| 摘要 |
A method and apparatus are disclosed for monitoring and signaling a path restoration using pre-computed restoration paths following a detected fault on a primary service path in a communications network. A fault occurring inside the restorable portion of a network in heterogeneous or multiple network environments can be distinguished from faults occurring outside the restorable network in accordance with the ANSI Tandem Connection Maintenance standard, T1.105.05-1994. Path restoration is activated only when a fault causing path failure occurs inside the restorable portion of the network. Each conforming node in the restorable portion of the network has the necessary monitoring, signaling and cross-connect functionality and databases to participate actively in real time restoration. Additional non-conforming network elements can be positioned between the restoration nodes without preventing path restoration. With the signaling architecture of the present invention, when an end-node detects a path failure caused by an in-network fault, it formulates a signaling message for restoring the failed path. The restoration signaling message is thereafter relayed from one node to another in the overhead or payload of signaling paths that occupy the same bandwidth that is subsequently used by the restoration path. Once a signaling message is transmitted to an adjacent node in the overhead or payload of a particular signaling path, the node that transmitted the message makes a cross-connect that replaces the signaling path with a segment of the restoration path whose set-up was requested in the transmitted signaling message.
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