Glossary
What is NetFlow?
NetFlow is a Cisco protocol that lets a network manager get insight into the kind of traffic flowing on the network, and which computer(s) are sending it. NetFlow exporters (generally routers and switches) send information about the flows passing through them to a NetFlow collector for storage and analysis.
What is a NetFlow Exporter? What is a NetFlow Collector?
A NetFlow exporter is a router, switch, or piece of software that summarizes information about traffic flowing on a network/interface and exports the data to another computer — a NetFlow collector to be saved and analyzed.
What is a flow?
A flow is a measure of data transferred between two particular hosts. It consists of all the traffic for a period of time that has these same characteristics:
- Same Source IP address and port
- Same Destination IP address and port
- Same layer-3 protocol type (TCP, UDP, ICMP, etc.)
- Same ToS (type of service)
- Same input logical interface (e.g., ifIndex)
What is the difference between a flow, a conversation, and a session?
They're similar, but slightly different:
- As noted above, 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.
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