Patent ID: 8553683

Claim:
A method for operating an intra-domain switch in a first set of intra-domain switches in a non-blocking switch fabric having the first set of intra-domain switches, a second set of intra-domain switches, and a set of inter-domain switches located between the first set of intra-domain switches and the second set of intra-domain switches, the method comprising: at an outside edge port of the intra-domain switch, inserting, in a packet that must travel between domains, an inter-domain routing prefix identifying both the source and destination domains; and passing the packet that must travel between domains to one of the inter-domain switches via an inside edge port of the intra-domain switch, the method further comprising: classifying an incoming packet as an ordered packet or an unordered packet; for an ordered packet, forwarding the incoming packet to a port identified by a spread routing table using a hash of source and destination identifications as a table index; and for an unordered packet, forwarding the incoming packet to a currently least utilized port, that leads to a root of the non-blocking switch fabric, having a smallest accumulator value, wherein an accumulator value for a port is increased by a value proportional to a length of each packet being forwarded to that port.