Background Path Computation for Millisecond Optical Restoration
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Solution Overview
Problem
Conventional real-time path computation elements (PCEs) in optical networks take significant time to compute alternate paths for path restoration due to complex meshed networks, often taking minutes to complete, which is not feasible for tight restoration time requirements.
Innovation Solution
Implement a background path computation element (BK-PCE) that precomputes alternate optical paths during normal network operation and stores them in a database, allowing for quick lookup and deployment when failures occur, reducing restoration time to milliseconds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If real-time path computation is performed by conventional PCE after failure report, then path restoration is achieved, but restoration time is too long (minutes)
Solution Approach 1:
The patent precomputes multiple alternate optical paths in advance and stores them in a database before failures occur. When a failure happens, the system performs a database lookup instead of real-time computation, reducing restoration time from minutes to milliseconds while maintaining reliable path restoration capability.
2Reliability
If multiple alternate optical paths are computed and validated in real-time, then a restorative path satisfying all constraints is found, but computation time increases to tens of minutes
Solution Approach 1:
The system precomputes and validates multiple alternate optical paths against all path constraints before failures occur, storing only the validated paths in a database. This eliminates real-time validation overhead, ensuring constraint satisfaction while reducing computation time from tens of minutes to milliseconds during actual restoration events.
Solution Approach 2:
The patent extracts and stores only the essential path information (route, constraints, validation status) in a database, separating the computationally intensive validation process from the real-time restoration decision process. This allows quick lookup of pre-validated paths without repeating the full validation computation.
3Reliability
If complete solution analysis considering different network layers is performed, then comprehensive path restoration is achieved, but analysis time increases significantly
Solution Approach 1:
The patent performs complete multi-layer solution analysis (optical, OTN, IP layers) in advance during path precomputation, storing the results in a database. When failures occur, the system retrieves pre-analyzed paths without repeating the multi-layer analysis, achieving comprehensive restoration coverage while reducing analysis time from significant duration to milliseconds.
Data Source
AI summary
A method performed at a controller of an optical network configured with an optical path comprising a series of fiber spans for forwarding traffic: as a background operation to forwarding the traffic along the optical path, generating and storing precomputed optical paths as alternates to the optical path for path restoration by simulating some number of faults impacting the optical path; upon receiving, from the optical network, a path restoration query that indicates actually failed fiber spans, determining availability of a precomputed optical path that avoids the actually failed fiber spans; and when the precomputed optical path is available, sending, to the optical network, a first descriptor of the precomputed optical path to enable a deployment of the precomputed optical path. The method drastically reduces the time of alternate path research in complex meshed networks.