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North American Network Operators Group Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical Re: representativeness of flow data based on samples
### On Wed, 30 Jan 2002 14:02:30 -0500, Joe Abley <[email protected]> ### casually decided to expound upon [email protected] the following thoughts ### about "representativeness of flow data based on samples": JA> For example, if I am trying to rank the top traffic sinks for my JA> network beyond an attached peer (i.e. an ordinal rather than cardinal JA> measurement), will I get different answers if I use a sampling rate JA> of 1:1000 compared to 1:50, given a statistically "long enough" JA> measurement period? I suspect that it will just determine the smoothness of your statistics over the long run which I assume is what you're interested in. I guess it will depend on the ballpark expected packet flow. One might ask the question of "how close do things seem/need to be?" One has to assume the sampling run time is bigger than the sampling rate by a certain order of magnitude because the amount of sampling error can be predicted as the square root of the number of samples. So what does a per-sample loss mean to you? And how much error can you tolerate? Figure that out and you can narrow in on an appropriate sampling period. -- /*===================[ Jake Khuon <[email protected]> ]======================+ | Packet Plumber, Network Engineers /| / [~ [~ |) | | --------------- | | for Effective Bandwidth Utilisation / |/ [_ [_ |) |_| N E T W O R K S | +=========================================================================*/
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