Impairment-Aware Routing in WDM Optical Networks
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Solution Overview
Problem
Wavelength division multiplexing (WDM) networks face challenges in routing and wavelength assignment due to optical impairments, which affect signal quality and require consideration of physical processes in optical fibers and devices, leading to signal degradation and increased bit error rates.
Innovation Solution
The implementation of impairment-aware routing and wavelength assignment (IA-RWA) systems using Path Computation Element (PCE) protocols like PCEP and GMPLS, which consider network component characteristics and impairment impacts on light propagation, employing various architectures such as combined, separated, and distributed IA-RWA architectures to validate and optimize lightpaths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional routing and wavelength assignment is used without considering optical impairments, then the routing process is simpler and faster, but signal degradation occurs and bit error rates increase
Solution Approach 1:
The system performs preliminary impairment awareness by pre-calculating and storing impairment metrics for different lightpaths during the routing computation phase. This allows the routing algorithm to select paths that inherently minimize optical impairments before signal transmission begins, thereby improving signal quality without adding complex real-time monitoring equipment.
Solution Approach 2:
The system implements feedback mechanisms where impairment measurements from actual signal transmission are fed back into the routing and wavelength assignment database. This feedback loop continuously refines the impairment metrics, enabling the system to learn and adapt to changing network conditions, thus improving reliability while maintaining manageable complexity through intelligent algorithms.
2Reliability
If impairment-aware routing and wavelength assignment is implemented, then signal degradation is reduced and bit error rates improve, but the routing computation becomes more complex
Solution Approach 1:
The system pre-computes impairment metrics and stores them in a database during network planning and initial setup phases. When routing decisions are needed, the system queries this pre-computed data rather than performing complex real-time impairment calculations, significantly reducing computation time while still achieving impairment-aware routing that improves bit error rates.
Solution Approach 2:
The routing computation is segmented into separate phases: impairment metric collection, database construction, and routing decision-making. By dividing the complex computation into these manageable segments, the system can perform detailed impairment analysis offline and use simpler query-based routing online, thus improving reliability without excessive computation time during critical routing events.
3Reliability
If optical impairments are considered during path selection, then signal propagation reliability is improved, but the path computation constraints increase
Solution Approach 1:
The system introduces an intermediary impairment database that acts as a mediator between the physical optical network and the routing computation layer. This database stores pre-processed impairment metrics and translates complex physical layer characteristics into simplified routing constraints, enabling path computation to consider signal propagation reliability without directly handling the full complexity of optical impairment models.
Data Source
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AI summary
An apparatus comprising a path computation element (PCE) configured for at least partial impairment aware routing and wavelength assignment (RWA) and to communicate with a path computation client (PCC) based on a PCE protocol (PCEP) that supports path routing, wavelength assignment (WA), and impairment validation (IV). Also disclosed is a network component comprising at least one processor configured to implement a method comprising establishing a PCEP session with a PCC, receiving path computation information comprising RWA information and constraints from the PCC, establishing impairment aware RWA (IA-RWA) based on the path computation information and a private impairment information for a vendor's equipment, and sending a path and an assigned wavelength based on the IA-RWA to the PCC. Disclosed is a method comprising establishing impairment aware routing and wavelength assignment for a plurality of network elements (NEs) in an optical network using routing and combined WA and IV.