Forwarding Element Shadow Table for OpenFlow Traffic Reduction
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Solution Overview
Problem
Current OpenFlow networks face inefficiencies due to high communication traffic and processing burdens between forwarding elements and controllers, particularly when handling new packet flows and table misses, which can overwhelm the OpenFlow channel and require frequent reprogramming of flow rules.
Innovation Solution
Implementing a shadow table within the forwarding element to locally match and process packets, allowing for the installation of new flow rules without transmitting packets to the control plane, thereby reducing communication with the controller and offloading processing tasks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If packets are matched against flow tables in forwarding elements, then network security and quality of service are improved, but communication traffic between forwarding elements and controllers increases
Solution Approach 1:
The patent segments the flow table into two parts: a shadow table stored locally in the forwarding element and a main flow table stored in the controller. The shadow table contains a subset of flow rules that are frequently accessed or recently added, allowing the forwarding element to perform local matching without querying the controller for every packet, thus reducing communication traffic while maintaining security.
Solution Approach 2:
The patent implements preliminary action by pre-loading flow rules into the shadow table before they are needed for packet matching. When a new flow rule is added to the controller's flow table, it is proactively pushed to the forwarding element's shadow table in advance, so that subsequent packets matching this rule can be processed locally without controller intervention.
2Adaptability or versatility
If flow rules are frequently updated in response to packet matching, then network adaptability is improved, but controller processing burden increases
Solution Approach 1:
The patent extracts the function of flow rule installation from the controller and relocates it to the forwarding element. When a packet matches a rule in the shadow table, the forwarding element autonomously installs the corresponding flow rule in its main flow table without requiring controller processing, thus reducing the controller's processing burden while maintaining network adaptability.
Solution Approach 2:
The forwarding element performs self-service by autonomously managing its own flow table based on packets it receives and matches against the shadow table. The forwarding element can independently add, update, and remove flow rules based on local packet analysis and shadow table matches, without requiring continuous controller intervention for each flow rule update.
3Manufacturing precision
If all packet matching is performed by the controller, then flow table management accuracy is improved, but network efficiency decreases
Solution Approach 1:
The patent introduces a new dimension of operation by implementing a two-tier architecture where the shadow table operates at the forwarding element level for rapid local matching, while the main flow table operates at the controller level for centralized management. This dimensional separation allows accurate flow table management to be maintained at the controller while high-speed packet processing occurs at the forwarding element, resolving the trade-off between accuracy and efficiency.
Data Source
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AI summary
A method may be provided to operate a forwarding element in a forwarding plane of a network including the forwarding plane and a control plane. The method may include receiving a packet through an input/output port of the forwarding element and attempting to match the packet with a flow table of the forwarding element. Responsive to the packet missing a match with the flow table, the forwarding element may attempt to match the packet with a shadow table of the forwarding element. Responsive to the packet matching with the shadow table, a new flow rule may be installed in the flow table based on a matching shadow rule from the shadow table. Related forwarding elements are also discussed.