SDN Sub-Controller Switching for Controller Failure Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing SDN systems face challenges in reliably determining an anomalous state of the SDN controller, which can lead to communication failures when the controller is not functioning properly.
Innovation Solution
The SDN system incorporates an SDN sub-controller that executes a switching process when keepalive notifications from the SDN controller are not received within a specific period and switching requests are detected from a majority of SDN switches, ensuring reliable control even if the primary SDN controller is in an anomalous state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the SDN system uses a single SDN controller to manage communication settings, then the system structure is simple, but the reliability deteriorates when the controller becomes anomalous
Solution Approach 1:
The controller function is segmented into a primary SDN controller and a standby SDN sub-controller. The SDN switch is also segmented to independently monitor the primary controller and autonomously switch to the sub-controller when needed, dividing the single-point-failure risk into multiple redundant components.
Solution Approach 2:
The system changes the operational state parameter of the controller from a single active state to a dual-state configuration (primary and standby). By maintaining the sub-controller in a standby state with identical functional capabilities, the system achieves hot-standby redundancy without significantly increasing structural complexity.
2Reliability
If the SDN system implements a switching mechanism between controllers, then the reliability improves during anomalies, but the device complexity increases
Solution Approach 1:
The SDN switch is empowered with self-service capabilities to autonomously detect controller anomalies through keepalive notification monitoring and automatically execute switching to the standby sub-controller without requiring complex external control or manual intervention, simplifying the overall switching mechanism.
Solution Approach 2:
A feedback mechanism is implemented where the SDN switch continuously monitors keepalive notifications from the primary controller and automatically triggers switching when notifications are missed, creating a simple yet reliable closed-loop control system that balances reliability with minimal complexity.
3Loss of time
If the SDN switch autonomously switches to the sub-controller, then the response time improves during anomalies, but the measurement precision of controller status deteriorates
Solution Approach 1:
The SDN switch performs preliminary actions by continuously monitoring keepalive notifications in advance and maintaining a readiness state for switching. This allows the system to detect anomalies promptly and execute switching with minimal delay while maintaining accurate status measurement through ongoing monitoring.
Solution Approach 2:
The system applies preliminary anti-action by implementing a threshold-based anomaly detection mechanism that requires multiple missed keepalive notifications before triggering a switch, preventing premature switching due to transient network issues while still enabling rapid response to genuine controller failures.
Data Source
AI summary
A method of controlling an SDN system, an SDN sub-controller, and an SDN system is provided. The SDN controller sends a keepalive notification to the SDN switch and the SDN sub-controller. The SDN switch sends a switching request to the SDN sub-controller on condition that the keepalive notification cannot be received during a predetermined specific period. The SDN sub-controller starts to control a communication setting of the SDN switch on condition that the keepalive notification cannot be received during the specific period and that the switching request has been received.