Ethernet OAM Link Connectivity Detection Using State Machine Waiting
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Solution Overview
Problem
During the start-up of Ethernet OAM circuits, connectivity errors are falsely reported due to the time lag in operator enabling both ends of a link, leading to incorrect reporting of link connectivity issues, especially at faster CCM transmission rates.
Innovation Solution
Implementing a state machine with an additional WAITING state that delays the commencement of connectivity checking until a predetermined number of valid connectivity check messages are received, using an existing in-band data path to ensure link continuity before initiating connectivity checks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If connectivity checking is enabled immediately during start-up, then connectivity errors can be detected promptly, but false errors are reported due to operator delay in enabling both link ends
Solution Approach 1:
The patent applies preliminary action by introducing a WAITING state before the connectivity monitoring state. During this waiting period, the system performs preliminary actions (receiving and counting CCM messages) to ensure the link is stable and both ends are operational before connectivity checking begins. This prevents false error reporting while maintaining timely detection capability.
2Speed
If CCM transmission rate is increased to improve error detection speed, then connectivity errors are detected faster, but false errors occur more frequently during start-up due to operator delay
Solution Approach 1:
The patent uses preliminary action by requiring a predetermined number of CCM messages to be received during the WAITING state before connectivity monitoring begins. This preliminary validation ensures that even at high transmission rates, the system only starts monitoring when the link is confirmed stable, preventing false errors while maintaining fast detection capability.
Solution Approach 2:
The patent introduces an intermediary mechanism (the WAITING state with message counting) between CCM transmission and connectivity monitoring. This intermediary validates link stability before enabling monitoring, acting as a buffer that prevents high-rate transmissions from causing false errors during operator delay periods.
3Reliability
If a waiting period is introduced before connectivity monitoring to ensure link stability, then false error reporting is reduced, but the time to detect actual connectivity errors increases
Solution Approach 1:
The patent applies preliminary action by performing link validation (receiving predetermined number of CCMs) before enabling connectivity monitoring. This ensures false errors are prevented while the system quickly transitions to monitoring mode once validation is complete, minimizing overall detection latency.
Solution Approach 2:
The patent uses dynamics by making the system adaptive - the WAITING state duration is not fixed but depends on receiving the predetermined number of CCM messages. Once this dynamic condition is met, the system automatically transitions to monitoring mode, optimizing the balance between preventing false errors and enabling fast error detection.
Data Source
AI summary
A method of commencement of operation of a communication system such as an Ethernet OAM system enables an endpoint (A) to transmit and receive repetitive connectivity check messages on a link between the endpoint and a remote endpoint (B). A loss of connectivity with the remote endpoint is determined by the absence of received connectivity check messages within a monitoring interval. The commencement of the monitoring interval is delayed until a predetermined number of valid connectivity check messages has been received. The method may be implemented by use of a counter for received connectivity check messages and an additional waiting state in a state machine.