Photonic Routing Loop Avoidance via Wavelength Selective Switches
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Solution Overview
Problem
Conventional photonic networks face complexity in routing individual optical channels due to impairment effects and signal loss, and struggle with restoration from line faults at the speed required for protection, especially in campus, metro, and regional networks.
Innovation Solution
The implementation of a photonic network with a routing protocol that computes loop-free paths using Layer 2 or Layer 3 constructs, such as Spanning Tree Protocol and Shortest Path Bridging, to quickly and efficiently route wavelengths or groups of wavelengths, adapting techniques from Ethernet packet bridging and IP packet routing to the photonic domain, and utilizing wavelength selective switches to block wavelengths and reconfigure paths in response to link failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If conventional routing methods are used in photonic networks, then routing complexity is managed through impairment effects and signal loss considerations, but restoration speed from line faults is insufficient for protection requirements
Solution Approach 1:
The patent replaces conventional electronic routing control with photonic routing using optical circulators and wavelength selective switches that operate at the speed of light. The routing decisions are made optically rather than electronically, enabling restoration speeds that meet protection requirements while managing complexity through photonic domain constructs.
Solution Approach 2:
The patent introduces photonic domain constructs as intermediaries between physical optical components and routing control. These constructs enable rapid loop-free path computation by translating routing problems into the photonic domain, where they can be solved at optical speeds without the complexity of conventional electronic routing algorithms.
2Productivity
If loop avoidance techniques are implemented using photonic domain constructs, then loop-free paths are computed rapidly for wavelengths, but the system requires adaptation of Layer 2 or Layer 3 constructs to the photonic domain
Solution Approach 1:
The patent adapts universal Layer 2 and Layer 3 routing constructs to the photonic domain, creating multi-functional photonic domain constructs that can handle various routing scenarios. These constructs provide a unified framework for loop avoidance that works across different network configurations and wavelength scenarios, improving productivity while managing complexity through standardization.
3Reliability
If wavelength selective switches are used to block wavelengths and reconfigure paths, then rapid response to link failures is achieved, but device complexity increases due to optical components at each node
Solution Approach 1:
The patent segments the network into nodes with standardized optical components, where each node contains wavelength selective switches and optical circulators. This segmentation allows independent optimization of each node while maintaining overall network reliability, as failure isolation and recovery can occur at the node level without affecting the entire network.
Solution Approach 2:
The patent uses wavelength selective switches to dynamically change the blocking state of specific wavelengths at each node based on routing decisions. By changing the blocking parameter of optical components rather than physically reconfiguring connections, the system achieves rapid response to failures while managing component complexity through programmable control.
Data Source
AI summary
A photonic network includes a plurality of nodes each supporting add and drop of at least Y wavelengths, a plurality of optical links interconnecting the plurality of nodes, the plurality of optical links support up to X wavelengths and Y≦X, an optical routing protocol configured to compute a loop-free path through the plurality of nodes on the plurality of links, the loop-free path is computed for one of the X wavelengths or a group of the X wavelengths using routing constructs adapted to a photonic domain, and optical components at each of the plurality of nodes configured to selectively block at least one of the X wavelengths based on the computed loop-free path. A photonic routing method and photonic node are also disclosed.