Patent ID: 7801156

Claim:
A method for routing a demand d={i, j} over a path p d between ports i and j in a multi-layer network having one or more wavelength selective switches, said method comprising the steps of: determining a middle layer node n in said multi-network for which there is a first path p i between said port i and said middle layer node n and a second path p j between said port j and said middle layer node n; ensuring that a layer number of nodes increases along a path; identifying a node n′, wherein said node n′ is a first node starting from port i that path p i shares with path p j ; and concatenating said path p d comprised of a subpath p′ i of said first path p i from said port i to said node n′ with a subpath of p′ j of said second path p j from said node n′ to said port j, wherein one or more of said steps are performed by a processor.