The Source IP address of BAS FLOW LOG UDP packet.
By default, the source IP address of the UDP packet
is the IP address of the interface through which the
router outputs the user log packet.
On the user log server side, the source of log
information can be located rapidly through identifying
the source IP address of the log. You are recommended
to configure a loopback address or router ID to function
as the source IP address of the UDP packet.