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Flexible netflow kills performance

Hi there!

We got a WS-C6506-E with Supervisor Engine 2T 10GE. I'm trying to export flows for analysis (I was already doing this in our previous switch with supervisor 720 with no problems).

When I activate flow in just one interface the bandwidth drops really bad (iperf show 138Mbits/sec). Without netflow we got 931Mbits/sec.


Cisco IOS Software, s2t54 Software (s2t54-IPBASEK9-M), Version 15.1(1)SY, RELEASE SOFTWARE (fc2)

Netflow config:

flow exporter FlowExporter1

  destination X.X.X.X

  source Vlan1

  transport udp 9090

  export-protocol netflow-v5



flow monitor FlowMonitor1

  exporter FlowExporter1

  record platform-original ipv4 full


interface Vlan1

  description NETWORK1

  ip address Y.Y.Y.Y

  ip access-group trafficNetExtUseIn in

  ip access-group trafficNetExtUseOut out

  ip helper-address H.H.H.H

  ip nat outside

  ip flow monitor FlowMonitor1 input

So the "ip flow monitor FlowMonitor1 input" command kills the bandwidth. Removing it, restores it.

We don't have so many flows (usualy range is 4000-6000):

#sh platform flow ip count
Number of netflow entry is 4586

Any ideas?

Best regards,


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