| 摘要 |
To restore partial outages within a communication network having numerous switching nodes and links interconnecting the nodes, a three-stage distributed restoration protocol is activated to use spare links to bypass failed links and restore normal network connectivity. The three-stage protocol detects and resolves contention for spare resources among separate restoration processes and is therefore particularly advantageous in the event of multiple simultaneous network failures. A conservative flooding approach is used during the first forward signalling stage. Data elements added to the forward signals convey the likelihood that the path will be needed for restoration. The second reverse signalling stage uses reverse signals with attached contention data to detect contention among separate processes for spare resources and to alert the respective processes. The final path implementation stage involves reviewing the reverse signals and using the attached contention data to make informed choices of restoration paths that result in the highest degree of overall network restoration. The present invention, including node logic and specific signal structures and multiple-pass signalling, allows for shared awareness among diverse restoration processes so that they may work collectively to best utilize available spare resources.
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