Communication Line Switching Holdover Mechanism
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Solution Overview
Problem
In communication systems, resuming communication after a failure on a working line takes time due to the need for reestablishing a link through backup lines, which involves lengthy deregistration and reinitialization processes.
Innovation Solution
A method that includes a discovery step for registering ONUs, a holdover step where the ONU maintains link settings during line abnormalities, and a monitoring step to suppress timestamp drift errors, allowing for early resumption of communication by deferring the transition to a deregistered state until backup line switching is feasible.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the ONU directly shifts to a deregistered state upon detecting line abnormality, then the ONU can quickly reset and reinitialize the communication link, but it causes lengthy communication suspension time due to complete reestablishment procedures
Solution Approach 1:
The ONU performs preliminary actions by maintaining the logical link and link settings even after detecting line abnormality, instead of immediately deregistering. This allows the ONU to preserve configuration data and remain in a registered state, ready to quickly resume communication once the backup line is established, thereby reducing communication suspension time while maintaining link reliability
Solution Approach 2:
The invention introduces a holdover state as a cushioning mechanism between the registered state and deregistered state. During this holdover period, the ONU maintains link settings and suppresses timestamp drift error detection, providing a transitional buffer that prevents complete link termination and enables faster recovery without sacrificing communication reliability
2Loss of time
If the ONU maintains link settings during line abnormality in a holdover state, then communication resumption is faster, but timestamp drift errors may occur due to continued operation without full reset
Solution Approach 1:
The ONU applies preliminary anti-action by suppressing timestamp drift error detection during the holdover state. Instead of allowing normal timestamp drift monitoring that would trigger link disconnection, the system preemptively disables this detection mechanism during the transitional period, preventing false error signals that would otherwise cause unnecessary link termination and delay communication resumption
Solution Approach 2:
The invention dynamically adjusts the timestamp drift error detection mechanism based on the operational state. During the holdover state, timestamp drift detection is suppressed to maintain link stability, while in the registered state, normal detection resumes. This dynamic state-dependent behavior allows the system to maintain timestamp synchronization reliability while enabling faster communication resumption
Data Source
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AI summary
In a communication system in which a station-side line terminal apparatus 1 and a user-side line terminal apparatus 10 perform communication via a plurality of redundant physical lines, the user-side line terminal apparatus 10 monitors an out-of-synchronization error and line abnormality of the physical lines and, when line abnormality is detected (P4), shifts from a registered state to a holdover state for deferring discarding of setting information such as link information. The user-side line terminal apparatus 10 suppresses detection of the out-of-synchronization error during a deferred period to prevent a communication link from being disconnected by the out-of-synchronization error and prevent initial setting from being required. The station-side line terminal apparatus 1 switches a line during the deferred period (P7) and, after transmitting a synchronization signal (P8) to synchronize with the user-side line terminal apparatus, resumes normal communication.