Ethernet Ring Loop Detection via Dedicated Frames

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Solution Overview

Problem

Ethernet Ring Protected networks are prone to data packet loops due to provisioning, hardware, and protocol-related issues, which conventional mitigation strategies may not fully address, leading to network downtime and incorrect information about port statuses.

Innovation Solution

Implementing a loop detection method using an Ethernet Virtual Local Area Network (E-VLAN) service that periodically transmits loop detection frames on both ports of a node, automatically determining loop existence and initiating recovery actions such as forced switches or port shutdowns, with additional data for root cause analysis.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional mitigation strategies (ports blocked, guard timers, R-APS frame dropping) are used to prevent loops, then loop avoidance is improved, but device complexity and difficulty of detecting actual loops increase

Engineering Contradiction:

Improveloop avoidanceVSAvoidprotocol complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent introduces a dedicated loop detection frame as an intermediary mechanism that travels around the ring to detect loops. This separate detection mechanism operates independently from the data traffic and conventional protection protocols, providing clear loop detection without adding complexity to the existing G.8032 protocol stack.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The loop detection frame provides feedback by returning to the source node after circulating the ring. When the source node receives its own detection frame, it confirms the presence of a loop. This feedback mechanism enables automatic loop detection and recovery without requiring complex centralized monitoring.

Inventive Principle:

Principle #23Feedback

2Difficulty of detecting and measuring

If MAC movement monitoring is used to detect loops, then loop detection capability is improved, but automation and applicability to all loop types decrease

Engineering Contradiction:

Improveloop detection capabilityVSAvoidcentralized analysis requirement

Core Design Contradiction:

Difficulty of detecting and measuringVSExtent of automation

Solution Approach 1:

Each node in the ring independently generates and processes loop detection frames without requiring centralized MAC table analysis. The detection is fully automated at the distributed level, with nodes autonomously determining loop presence based on receiving their own detection frames, eliminating the need for centralized control.

Inventive Principle:

Principle #25Self-service

3Speed

If fast ERP solutions are implemented, then network speed and recovery time are improved, but the need for additional robust loop detection mechanisms increases

Engineering Contradiction:

Improverecovery speedVSAvoidloop detection robustness

Core Design Contradiction:

SpeedVSReliability

Solution Approach 1:

The loop detection frames are continuously circulating in the ring before any failure occurs, ready to immediately detect loops when they form. This preliminary presence of detection traffic enables instant loop detection and recovery, matching the speed requirements of fast ERP solutions while providing robust detection coverage.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS10091023B2Systems and methods to detect and recover from a loop in an Ethernet ring protected network

Publication Date: 2018.10.02 CIENA CORP

AI summary

Loop detection systems and methods in an Ethernet Ring Protected network include, subsequent to creating a loop detection service on all nodes in the network, periodically transmitting a loop detection frame on both ports of the node; responsive to failing to receive the loop detection frame at the node, determining no loop exists in the ring; and, responsive to receiving the loop detection frame on a received port at the node, determining a loop exists in the ring and automatically implementing one or more recovery actions.