Definition of flows, conversations and sessions

Q. What is the difference between a flow, a conversation, and a session?

A. They're similar, but slightly different:

* A flow is a uni-directional transfer between a pair of (IP Address, Port) using the same layer-3 protocol, type of service, and input interface.
* In InterMapper Flows, a session is a bi-directional transfer between a pair of (IP Address, Port). It is the sum of the flow from A to B, plus the flow from B back to A.
* Other NetFlow products define a conversation different ways, either as a session, in the InterMapper Flows sense, or as a uni-directional flow.