I've configured Flexible NetFlow (FNF) in a Cisco ASR1K router and sourced it from GigabitEthernet0 (Mgmt-intf), which is the default out-of-band management interface. I wasn't getting any NetFlow statistics in the collector server and found out in this Cisco link that FNF export isn't supported in the management port (below is a snippet). You'll notice in the show flow exporter statistics indicated a "failed to send" flow.
Restrictions for Flexible NetFlow
The following are restrictions for Flexible NetFlow:
Flexible NetFlow export is not supported on the Ethernet management port, Gi0/0.
ASR1K#show flow exporter statistics
Flow Exporter MyNetflow:
Packet send statistics (last cleared 00:00:05 ago):
Successfully sent: 0 (0 bytes)
Reason not given: 49 (64052 bytes)
Client send statistics:
Client: Option options application-name
Records added: 0
Bytes added: 0
Client: Option options application-attributes
Records added: 0
Bytes added: 0
Client: Flow Monitor MyNetflow
Records added: 1138
- failed to send: 1138
Bytes added: 62590
- failed to send: 62590
So I used a different source interface (sub-interface) and VRF which can still reach the NetFlow collector server. Notice the "failed to send" flows had disappeared.
ASR1K#show flow exporter statistics
Flow Exporter MyNetflow:
Packet send statistics (last cleared 00:01:30 ago):
Successfully sent: 2422 (3292436 bytes)
Client send statistics:
Client: Option options application-name
Records added: 2252
- sent: 2252
Bytes added: 186916
- sent: 186916
Client: Option options application-attributes
Records added: 0
Bytes added: 0
Client: Flow Monitor MysNetflow
Records added: 55823
- sent: 55823
Bytes added: 3070265
- sent: 3070265
