LC-Mode Interconnecting Ring Closure Using Periodic MRP Frames
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Solution Overview
Problem
In MRP compliant networks, when a Media Redundancy Interconnection Client (MIC) reboots, the interconnect link comes up before the MRP state-machine is restored, leading to a complete traffic drop due to the network transitioning to an Interconnect-Open state, which can last from 1 to 30 seconds until the state-machine is operational again.
Innovation Solution
A Media Redundancy Interconnection Manager (MIM) in Link Check mode sends periodic INLNK_UP MRP frames and transitions to a Check Interconnection Closed State upon receiving specific frames, reducing the degraded mode duration by managing the Interconnecting ring's transition from Interconnect-Open to Interconnect-Closed state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the interconnect link comes up before the MRP state-machine is restored after MIC reboot, then the link is established, but the network transitions to Interconnect-Open state causing complete traffic drop
Solution Approach 1:
The MIM performs preliminary actions by sending test frames through interconnection ports before fully restoring the MRP state-machine. This proactive approach ensures that the interconnection topology is verified in advance, preventing unnecessary transitions to Interconnect-Open state and maintaining traffic continuity during the state-machine restoration process
Solution Approach 2:
The system implements feedback mechanisms where the MIM monitors the state of MRP state-machines in MICs and adjusts its behavior accordingly. By receiving feedback about the operational status of neighboring devices, the MIM can make informed decisions about maintaining or changing interconnection states, thereby avoiding unnecessary traffic disruption
2Reliability
If the MIM waits for MRP state-machine to be operational before restoring interconnection, then traffic continuity is maintained, but the recovery time increases
Solution Approach 1:
The MIM dynamically adjusts its operational mode based on the current state of the network and MRP state-machines. Instead of statically waiting for full state-machine restoration, the MIM transitions between different operational states (e.g., from blocked to forwarding) based on real-time conditions, optimizing both traffic continuity and recovery speed
Solution Approach 2:
The system changes operational parameters such as the state of interconnection ports and the timing of test frame transmissions based on the recovery phase. By adjusting these parameters dynamically during the restoration process, the system achieves faster recovery while maintaining acceptable traffic continuity
3Measurement precision
If the MIM sends test frames frequently to detect interconnection status, then detection accuracy improves, but network overhead increases
Solution Approach 1:
The MIM sends test frames through interconnection ports at periodic intervals rather than continuously. This periodic action is sufficient to detect changes in interconnection status (such as when a MIC's state-machine becomes operational) while minimizing the amount of test traffic injected into the network, thus balancing detection accuracy with overhead reduction
Data Source
AI summary
A method and system are devised for improved Interconnecting ring transition from open to closed state. The Interconnecting ring comprises a Media redundancy Interconnection Manager, MIM and at least three Media redundancy Interconnection Clients, MICs, the MIM being in Link Check, LC, mode. When the Interconnecting ring is in open state, and upon the MIM receiving a first one of first INLNK_UP MRP frames sent by one of the MICs, the MIM starts sending periodic second INLNK_UP MRP frames, changes to Check Interconnection, Interconnection Closed State, CHK_IC, state and the Interconnecting ring to closed state, if the MIM receives one of the second INLNK_UP MRP frames, or a second one of the first INLNK_UP MRP frames.