In-Band Forwarding Element Control via Remote Data-Plane Messages
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing forwarding elements are vulnerable to control plane processor failures and are costly due to the use of high-end processors, which also require additional expensive components like cooling systems.
Innovation Solution
A forwarding element configured through in-band data-plane messages from a remote controller, featuring configurable message-processing stages, storage queues, and a data-plane configurator that processes and stores configuration messages, ensuring reliable communication and reducing dependency on control plane processors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high-end control plane processors are used in forwarding elements, then processing capability and control functionality are improved, but cost and system complexity increase due to expensive processors and additional components like cooling systems
Solution Approach 1:
The control plane functionality is extracted from the forwarding element and placed in a separate remote controller. The forwarding element retains only the minimal control plane processor needed to handle local management interfaces, while all complex control processing is performed remotely. This separation eliminates the need for high-end processors and associated cooling systems in the forwarding element, directly resolving the contradiction between processing capability and system complexity.
Solution Approach 2:
A remote controller acts as an intermediary between the network management system and the forwarding element. This intermediary handles all complex control plane operations, allowing the forwarding element to use simple processors while maintaining full control functionality through the mediation of the remote controller. The intermediary pattern resolves the contradiction by externalizing the complex processing requirements.
2Ease of operation
If high-end control plane processors are used in forwarding elements, then control functionality is improved, but reliability decreases because control plane processor failures cause forwarding element failures
Solution Approach 1:
The control plane is extracted from the forwarding element and relocated to a separate remote controller. This physical and functional separation means that control plane processor failures in the remote controller do not directly cause forwarding element failures. The forwarding element can continue to forward traffic while the control plane is restored, significantly improving reliability while maintaining full control functionality.
Solution Approach 2:
The control plane and data plane are segmented into separate physical entities. The forwarding element contains the data plane with simple control plane processor, while the remote controller contains the complex control plane processor. This segmentation isolates failure domains, so that control plane failures do not propagate to the data plane, resolving the reliability issue while preserving control functionality.
3Device complexity
If in-band data-plane messages are used for configuration, then cost is reduced by eliminating high-end processors, but communication reliability must be ensured through additional validation mechanisms
Solution Approach 1:
The data plane performs preliminary validation actions on incoming configuration messages before processing them. Checksum verification, format validation, and authorization checks are performed in advance by the data plane, ensuring that only valid and authorized configuration messages are processed. This preliminary validation maintains communication reliability while allowing the use of simple processors.
Solution Approach 2:
The system implements feedback mechanisms where the data plane sends acknowledgments and status information back to the remote controller regarding configuration message processing. This feedback loop allows the remote controller to verify successful configuration application and retry failed operations, maintaining reliability despite the use of in-band data-plane messaging with simpler processors.
Data Source
AI summary
Some embodiments of the invention provide a forwarding element that can be configured through in-band data-plane messages from a remote controller that is a physically separate machine from the forwarding element. The forwarding element of some embodiments has data plane circuits that include several configurable message-processing stages, several storage queues, and a data-plane configurator. A set of one or more message-processing stages of the data plane are configured (1) to process configuration messages received by the data plane from the remote controller and (2) to store the configuration messages in a set of one or more storage queues. The data-plane configurator receives the configuration messages stored in the set of storage queues and configures one or more of the configurable message-processing stages based on configuration data in the configuration messages.