Patent ID: 6862263

Claim:
A method for use in a network that carries traffic over paths comprising high-level and low-level nodes interconnected by links, said traffic including local traffic that is routed by at least one of the low-level nodes and further includes express traffic that is communicated between at least one pair of high-level nodes over a path that includes said at least one of the low-level nodes, said express traffic passing through said at least one of the low-level nodes without being routed by that low-level node, there being at least one other path between said pair of high-level nodes that includes said at least one of the low-level nodes, the method comprising responding to an error condition affecting a link carrying both said local and express traffic by rerouting at least that express traffic around the affected link to its original destination, the rerouting of said express traffic being carried out by at least one of said high-level nodes without being rerouted by any low-level node that lies on any other path between said pair of high-level nodes.