|
North American Network Operators Group Date Prev | Date Next | Date Index | Thread Index | Author Index | Historical Re: 95th Percentile again (was RE: C&W Peering Problem?)
On Sat, Jun 02, 2001 at 11:17:48PM -0400, Richard A. Steenbergen wrote: > There are only two ways you can poll the rate, either you poll a "rate" > value maintained on the device, or you poll a difference in bytes divide > by the length of time between samples to calculate a rate. Either way, if > the device does not support polling of the "interface" in question you are > pretty screwed. Not necessarily; you just have to find other ways of measuring, as we did, to good effect. > No matter how you stack it, if you miss a rate sample there is no way to > go back and get the data again. You either discard it and lose the ability > to bill the customer for it (which demands high availability polling > systems), or you make up a number and hope the customer doesn't notice. No -- there is no need to do that. You don't need a sample for every single five-minute interval during the month to produce a meaningful 95%ile measurement for the month; you just need a representative sample population. You increase the chances of your sample population being representative if you consider lots of samples, but dropping one or two does not mean you lose revenue. > Volume polling does not suffer from this problem. It does, if you don't have per-customer interface counters. You need to count every packet using some other method, and if you can't count packets, you can't bill for them. Joe
|