North American Network Operators Group

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Re: Interesting netflow entry

  • From: Bill Nash
  • Date: Tue Feb 07 14:21:54 2006

On Tue, 7 Feb 2006, Christopher L. Morrow wrote:
Are you sure you're getting everything?
he did previously state he was only using about 120mbps... and it'd depend
upon his/your sample rates as well...
Missed that part. Even so, 120mbps of actual usage, I would expect to see a higher volume. Sampling would definitely bring this down a bit, but for a volume that small, why bother sampling? You'll miss too much.

One problem I had while checking out various packages, flow-tools specifically, is that some can't handle differing flow versions. Also, flow generation from a routing-capable 6509 is configured in two different places, so the potential to lose flow traffic due to poor documentation (of both the collector and the generator) definitely exists. Flow-tools picks which version it processes based on the version of the first flow packet it receives, and then discards all else.

- billn