NetFlow - what is a flow

NetFlow is a network management feature that allows us to track flows on our network. We can use this information to solve problems like bottlenecks, identify what applications are used, how much bandwidth they use etc.

A flow is a unidirectional sequence of packets that all share seven values which define a unique key for the flow:

  • Source IP address
  • Destination IP address
  • Source port number
  • Destination port number
  • Layer 3 protocol type
  • Type of service (ToS)
  • Input logical interface