Patent ID: 8762568

Claim:
A method comprising: establishing a virtual path over a first route in a backbone zone, wherein the backbone zone comprises a plurality of zones coupled to one another by a plurality of inter-zone links, the plurality of zones comprises a source zone and a destination zone, and the first route comprises at least one inter-zone link between a first border node of the source zone and a second border node of the destination zone; identifying a pre-planned alternative route in the backbone zone, wherein the pre-planned alternative route is between the first border node of the source zone and the second border node of the destination zone, and the pre-planned alternative route is automatically determined using a shortest path first (SPF) algorithm prior to detection of a first inter-zone link failure in the first route; detecting the first inter-zone link failure in the first route; establishing the virtual path over the pre-planned alternative route, in response to detection of the first inter-zone link failure comprising releasing link bandwidth used by the virtual path, and restoring the virtual path if the first inter-zone link failure indicates failure of the first border node of the source zone; detecting a second inter-zone link failure in the first route; configuring the pre-planned alternative route to pass through a transit zone upon detecting the second inter-zone link failure, wherein the transit zone comprises one or more tandem nodes used by the virtual path, and the tandem node neither originates or terminates the virtual path; and providing communication between the destination zone and the source zone via the pre-planned alternative route.