Inverse Multiplexing Synchronization Recovery via Cell Insertion
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Solution Overview
Problem
Current multiple-link communication systems, such as Inverse Multiplexing for Asynchronous Transfer Mode (IMA), face challenges in quickly recovering synchronization after cell loss or duplication, leading to prolonged downtime and disruptions in user data traffic due to the need for link resets, which are not efficiently addressed by existing specifications.
Innovation Solution
A synchronization monitor and recovery module are implemented to detect errors in synchronization information across communication links, allowing for the insertion or removal of communication traffic to maintain alignment, thereby reducing protection switching time and achieving synchronization within the 60 ms APS standard.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If link reset is performed to recover synchronization after cell loss or duplication, then synchronization is restored, but user data traffic is disrupted for several seconds
Solution Approach 1:
The patent performs preliminary actions by detecting cell loss or duplication conditions and initiating recovery procedures before complete synchronization failure occurs. The system monitors ICP cells and detects alignment errors early, allowing it to perform corrective actions (inserting/removing cells) before the link completely loses synchronization, thereby avoiding full link resets and reducing downtime.
Solution Approach 2:
The patent introduces an intermediary recovery mechanism that operates between normal operation and full link reset. Instead of directly resetting the link when synchronization is lost, the system uses an intermediate recovery process that inserts or removes IMA cells to realign the frame structure, maintaining link continuity while restoring synchronization, thus avoiding complete link disruption.
2Reliability
If link reset is performed to recover frame alignment, then alignment is restored, but entire IMA group remains down during re-negotiation
Solution Approach 1:
The patent extracts the frame alignment recovery process from the overall link reset operation. By detecting alignment errors and performing targeted recovery (inserting/removing specific IMA cells) on individual links rather than resetting the entire IMA group, the system isolates the recovery action to only what is necessary, allowing other links in the group to continue carrying user traffic during the recovery process.
Solution Approach 2:
The patent segments the IMA group into individual links for independent monitoring and recovery. Each link can be realigned independently through cell insertion or removal without affecting other links in the group. This segmentation allows partial group operation during recovery, maintaining productivity while restoring frame alignment on affected links.
3Reliability
If Hunt state is entered to regain link synchronization, then synchronization is recovered, but recovery takes longer than acceptable time
Solution Approach 1:
The patent skips the lengthy Hunt state recovery process by implementing a faster alignment recovery mechanism. When alignment errors are detected, the system immediately performs corrective actions (inserting or removing IMA cells) to realign the frame structure, rushing through the recovery process in a single pass rather than iteratively searching for synchronization, thereby reducing recovery time to within the 60 ms APS standard.
Data Source
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AI summary
Apparatus and methods of recovering synchronization for multiple-link communications are disclosed. Streams of communication traffic on a plurality of communication links from which communication traffic is to be extracted and combined into a single communication traffic stream are monitored for receipt of synchronization information for each link. In the event that an error occurs in receipt of the synchronization information for any of the communication links, a stream received on each affected link is modified. For example, traffic may be removed from or inserted into a received stream where synchronization information for a link is received twice or received earlier than expected, respectively. If synchronization information for a link is missing, then it may be generated and inserted into the stream received on that link. In some embodiments, synchronization information includes sequence numbers, and inter-link synchronization is re-aligned to received sequence numbers when expected and received sequence numbers do not match.