Command Reference, Cisco Ios Xe Everest 16.5.1A (Catalyst 3650 Switches - Cisco Catalyst 3650 series Command Reference Manual

The interface that you configure as the source interface must have an IP address configured, and it must
Caution
be up.
When a transient outage occurs on the interface that you configured with the source command, the Flexible
Tip
NetFlow exporter reverts to the default behavior of using the IP address of the interface over which the
datagrams are being transmitted as the source IP address for the datagrams. To avoid this problem, use a
loopback interface as the source interface because loopback interfaces are not subject to the transient
outages that can occur on physical interfaces.
To return this command to its default settings, use the no source or default source flow exporter configuration
command.
Examples
The following example shows how to configure Flexible NetFlow to use a loopback interface as the source
interface for NetFlow traffic:
Device(config)# flow exporter FLOW-EXPORTER-1
Device(config-flow-exporter)# source loopback 0
interface into any access lists that you create for permitting Flexible NetFlow traffic. Creating and
maintaining access lists for permitting Flexible NetFlow traffic from known sources and blocking it
from unknown sources is easier when you limit the source IP address for Flexible NetFlow datagrams
to a single IP address for each device that is exporting Flexible NetFlow traffic.

Command Reference, Cisco IOS XE Everest 16.5.1a (Catalyst 3650 Switches)

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