Can Netflow collect statistics on layer2 interfaces?

cchughes · ‎01-02-2009

I have enabled netflow on a 6513 running 12.2(33)SXH2a. Right now it is collecting statistics for layer3 interfaces only. Can Netflow be configured to collect statistics for layer2 interfaces?

Collin Clark · ‎01-02-2009

Nope.

Hope that helps.

letsgomets · ‎01-02-2009

Curious... what type of information are you trying to capture in netflow on a L2 interface?

cchughes · ‎01-02-2009

I'm concerned about seeing server to server flows on the same subnet/vlan. Will a L3 vlan interface do the trick?

Richard Burts · ‎01-03-2009

Chris

If the server to server flows are on the same subnet/vlan then the servers communicate directly with each other - from a layer 3 perspective. (frames do come in one layer 2 switch port and exit another layer 2 switchport - so in a layer 2 perspective the 6500 does see them) From a layer 3 perspective the 6500 does not see that traffic. And NetFlow reflects what the router/switch sees at layer 3. So I do not believe that it is possible to see what you want with NetFlow.

HTH

Rick

HTH

Rick

cchughes · ‎01-04-2009

Thanks Rick, That clears it up for me.

bergmann · ‎03-11-2009

Hi,

on a Cat6500 (Sup720) it is possible to monitor L2 traffic with netflow.

See http://www.cisco.com/en/US/docs/switches/lan/catalyst6500/ios/12.2SX/configuration/guide/netflow.html#wp1157805 (Enabling NetFlow for Ingress-Bridged IP Traffic) for details.