Patent ID: 7113481

Claim:
A method of dynamically allocating protection paths in a wavelength-division multiplexed network including a plurality of nodes coupled by communication links, comprising the steps of: in each node, maintaining a database of information regarding the status of the network including information associating channels in each link of the node to one or more protection paths and information associating channels in each link to respective working paths; in response to receiving a request for a new protection path to protect a defined working path in one of said nodes: using the database of said one node to identify links that have at least one shareable channel which may be shared between the new protection path and one or more existing protection paths; using the database of said one node to identify links that do not have a shareable channel but do have an unused channel that may be used for said new protection path; assigning weighted costs to said identified links, where links that have at least one shareable channel are assigned a lower cost than links that do not have a shareable channel but do have an unused channel; and determining a protection path using said identified links based on said costs, such that links not having at least one shareable channel are disfavored relative to links having at least one shareable channel.