OSU Redundancy Switching for PON Service Continuity
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Solution Overview
Problem
In PON systems, FW updates cannot be performed quickly due to link interruptions during OSU switching, leading to instantaneous communication interruptions and prolonged restart times.
Innovation Solution
Implementing an OSU redundancy configuration where ONU information is periodically accumulated outside the OSU, allowing rapid reflection on a spare OSU during switching, and using a controller to manage the switching process, including buffering of down signals and stopping transmission permissions to prevent data loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If OSU switching is performed during FW updates, then service continuity can be maintained, but link interruptions occur causing communication delays and frame loss
Solution Approach 1:
The patent applies preliminary action by pre-accumulating ONU information outside the OSU in a storage unit before switching occurs. This allows the spare OSU to quickly acquire necessary information without waiting for transmission during switching, thereby maintaining service continuity while eliminating communication interruptions and frame loss.
2Productivity
If OSU switching is performed quickly, then FW update time is reduced, but data loss may occur during the switching process
Solution Approach 1:
The patent uses a concentration switch as an intermediary that buffers down signals during OSU switching. The switch temporarily holds incoming data and forwards it after switching is complete, enabling fast FW updates while preventing any data loss that would occur during the transition period.
Solution Approach 2:
The controller stops transmission permissions from the switching source OSU before actual switching occurs, preventing new data from being sent during the transition. This preliminary action ensures no data is lost while allowing the switching process to complete quickly.
3Reliability
If redundancy configuration is implemented, then service stability is improved, but device complexity increases
Solution Approach 1:
The patent merges the redundancy function into the existing OLT device by integrating the spare OSU, storage unit for ONU information, and concentration switch with buffering capabilities. This consolidation provides robust redundancy while avoiding the complexity of separate redundant systems, as the spare OSU shares resources with the active OSU.
Data Source
AI summary
A normal system OSU, a redundancy system OSU, an optical switch, a concentration switch, and a controller which detects a command input by operation control and performs control according to the command are provided, and in such a state that the controller detects a redundancy system switching command indicating that the normal system OSU is switched to the redundancy system OSU, the controller induces the concentration switch to change a storage destination of a down signal, instructs the normal system OSU which is the switching source OSU to stop transmission of a transmission permission message, instructs the optical switch to switch a path after receiving remaining data processing completion notifications from the concentration switch and the normal system OSU which is the switching source OSU, writes accumulated information about the normal system OSU, which is the switching source OSU, in the redundancy system OSU, and notifies the concentration switch of completion of switching, whereby a down signal is transmitted from the concentration switch.