Multicast Control Traffic for Optical Protection Switching
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Solution Overview
Problem
Protection switching in optical networks can be rendered inoperable by spanning tree protocol (STP) when it detects a protection path as a loop, leading to issues with multicast traffic forwarding, resulting in excessive flooding and dropped traffic due to the lack of interoperability between STP and protection switching protocols.
Innovation Solution
A method where multicast control traffic is communicated to both the working and protection paths of a protection switching group, and processed as if received via both paths, ensuring seamless switching and minimizing traffic disruption during path changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If protection switching is implemented to provide redundant paths, then network reliability is improved, but spanning tree protocol detects the protection path as a loop and breaks it, making protection switching inoperable
Solution Approach 1:
The patent segments the network protocol handling into two distinct parts: protection switching operations and spanning tree protocol operations. By treating multicast control traffic differently from data traffic and allowing simultaneous operation of both protocols without mutual interference, the system maintains both redundant paths and loop prevention independently, resolving the conflict between reliability and protocol interoperability
Solution Approach 2:
The patent introduces multicast control traffic as an intermediary mechanism that enables communication between protection switching and spanning tree protocol. This control traffic allows the spanning tree protocol to recognize and accept the protection path topology without detecting it as a harmful loop, while still maintaining the protection switching functionality. The intermediary resolves the protocol conflict by providing a communication channel that reconciles both protocols' requirements
2Stability of the object's composition
If spanning tree protocol breaks the protection path to prevent loops, then loop-free topology is maintained, but protection switching becomes inoperable
Solution Approach 1:
The patent applies local quality by allowing different protocol behaviors in different network contexts. Specifically, the spanning tree protocol is configured to treat protection paths differently when multicast control traffic is present versus when it is absent. This localized differentiation enables the protection path to remain active for reliability purposes while maintaining loop-free topology through controlled protocol interactions
3Reliability
If protection switching switches between working and protection paths, then path redundancy is maintained, but switching/routing protocols become unaware of the active path, causing traffic drops and flooding
Solution Approach 1:
The patent implements feedback mechanisms through multicast control traffic that continuously informs switching and routing protocols about the active path status. When a protection switch occurs, the control traffic provides real-time feedback to update protocol awareness, preventing traffic drops and unnecessary flooding by keeping the control plane synchronized with the data plane path changes
4Device complexity
If multicast topology is learned only on the active path, then multicast forwarding is simplified, but traffic is flooded or dropped during topology recomputation after path switching
Solution Approach 1:
The patent applies preliminary action by pre-learning multicast topology on both working and protection paths before switching occurs. This advance preparation ensures that when a protection switch happens, the network element already has the necessary topology information ready, eliminating the need for topology recomputation and preventing traffic flooding or drops during the transition
Data Source
AI summary
In accordance with embodiments of the present disclosure, a method is provided for communicating multicast traffic. The method may include in response to receipt of multicast control traffic at a network element to be communicated to a protection switching group, communicating the multicast control traffic to each of a working path and a protection path of the protection switching group. The method may also include in response to receipt of multicast control traffic via either of the working path and the protection path, processing the multicast control traffic as if the multicast control traffic was received via both the working path and the protection path.