Control Plane Fabric Switchover on Shared Boards
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Solution Overview
Problem
Network devices face challenges in minimizing interruption and resource taxation during transitions to backup components due to complex and time-consuming failure recovery processes, especially when components malfunction or go out-of-service.
Innovation Solution
Implementing a redundant configuration with two control boards, each having a control plane and a fabric plane, where one control board is designated as active and the other as standby, allowing for seamless switching of control and fabric planes without disrupting traffic, thereby minimizing switchover times and resource usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a backup component is configured to take over when a component fails, then reliability is improved, but device complexity and switchover time increase
Solution Approach 1:
The network device is segmented into two independent control boards, each with its own control plane and fabric plane. This segmentation allows the system to isolate failures to individual boards while maintaining overall functionality through the other board, reducing the complexity of failover procedures compared to a monolithic architecture.
Solution Approach 2:
The standby control board is pre-configured with all necessary control plane and fabric plane resources before any failure occurs. This preliminary preparation ensures that when a failure happens, the standby board can immediately take over without requiring complex real-time reconfiguration, thus reducing switchover time and operational complexity.
2Reliability
If a standby component is prepared for failure recovery, then reliability is improved, but resource overhead increases
Solution Approach 1:
Each control board is designed to be universal, capable of performing both control plane and fabric plane functions. The standby board maintains all necessary resources in a ready state, allowing it to assume any failed function without requiring additional specialized components. This multi-functionality reduces resource overhead compared to having dedicated backup components for each function.
Solution Approach 2:
The control plane and fabric plane are merged onto the same control board, creating an integrated unit. This merging reduces the total number of separate components needed in the system, as each board self-contains both functional planes. The standby board combines all necessary resources in one package, reducing overall resource overhead while maintaining full redundancy capability.
3Device complexity
If control plane and fabric plane are on the same board, then device complexity is reduced, but reliability during switchover is compromised
Solution Approach 1:
The system is segmented into two independent control boards, each containing both control plane and fabric plane. This segmentation creates physical separation of failure domains while maintaining functional integration on each board. The independence of the two boards ensures that a failure on one board does not affect the other, preserving reliability during switchover despite the simplified architecture.
Solution Approach 2:
The system dynamically changes the operational status parameter of each control board between active and standby states. This parameter change allows the system to maintain a simplified architecture with control and fabric planes on the same board while ensuring reliability through the ability to switch to a pre-configured standby board with identical capabilities.
Data Source
AI summary
A network device includes a first and a second control board, with each control board having a separate control plane and fabric plane. The network device is configured to establish an active control plane on the first control board and an active fabric plane on the second control board. The network device is configured to establish a standby fabric plane on the first control board and a standby control plane on the second control board. The network device is configured to detect a failure on the first control board or the second control board and switch the status of the control plane on the second control board from standby to active, when the failure is on the first control board, and switches the status of the fabric plane on the first control board from standby to active when the failure is on the second control board.