FEC Line Switching With Buffer Resequencing for Hitless Protection
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Solution Overview
Problem
In 1:1 protection schemes, packet loss or sequence changes occur due to delay differences between communication lines, making preventive maintenance line switching impossible.
Innovation Solution
A transmission system with a first communication device and a second communication device connected via a first line for frame transmission, a second line for error-correction coding, and a third line for communication in case of failure, using buffers to manage frame switching based on error correction status without causing packet loss or sequence changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If line switching is performed in 1:1 protection scheme, then communication reliability is improved, but packet loss or sequence changes occur due to delay differences between lines
Solution Approach 1:
The invention transmits a pre-switching message before actual line switching occurs. This allows the receiving end to prepare buffer storage in advance, ensuring that packets arriving from different speed lines are properly buffered and resequenced, preventing packet loss during the transition
2Reliability
If line switching is performed in 1:1 protection scheme, then communication reliability is improved, but sequence changes occur due to delay differences between lines
Solution Approach 1:
The invention introduces a buffer as an intermediary between the switching mechanism and the packet flow. The buffer temporarily stores packets from different lines, allowing them to be resequenced in the correct order before being forwarded, thus maintaining packet sequence stability during line switching
Solution Approach 2:
The pre-switching message triggers preliminary buffer allocation and preparation at the receiving end before switching occurs. This advance preparation ensures that the buffer is ready to handle packets from the new line and maintain proper sequencing
Data Source
AI summary
When a first communication device receives a predetermined message from a second communication device via a third line (L3) in a state of transmitting frames to a first line (L1) while performing error-correction coding on the frames, the first communication device switches the line used for transmission from L1 to the second line (L2), then transmits a frame of a post-switching message to L1 . The second communication device receives frames from L1 and L2 and performs error correction, stores the frames, on which error correction has been performed, in first and second buffers (B1, B2), and when determining that it is necessary to perform line switching based on the status of error correction with respect to the frames received from L1, transmits a predetermined message to L3, and when receiving the frame of the post-switching message from L1, starts reading frames from B2 after reading all frames stored in B1.