Real world sflow vs netflow?

Harry Hoffman hhoffman at
Fri Jul 13 17:52:28 UTC 2012

Hi David,

I'm not sure that sflow is going to get your the granularity that you
are looking for. It's usually better to start more granular and then
aggregate into larger flows when you graph or reference for historic values.

Have you looked at other options, such as argus [1] to collect flow data
outside of the networking gear?

This way the networking gear can do what its primary job and flow
collection can happen elsewhere.

There's a whole argus community that discusses the information security
topics you're interested in and Carter, the guy who wrote all (?) of the
code is very responsive. Argus can also take in NetFlow flows from your
routers too.

There are obviously other tools available, that may work as well or
better, but argus is one I've been using with great success in a fairly
heavily trafficked environment.



On 07/13/2012 01:30 PM, David Hubbard wrote:
> Can anyone on or off list give me some real world
> thoughts on sflow vs netflow for border
> routers? (multi-homed, BGP, straight v4 & v6 only
> for web hosting, no mpls, vpns, vlans, etc.)
> Finding it hard to decipher the vendor version
> of the answer to that question.  We use
> netflow v9 currently but are considering hardware
> that would be sflow.  We don't use it for
> billing purposes, mostly for spotting malicious
> remote hosts doing things like scans, spotting
> traffic such as weird ports in use in either 
> direction that warrant further investigation,
> watching for ddos/dos destinations to act on
> mitigation, or investigating the nature of unusual
> levels of traffic on switch ports that set off
> alarms.  I'm concerned things like port scans,
> etc. won't be picked up by the NMS if fed by
> sflow due to the sampling nature, or similar
> concern if 500 ssh connections by the same remote
> host are sampled as 1 connection, etc.  Of course
> these concerns were put in my head by someone
> interested in me continuing to use equipment that
> happens to output netflow data, hence me wanting some
> real people answers. :-)
> Thanks!

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