Re: Configuration Parameters

From: Wanja Jansson (
Date: 11/27/02

  • Next message: Neil McKee: "Re: Configuration Parameters"

    Hi again,

    >What tool are you using to receive the sFlow packets and
    >report the results?

    First I use the sflowtool to convert the sflow into netflow and then i use
    CAIDA's cflowd to view the data through the arts++ dataviewers. The same I
    do with the netflow data I get from the NTOP nProbe, but here I already
    have the netflow format and can send it directly into the cflowd. In that
    way I get the same presentation of the data from both the probes and can
    compare the data

    >Multiplying by the configured sampling rate is only an
    >approximate way to scale up the results. The correct way to
    >do it is to multiply by the delta in the samplePool variable
    >divided by the number of samples. That way you will not be
    >affected by packet loss in transit or pseudo-random bias in
    >the random number generator.
    >For details, see the equations in "Packet Sampling Basics" on
    >the website.

    Ok, But then how come I get "good results" calculating the total number of
    packets when copying a big file on about 800 MB and when I do the same test
    with a file on 20MB, I do not get any correct number of bytes at all. Or is
    the probes just ment to give an overiwev of the traffic in the network and
    do not look so much in detail on each transmission?

    >When you say "nProbe" do you mean "NTop Probe"?

    Yes , the NTOP nProbe.


    Wanja Jansson

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