs (e.g. 64, 128 or more) is connected to only a few nodes (e.g. 2 or 4 nodes, where the node may be another IP router or a switch), the switching capability is not fully utilized. We propose an approach to improve the existing scheduling schemes: all outputs of the switching fabric are divided into a few groups whose number is equal to the number of nodes to be connected, and outputs in the same group are multiplexed into a high-speed output link which is connected to a node. Therefore all outputs of the switching fabric can join the switching. The approach is applied to several popularly used scheduling algorithms. Simulation is carried out to demonstrate a better performance.