SDN Controller Flow Table Rule Prioritization for Communication Disruption
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Solution Overview
Problem
In software-defined networks (SDNs), communication disruptions between the SDN controller and network devices can lead to undesired forwarding behavior due to the inability to receive new instructions, resulting in continued execution of outdated rules.
Innovation Solution
The SDN controller generates and implements first and second flow table rules with different priority and timeout values, ensuring that when communication is active, the first behavior is followed, and upon disruption, the second behavior is activated, allowing for adaptive forwarding even during communication failures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the SDN controller continuously updates flow table rules to maintain optimal forwarding behavior, then forwarding performance is improved, but during communication disruptions the network device continues executing outdated rules leading to undesired forwarding behavior
Solution Approach 1:
The SDN controller pre-configures multiple flow table rules including a primary rule with higher priority and shorter timeout, and a secondary rule with lower priority and longer timeout. These rules are prepared in advance so that when communication disruption occurs, the secondary rule automatically becomes effective, providing failover capability without requiring real-time controller intervention.
Solution Approach 2:
The patent changes key parameters of flow table rules including priority values and timeout values. The primary rule has higher priority and shorter timeout for normal operation, while the secondary rule has lower priority and longer timeout for failover. This parameter variation allows the system to adapt forwarding behavior based on communication status between the controller and network device.
2Measurement precision
If the network device waits for new instructions from the SDN controller during communication disruption, then forwarding accuracy is maintained, but network traffic flow is blocked
Solution Approach 1:
The network device is pre-programmed with multiple flow table rules that include fallback forwarding behavior. When communication with the SDN controller is disrupted, the device can immediately execute the secondary rule to maintain traffic flow, rather than waiting for new instructions. This preliminary configuration enables autonomous operation during controller unavailability.
Solution Approach 2:
The network device is empowered to autonomously select and execute appropriate flow table rules based on its own determination of controller communication status. The device monitors communication health and automatically switches between primary and secondary forwarding rules without requiring continuous controller directives, enabling self-service operation during disruptions.
3Duration of action of stationary object
If the SDN controller uses a single flow table rule with long timeout to ensure continuous forwarding, then network availability is improved, but the ability to implement updated forwarding policies is reduced
Solution Approach 1:
The patent segments the forwarding control into multiple flow table rules with different characteristics. Instead of using a single long timeout rule, the system divides control into a primary rule with shorter timeout for policy updates and a secondary rule with longer timeout for continuity. This segmentation allows both frequent policy updates and continuous forwarding to coexist.
Solution Approach 2:
The SDN controller periodically refreshes the primary flow table rule with shorter timeout during normal operation, enabling regular policy updates. The periodic refresh mechanism ensures that forwarding policies can be updated while maintaining continuous network operation, as the controller can reissue updated rules before the timeout expires.
Data Source
AI summary
In an example, a method is disclosed for implementing forwarding behavior based on communication activity between an SDN controller and a network device. The method includes generating, for the network device, a first flow table rule to implement first forwarding behavior for a network flow if communication to the SDN controller is active. The first flow table rule comprises match criteria for matching to the network flow, a first timeout value, and a first priority value. The method also includes generating, for the network device, a second flow table rule to implement second forwarding behavior for the network flow if communication to the SDN controller is not active. The second flow table rule comprises match criteria for matching to the network flow, a second timeout value, and a second priority value. The method further includes instructing the network device to implement the first and second flow table rules.