Terminology

Stateful Flow Management

Platform
Napatech SmartNIC
Content Type
User Guide
Capture Software Version
Link™ Capture Software 12.8

There are a number of specific terms to understand when using the Napatech stateful flow management.

Terminology

Term Explanation
Actions Actions exist both in the SmartNIC and in the application. Actions apply the rule that has been defined for processing that particular flow. The most common actions in the SmartNIC are forwarding a frame to a specific stream or dropping a frame. Refer to Flow Classification and Actions.
Fast path The fast path is where all identified flows are handled.
Flow A sequence of frames carrying information between two hosts where frames contain common header fields. Flow definition is dependent on user requirements. See Defining Flows for more information about how to define flows.
Flow info record A record that contains flow information which is generated at flow unlearning. See API: Read Flow Info of an Unlearned Flow.
Flow learning Adding a flow to flow tables. When unknown flows are received, the application writes the flows to the SmartNIC flow table and in the host flow table. See API: Learn a Flow.
Flow manager There is a flow manager both in the SmartNIC and in the application. The SmartNIC flow manager looks up the flow. If there is no match, the SmartNIC passes it to the application flow manager.
Flow status record A record that contains information about the flow-learning result, for example, whether learning of a flow is successful. See API: Read Flow Learn/Unlearn Result.
Flow stream A stream type which learns new flows, unlearns existing flows and receives flow info records at flow unlearning.
Flow scrubber The flow scrubber in the SmartNIC reads the SmartNIC flow table and times out inactive flows.
Flow table A flow table contains flow information. There is a flow table both in the SmartNIC and in the host.
Flow unlearning Deleting a flow from flow tables. A flow can be unlearned in three ways: at TCP termination, timeout or manually by the application. See Flow unlearning.
Hit The flow is found in the flow table.
Missed The flow is not found in the flow table.
Slow path The slow path is where all unknown flows are handled.
Unhandled The SmartNIC may not be able to look up the flow of received frames, for example, in rare situations under high traffic load. These unhandled frames can be delivered to the application for further processing.