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Netflow from Nexus 7700

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Hi folks,

I have opened case PAE1093045 regarding this issue, but I figured I would post here in case other folks are having this issue in the future.

I am working on configuring Netflow on a Nexus 7700 core router. The configuration from the router is as followed:

!Command: show running-config netflow !Time: Mon Sep 24 11:49:54 2018

version 6.2(16) feature netflow

flow timeout 30 flow exporter PRTG destination 10.20.32.114 transport udp 9991 source Ethernet5/16 version 9 flow record PRTG match ipv4 source address match ipv4 destination address match ip protocol match ip tos match transport source-port match transport destination-port collect transport tcp flags collect counter packets collect flow sampler id collect ip version sampler PRTGSampler mode 1 out-of 128 flow monitor PRTGMONITOR record PRTG exporter PRTG

I have successfully tested this configuration on the PRTG using the Netflow tester application and I do see traffic that is being decoded all the way through. In addition, I am seeing Wireshark logs recorded from the PRTG server itself and the Netflow traffic is showing up.

However, my Netflow v9 sensor on PRTG continues to report that it has not received any data since startup.

Any ideas at this point would be greatly appreciated!

cisco netflow netflow-v9

Created on Sep 24, 2018 4:13:59 PM by  t3rebello (10) 1



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It's a known issue, please update to 18.3.44.2054 in order to have this resolved :)


PRTG Scheduler | PRTGapi | Feature Requests | WMI Issues | SNMP Issues

Kind regards,
Stephan Linke, Tech Support Team

Created on Sep 24, 2018 7:03:04 PM by  Stephan Linke [Paessler Support]



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Hello again Stephan,

I have updated to 18.3.44.2054 and the issue persists. The tester is not still running. Netflow on the target host has been disabled and re-enabled.

Wireshark PCAP's are showing that the Netflow traffic is making it into the server still. I am noticing that the template takes quite some time to be received when I begin a PCAP, but I suspect that this is not the issue because from what I understand, templates are only sent out by the target host every half hour by default.

Created on Sep 25, 2018 2:50:32 PM by  t3rebello (10) 1



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@t3rebello Please try to set the active flow timeout to 0 in order to avoid any timeout related issues if the processing of the templates takes a while. Let me know if it worked. If not, please open up a support request with probe status files :)

edit welp, you already did to which I already responded xD We'll keep it in the ticket from here on.


PRTG Scheduler | PRTGapi | Feature Requests | WMI Issues | SNMP Issues

Kind regards,
Stephan Linke, Tech Support Team

Created on Sep 26, 2018 8:12:02 AM by  Stephan Linke [Paessler Support]

Last change on Sep 26, 2018 8:13:38 AM by  Stephan Linke [Paessler Support]



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That works for me!

So the latest update is that I have it currently working. I am not sure what change did it, but I am happy with it. My current settings have the Active Flow on PRTG configured as 1 minute greater than the timeout, as PRTG documentation stated.

I am seeing 96% of my traffic come in as "Various" traffic, which will be my next hurdle, but Netflow itself is looking okay.

I will be deploying it to five other core devices shortly and will certainly post here if I have any issues.

Created on Sep 26, 2018 5:31:24 PM by  t3rebello (10) 1



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Nice :)


PRTG Scheduler | PRTGapi | Feature Requests | WMI Issues | SNMP Issues

Kind regards,
Stephan Linke, Tech Support Team

Created on Sep 27, 2018 6:45:33 AM by  Stephan Linke [Paessler Support]



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I have configured all 6 cores without any further issues.

For any other folks having the same issue as me, I encourage you to follow the troubleshooting steps we did above.

Update to 18.3.44.2054, ensure the NetFlow traffic is making it over to PRTG by running WireShark, and set your Active Flow to be 1 minute greater than the configuration on your Nexus core. Be sure to pay attention to the difference in units!

"flow timeout active 60" on the Nexus core means 60 SECONDS, not minutes, whereas PRTG is assigned to a value of 2 (MINUTES).

Cheers!

Created on Sep 27, 2018 10:54:54 PM by  t3rebello (10) 1



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