Typically, there are two steps to schedule packets in a threestage
bufferless Clos network: 1) To resolve the output port
contention for all the input ports, which is the same problem
as the scheduling in traditional crossbar-based inputqueued
(IQ) switches. 2) To assign the globally conflict-free
paths for the port pairs found in the first step, which is
known as the global path-allocation (GPA).