Netflow; Information About Netflow - Cisco Nexus 1000V Troubleshooting Manual

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NetFlow

This chapter describes how to identify and resolve problems that relate to Netflow.
This chapter includes the following sections:
• Information About NetFlow, page 14-1
• NetFlow Troubleshooting Commands, page 14-2
• Common NetFlow Problems, page 14-3

Information About NetFlow

NetFlow is a technology that lets you evaluate IP traffic and understand how and where it flows. NetFlow
gathers data that can be used in accounting, network monitoring, and network planning.
A flow is a one-directional stream of packets that arrives on a source interface (or sub-interface),
matching a set of criteria. All packets with the same source/destination IP address, source/destination
ports, protocol interface and class of service are grouped into a flow and then packets and bytes are
tallied. This condenses a large amount of network information into a database called the NetFlow cache.
You create a flow by defining the criteria it gathers. Flow information tells you the following:
Source address tells you who is originating the traffic.
•
Destination address tells who is receiving the traffic.
•
Ports characterize the application using the traffic.
•
Class of service examines the priority of the traffic.
•
• The device interface tells how traffic is being used by the network device.
• Tallied packets and bytes show the amount of traffic.
A flow record defines the information that NetFlow gathers, such as packets in the flow and the types of
counters gathered per flow. You can define new flow records or use the pre-defined Nexus 1000V flow
record.
For detailed information about configuring NetFlow, see the Cisco Nexus 1000V System Management
Configuration Guide, Release 4.2(1)SV2(1.1).
OL-28795-01
C H A P T E R
Cisco Nexus 1000V Troubleshooting Guide, Release 4.2(1)SV2(2.1)
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14-1