Ethernet Ring Protection Switching for Linear Chain Fault Recovery
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Solution Overview
Problem
Current communication networks, particularly Ethernet-based ones, lack effective protection switching mechanisms at layer two, leading to slow fault response times, inability to offer Quality of Service (QoS), complex circuitry, and hop-count limitations, especially when expanding to Metropolitan Area Networks (MANs) that require protection schemes for non-Ethernet Ring Protection Switching (ERPS) devices.
Innovation Solution
Implementing a protection switching method that instantiates ERPS on each communication device in a linear chain, identifies node or link faults using Continuity Check Messages (CCM) or other mechanisms, blocks ports, broadcasts fault messages, flushes Media Access Control (MAC) tables, and unblocks root port links to provide an alternate path for network traffic in Ethernet Ring Protected Switching (ERPS) networks, including both layer-2 and layer-3 communication networks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If Ethernet-based access and aggregation networks are designed in a tree structure, then network expansion is simplified, but network protection is lost
Solution Approach 1:
The patent segments the network into ERPS domains (Ethernet Ring Protection Switching domains) and non-ERPS domains, allowing different topologies to coexist. Each ERPS domain can form protected rings independently while connecting to non-ERPS devices through controlled interfaces, thus maintaining both protection capabilities and network expansion flexibility
Solution Approach 2:
The patent introduces a mediator mechanism at the boundary between ERPS and non-ERPS domains. When a fault is detected in an ERPS domain, the system uses intermediary messages to coordinate protection switching across domain boundaries, ensuring that non-ERPS devices are properly notified and adjusted without requiring them to understand full ERPS protocols
2Reliability
If ITU-T G.8032 ERPS is used for protection switching, then layer-2 protection is provided, but it cannot work with non-ERPS devices in MANs
Solution Approach 1:
The patent makes ERPS devices universally compatible with both ERPS and non-ERPS devices. Non-ERPS devices (such as IP/MPLS routers) can connect to ERPS domains through standard interfaces while still benefiting from ERPS protection. The system provides multi-functionality by handling both local ERPS faults and remote faults involving non-ERPS devices through standardized fault notification mechanisms
Solution Approach 2:
The patent implements a feedback mechanism where non-ERPS devices send fault notifications back to ERPS domains through standardized protocols. When a non-ERPS device detects a fault, it sends notifications that trigger appropriate protection switching actions in the ERPS domain, creating a closed-loop feedback system that maintains compatibility across different device types
3Area of stationary object
If ERPS messages pass through IP/MPLS cloud, then network coverage is extended, but message termination occurs at IP/MPLS nodes
Solution Approach 1:
The patent uses IP/MPLS nodes as intermediaries that properly terminate and forward ERPS fault messages. Instead of simply discarding these messages, the IP/MPLS nodes act as mediators that receive fault notifications from ERPS domains, process them appropriately, and forward them to the correct destinations, thus preventing information loss while enabling network coverage extension
4Ease of operation
If dual homed nodes are connected to VPLS network, then network connectivity is improved, but loop formations occur
Solution Approach 1:
The patent extracts the loop prevention function from the standard ERPS mechanism and enhances it specifically for dual-homed nodes connecting to VPLS networks. By identifying these specific node configurations and applying targeted block mechanisms, the system prevents loop formations while maintaining the connectivity benefits of dual homing without requiring changes to the entire ERPS protocol
Data Source
AI summary
The present invention relates to a protection switching method in a communication network, the communication network including plurality of communication devices forming a linear chain and at least one non-ERPS on the nodes ERPS (Ethernet Ring Protection Switching) device connecting terminal ports of the linear chain and thereby forming a ring. In one embodiment this is accomplished by instantiating ERPS on each communication device that forms a linear chain and on each non-terminal ports of the linear chain, identifying a node or link fault in the network, wherein the link or node fault is detected by Continuity Check Message (CCM), Loss of Light (LOL), Loss of Signal (LOS), Loss of periodic continuity check messages (IEEE 802.1 ag) or any other mechanisms thereof, blocking ports of the communication device in response to the detection of fault, periodically broadcasting a fault message by the blocked ports of the communication devices, wherein the message gets terminated at the ports of the communication device within the linear chain network without reaching the non-ERPS device, flushing the Media Access Control (MAC) table entry upon receipt of the fault message by all the communication device and unblocking of a root port link (RPL) of the linear for providing an alternate path to route network traffic after receipt of the fault message.