What is a Flow?

Stateful Flow Management

Platform
Napatech SmartNIC
Content Type
User Guide
Capture Software Version
Link™ Capture Software 12.6

The definition of a flow is relatively fluid, and Napatech provides support for many variants.

Flow definitions

A flow can be described by any of these definitions:
  • A sequence of packets from a source to a destination (host, multicast group or broadcast domain)
  • An artificial, logical equivalent to a call or connection
  • A sequence of packets sent from a particular source to a particular unicast, anycast or multicast destination that the source desires to label as a flow. A flow can consist of all packets in a specific transport connection or media stream. A flow is not necessarily mapped 1-to-1 to a transport connection
  • A set of IP packets passing an observation point in the network during a certain time interval

Flow examples

Napatech stateful flow management supports flows that are defined in many ways, including subsets and groups of flows. These are examples of some of the supported flows:
  • 5-tuple flow (source IP, destination IP, source port, destination port, protocol are the most common parameters for flow identification) or similar (4-tuple, 2-tuple)
  • Subset of a flow (for example, 5-tuple/2-tuple and VLAN tag)
  • Groups of flows (for example, layer-2 flow: All packets between two MAC addresses)

This is an example of a 5-tuple flow:


Page-1 Sheet.27 Sheet.25 Sheet.1 Dest. MAC Dest. MAC Sheet.2 Src. MAC Src. MAC Sheet.3 Len Len Sheet.4 IP header IP header Sheet.5 Src. IP Src. IP Sheet.6 Dest.IP Dest.IP Sheet.7 Data Data Sheet.8 CRC CRC Sheet.9 Options Options Sheet.10 Data Data Sheet.11 Sheet.12 Sheet.13 Src Port SrcPort Sheet.14 DestPort DestPort Sheet.15 TCP Header TCP Header Sheet.17 Options Options Sheet.18 Data Data Sheet.19 Src Port SrcPort Sheet.20 DestPort DestPort Sheet.21 UDP Header UDP Header Sheet.23 Data Data Sheet.24 Sheet.26 Sheet.29 Src. IP Src. IP Sheet.30 Dest.IP Dest.IP Sheet.31 Src Port SrcPort Sheet.32 DestPort DestPort Sheet.33 Prot Prot Sheet.34 Sheet.35 Sheet.36 Sheet.37 Sheet.38 Sheet.39 Flow info extract: Flow info extract: Sheet.40 Sheet.41

This is an example of an alternative flow:


Page-1 Sheet.27 Sheet.25 Sheet.1 Dest. MAC Dest. MAC Sheet.2 Src. MAC Src. MAC Sheet.3 Len Len Sheet.4 IP header IP header Sheet.5 Src. IP Src. IP Sheet.6 Dest.IP Dest.IP Sheet.7 Data Data Sheet.8 CRC CRC Sheet.9 Options Options Sheet.10 Data Data Sheet.11 Sheet.12 Sheet.13 Src Port SrcPort Sheet.14 DestPort DestPort Sheet.15 TCP Header TCP Header Sheet.17 Options Options Sheet.18 Data Data Sheet.19 Src Port SrcPort Sheet.20 DestPort DestPort Sheet.21 UDP Header UDP Header Sheet.23 Data Data Sheet.24 Sheet.26 Sheet.34 Sheet.39 Alternative flow info extract 1: Alternative flow info extract 1: Sheet.42 Alternative flow info extract 2: Alternative flow info extract 2: Sheet.43 Dest. MAC Dest. MAC Sheet.44 Src. MAC Src. MAC Sheet.45 Sheet.46 Src. IP Src. IP Sheet.47 Dest.IP Dest.IP Sheet.48 VLAN 1 VLAN 1 Sheet.49 VLAN 2 VLAN 2 Sheet.50 VLAN 1 VLAN 1 Sheet.51 VLAN 2 VLAN 2 Sheet.52 Sheet.53 Sheet.54 Sheet.55