[88898] in North American Network Operators' Group
Re: How do you (not how do I) calculate 95th percentile?
daemon@ATHENA.MIT.EDU (Warren Kumari)
Wed Feb 22 17:10:31 2006
In-Reply-To: <Pine.WNT.4.62.0602221513430.576@vanadium.hq.nac.net>
Cc: Jo Rhett <jrhett@svcolo.com>, nanog@merit.edu
From: Warren Kumari <warren@kumari.net>
Date: Wed, 22 Feb 2006 14:10:11 -0800
To: Alex Rubenstein <alex@nac.net>
Errors-To: owner-nanog@merit.edu
Doh! You are 100% correct.
I didn't take into account the fact that the counters are if(In|Out)
*Octets* and NOT if(in/Out)*Bits*.
The point is that 64-bit counters are not likely to roll :-)
Warren
On Feb 22, 2006, at 12:24 PM, Alex Rubenstein wrote:
>
>
> (I did this fast, and, who knows; I could be off my an order or two
> of magnitude)
>
>> Most people are using 64 bit counters. This avoids the wrapping
>> problem (assuming you don't have 100GE and poll more then once
>> every 5 years :-)).
>
> 2^64 is 18,446,744,073,709,551,616 bytes.
>
> 100 GE (100,000,000,000 bits/sec) is 12,500,000,000 bytes/sec.
>
> It would take 1,475,739,525 seconds, or 46.79 years for a counter
> wrap.
>
>
> --
> Alex Rubenstein, AR97, K2AHR, alex@nac.net, latency, Al Reuben
> Net Access Corporation, 800-NET-ME-36, http://www.nac.net
>
>
