Network Controller Transition Protocol for Switch Rule Set Updates
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Solution Overview
Problem
In dynamic networks, route updates occur asynchronously, leading to unpredictable network behavior and pathological conditions, as switches update at different and unpredictable times, affecting packet routing.
Innovation Solution
A transition protocol implemented by a network controller ensures that all packets are handled by a single consistent set of rules during rule set changes, where switches forward packets to the controller if their next hop changes, and the controller forwards them according to the new rule set once all switches are updated.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If route updates occur asynchronously at each switch independently, then switches can update routing rules flexibly and adapt quickly to local changes, but network behavior becomes indeterminate and pathological conditions occur
Solution Approach 1:
The patent introduces a controller as an intermediary that coordinates route updates across the network. The controller receives update requests, determines the set of switches affected by each update, and orchestrates the timing of updates to ensure consistency. This mediator resolves the contradiction by providing centralized coordination that ensures predictable network behavior while still allowing flexible route changes.
Solution Approach 2:
The patent implements preliminary actions by having the controller determine the complete set of switches affected by a route update before actually applying the update. The controller calculates the transitive closure of affected switches and prepares the update plan in advance, ensuring that all necessary switches are updated in a coordinated manner. This preliminary planning prevents pathological conditions while maintaining adaptability.
2Stability of the object's composition
If all switches are updated simultaneously to a new rule set, then network consistency is maintained, but it is impossible to implement all updates instantaneously due to practical constraints
Solution Approach 1:
The patent segments the network into groups of switches based on their affectedness by route updates. Instead of treating all switches uniformly, the controller identifies and updates only the relevant subsets of switches in a coordinated sequence. This segmentation allows updates to be implemented efficiently across different time periods while maintaining consistency within each segment, resolving the contradiction between simultaneous updates and practical constraints.
Solution Approach 2:
The patent implements route updates in periodic phases rather than attempting a single simultaneous update. The controller orchestrates multiple update waves, where each wave updates a specific group of switches. This periodic approach maintains network consistency within each phase while accommodating the practical limitation that updates cannot be truly simultaneous across the entire network.
3Productivity
If switches maintain multiple rule sets during transition, then seamless updates can be performed, but switch resources are consumed by maintaining multiple rule sets simultaneously
Solution Approach 1:
The patent implements dynamic rule set management where switches transition from one rule set to another in a coordinated manner. The controller manages the timing and sequence of transitions, ensuring that switches dynamically switch between rule sets based on the update phase. This dynamic approach allows seamless transitions while minimizing the time that multiple rule sets coexist, thereby conserving switch memory resources.
Solution Approach 2:
The patent prepares for rule set transitions by having the controller determine the complete update plan before execution. The controller identifies all affected switches and the sequence of updates in advance, cushioning against the need for switches to maintain multiple rule sets for extended periods. This prior planning ensures that transitions are efficient and resource-consuming simultaneous maintenance of multiple rule sets is minimized.
Data Source
AI summary
A transition protocol is provided herein in which a first rule set for routing packets received by a group of switches during a first time period is to be updated to a second rule set. During a transition period, at least some switches in the group of switches route packets to a controller, while other switches in the group of switches route packets to a next hop that is unchanged by the change in the rule set. The controller forwards packets that are received from at least some of the switches in the group to a destination node each of the packets, as determined from the updated rule set.