Multi-Chassis Trunking Control Table Sync for Graceful Switchover
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Solution Overview
Problem
Existing stacking systems face challenges in implementing hot standby or hitless switchover, particularly when using alternative control protocols like MCT, leading to degraded performance and dropped traffic.
Innovation Solution
A stacking system with an active and standby computer network device that synchronizes system control tables and hardware through reprogramming or downloading, using MAC, spanning tree, and link aggregation group tables, ensuring minimal disruption during switchover.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a standby unit is designated to take over when the active unit fails, then system reliability is improved, but device complexity increases due to the need for switchover mechanisms and state synchronization
Solution Approach 1:
The standby unit performs preliminary actions by pre-loading system control tables and maintaining synchronization with the active unit before failure occurs. This allows the standby unit to immediately assume the active role without requiring complex real-time synchronization during switchover, thereby improving reliability while managing complexity through advance preparation
Solution Approach 2:
The standby unit maintains a copy of the system control tables from the active unit. This copying mechanism simplifies the switchover process by allowing the standby unit to directly use the pre-copied tables without complex real-time data exchange, reducing the complexity of the switchover mechanism while ensuring system reliability
2Loss of energy
If hot standby or hitless switchover is implemented, then traffic loss is reduced, but implementation difficulty increases particularly with alternative control protocols like MCT
Solution Approach 1:
The system performs preliminary synchronization of system control tables between active and standby units before switchover is needed. This advance preparation enables hitless switchover with minimal traffic loss by ensuring the standby unit already has the necessary control information, while avoiding the implementation difficulties of complex real-time protocols during the actual switchover event
Solution Approach 2:
The system uses an intermediary mechanism where the active unit provides system control table information to the standby unit through controlled data exchange. This intermediary approach simplifies implementation by using standardized table formats and controlled synchronization protocols, making hot standby feasible with alternative control protocols like MCT while minimizing traffic loss
3Productivity
If system control tables are synchronized between active and standby units, then switchover performance is improved, but data processing overhead increases
Solution Approach 1:
The system applies local quality by selectively synchronizing only the specific system control tables that are critical for switchover (such as MAC address tables, spanning tree tables, and link aggregation tables) rather than all possible data. This targeted approach improves switchover performance by ensuring essential information is available while minimizing data processing overhead by excluding non-critical data from synchronization
Data Source
AI summary
A stacking system that includes multiple computer network devices (such as a switch or a router) is described. This stacking system may include: an active computer network device that implements software for control protocols and user configuration of the stacking system, and a standby computer network device that provides switchover backup for the active computer network device. During operation of the stacking system, when a switchover from the active computer network device to the standby computer network device occurs, at least the standby computer network device performs an action based at least in part on differences between system control tables for the active computer network device and the standby computer network device, wherein the action comprises: reprograming at least part of the system control tables; reprogramming at least part of hardware in the stacking system; or downloading at least the part of the system control tables to the hardware.