I've got 15+ Cisco ISR 4000's (a mix of 4331s and 4551s) in our network and when trying to setup Netflow to PRTG, It seems that when I hit 5 interfaces that need to be monitored, there is always 1 that won't come up in PRTG and that doesn't send data. I've got all 5 ports setup with the same config (using separate ports for each interface we want to monitor) and 4 of the 5 will come up, or they will all come up and then 1 will go down within PRTG. If I clear the counters on the flow stats, it will sit at 0, not sending any packets. Below is an example:
router#show flow exporter NetFlow-to-PRTG-gig_0_0_0.800 stat
Flow Exporter NetFlow-to-PRTG-gig_0_0_0.800:
Packet send statistics (last cleared 00:24:32 ago):
Successfully sent: 0 (0 bytes)
Client send statistics:
Client: Flow Monitor NetFlow-Monitor
Records added: 0
Bytes added: 0
My per-interface exporter looks like this for all interfaces, except each one is sending on a different port:
flow exporter NetFlow-to-PRTG-gig_0_0_0.800
description Exports NetFlow to PRTG
destination 10.81.X.X
source GigabitEthernet0/0/0.200
transport udp 2058
template data timeout 120
It seems like once I hit netflow for 5 ports, then one of them doesn't work however its not consistent across all routers. Some routers will have all 5 monitored in PRTG, others will only allow 4 to come up. We have a mix of 4331 and 4551s however it doesn't seem to matter the model or code level. It happens on some and not the others. I'm at a complete loss as to what is going on and why a port will send netflow packets and then suddenly stop.
