Hi Vijay,
NetFlow configuration is often only "Try and Error".
I guess, you have the same netflow configuration at the "good" and the "bad" routers.
Could you trace e.g. with WireShark directly on your server the communication with the (bad) routers for a longer time?
If yes, do you see any netflow trafic?
If not: - Perhaps you have to configure a source Interface (e.g. "Loopback3") for the flow exporter or a "VRF".
- Is there no "evil" Firewall in the communication patch?
- Try it with other interfaces.
- ?
If yes, but NFA says "No" or sees only a few uninteresting packets, then check your flow record definitions and try something.
(If you are not very familiar with WireShark: To make your netflow trace readable, you to decode it as "CLFOW".)
As promised: Here is our configuration example from a IOS XE device:
flow record COMM_Input
match datalink dot1q vlan input
match ipv4 tos
match ipv4 protocol
match ipv4 source address
match ipv4 destination address
match transport source-port
match transport destination-port
match interface input
collect transport tcp flags
collect counter bytes long
collect counter packets long
collect timestamp absolute first
collect timestamp absolute last
!
!
flow record COMM_Output
match datalink dot1q vlan output
match ipv4 tos
match ipv4 protocol
match ipv4 source address
match ipv4 destination address
match transport source-port
match transport destination-port
match interface output
collect transport tcp flags
collect counter bytes long
collect counter packets long
collect timestamp absolute first
collect timestamp absolute last
!
!
flow exporter SERVER1
destination 1.2.3.4 vrf abcd
source Loopback3
transport udp 9995
!
!
flow monitor COMM_Input
exporter Server1
cache timeout active 60
record COMM_Input
!
!
flow monitor COMM_Output
exporter Server1
cache timeout active 60
record COMM_Output
!
Regards, Frank