In-Band Forwarding Element Configuration Without a Control Processor
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Solution Overview
Problem
Existing forwarding elements are prone to failure due to control plane processor failures and are costly, requiring expensive high-end processors and 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 by checking for message corruption and using checksums and CRC operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a control plane processor is used to configure the forwarding element, then the forwarding element can be configured and managed, but the system becomes prone to failure and requires expensive high-end processors and 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 data plane circuits, which process configuration messages received from the remote controller through in-band data-plane messaging. This separation eliminates the need for expensive control plane processors and cooling systems in the forwarding element while maintaining configuration capabilities.
Solution Approach 2:
Configuration messages serve as an intermediary mechanism between the remote controller and the data plane circuits. These messages carry configuration data through the data-plane communication path, allowing the forwarding element to be configured without requiring a local control plane processor. The message-processing stages and data-plane configurator act as intermediaries to process and apply configuration data.
2Ease of operation
If high-end processors and cooling systems are used in the forwarding element, then configuration and management capabilities are ensured, but the cost and expense increase significantly
Solution Approach 1:
The expensive control plane processor and cooling system components are extracted from the forwarding element and relocated to a separate remote controller. The forwarding element uses only simple data plane circuits that can process configuration messages, dramatically reducing hardware costs while preserving configuration capabilities through in-band messaging.
Solution Approach 2:
The data plane circuits are designed to perform multiple functions: they handle both data forwarding operations and configuration message processing. The message-processing stages can process both data messages and configuration messages, and the data-plane configurator can configure the data plane circuits based on configuration data received from the remote controller, eliminating the need for dedicated control plane hardware.
3Adaptability or versatility
If control plane processors are used, then the forwarding element can receive and process configuration parameters, but the system becomes vulnerable to failures that cause forwarding element failures
Solution Approach 1:
The system is segmented into two independent components: a remote controller that generates configuration messages and a forwarding element that processes them. This segmentation isolates the forwarding element from control plane failures, as the data plane circuits can continue to operate using previously configured parameters even if the remote controller experiences issues.
Solution Approach 2:
The data plane circuits are designed to be self-configuring through the in-band messaging mechanism. The configurable message-processing stages automatically process configuration messages from the remote controller, and the data-plane configurator automatically applies configuration data to configure the data plane circuits, enabling the system to maintain operation with minimal external control.
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.