OpenFlow Switch Link-Down for Controller Timeout Failover
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Solution Overview
Problem
In CD separation type networks, such as OpenFlow networks, communication troubles between internal switches and controllers lead to difficulties in detecting and managing external communication issues, resulting in suboptimal route control and increased costs due to inflexible network designs.
Innovation Solution
A communication route control system that allows for switching to a redundant route by performing a link-down of ports connected to external communication devices at internal switches when a communication timeout is detected, enabling the controller to reroute traffic through standby switches and external networks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the controller is separated from the network apparatus to enable intensive management and high flexibility, then the control flexibility and management efficiency are improved, but the reliability deteriorates when communication timeout occurs between the internal switch and controller
Solution Approach 1:
The patent applies preliminary action by having the internal switch pre-configure a link to a standby switch before any failure occurs. When communication timeout with the controller is detected, the internal switch can immediately activate the redundant route through the standby switch without waiting for controller intervention, thus maintaining reliability while preserving control flexibility.
Solution Approach 2:
The patent implements beforehand cushioning by establishing a redundant communication path through a standby switch in advance. This cushioning mechanism ensures that when the primary controller-switch communication fails, the system has a pre-prepared backup path to maintain operation, thereby compensating for the reliability weakness introduced by controller separation.
2Productivity
If the controller maintains continuous control over all switches to ensure optimal route management, then the route control efficiency is improved, but the device complexity increases when managing large-scale networks
Solution Approach 1:
The patent applies segmentation by dividing the network into segments with standby switches that can independently handle failover for their respective segments. This reduces the complexity of centralized controller management in large-scale networks while maintaining route control efficiency, as the controller only needs to manage the overall topology rather than every individual switch failure scenario.
Solution Approach 2:
The patent implements self-service by enabling internal switches to autonomously detect communication timeouts and automatically switch to redundant routes without requiring continuous controller intervention. This reduces the complexity of controller management while maintaining route control efficiency, as the switches serve themselves by making local failover decisions.
3Duration of action of stationary object
If the internal switch maintains connection to external communication devices to ensure continuous service, then the service continuity is improved, but the loss of information increases when communication timeout occurs with the controller
Solution Approach 1:
The patent applies the intermediary principle by introducing a standby switch as a mediator between the internal switch and the external communication devices. When communication timeout with the controller occurs, the standby switch acts as an intermediary that can maintain the connection to external devices while the route control information is preserved or recovered, thus maintaining service continuity without losing critical routing information.
Data Source
AI summary
On the OpenFlow network/normal network boundary, the route cannot be appropriately changed under a communication trouble with the controller. In this invention, the controller makes the route formed by internal switches optimal by updating the Flow table of each internal switch. Among internal switches, the internal switch A forms the optimal route with an external switch to become an active internal switch. The internal switch B forms a redundant route with the external switch to become a standby internal switch. When inability of the connection between the controller and the internal switch A is detected, the internal switch A performs a link-down of the port for connecting to the external switch. When the link-down of the port connecting to the internal switch A is detected, the external switch changes the route so that the traffic to the active internal switch A is transferred to the standby switch B.