SUMMARY - 95th percentile calculation

My thesis that I wanted to prove or disprove was that the
market seems to
have standardized how they calculate 95th percentile.  Years
ago if you
asked all your uplinks you'd get wildly different answers. 
Averages or max
values over days, weeks or months.  Rarely would two answers
jive.

But it appeared that most providers are now using 5 minute
averages as the 
value input over a billing month for 95th% calculation.  Was
this truly 
standard now?

The answer is yes.  All of our paid transit links use 5
minute averages, 
and all but one of the replies to my query here did too.

8 providers use 5 minute averages of 30 second counter
checks as the base
value calculated over the billing month.

2 providers use 5 minute averages of 1 minute counter checks
as the base
value calculated over the billing month.

8 providers use 5 minute implicit averages (a single counter
check) as the 
base value calculated over the billing month.*

1 provider uses the maximum value found in 5 minutes of 1
minute counter 
checks for the 5 minute value, and calculates that over the
billing month.

1 provider uses 5 minute implicit averages (a single counter
check) but
calculates that over a fixed 30 day month. (I didn't ask
what they did with
the extra days)

At first glance my tendancy would be to say that 20 answers
is hardly
authoritative, but the 30 second counters (first listed)
comprise 6 of the 
top US bit movers, and 2 of the largest bit pushers so I'm
satisfied with 
the results for my purposes.

* One very large bit mover that I know uses 32 bit counters
claimed to only
be checking every 5 minutes.  We're pushing enough to them
to rotate that
counter in that interval, so I actually disbelieve this
answer but I'm
reporting it as they said it.

-- 
Jo Rhett
senior geek
SVcolo : Silicon Valley Colocation

I'm not operationally involved at AT&T, but what I've
been told is that we track
5-minute samples in both directions, and do the 95th%
calculation on
all the samples,
as opposed to tracking 95% of inbound-only or outbound-only
or
max(in,out) samples.

On 2/27/06, Jo Rhett <jrhettsvcolo.com> wrote:
>
> My thesis that I wanted to prove or disprove was that
the market seems to
> have standardized how they calculate 95th percentile. 
Years ago if you
> asked all your uplinks you'd get wildly different
answers.  Averages or max
> values over days, weeks or months.  Rarely would two
answers jive.
>
> But it appeared that most providers are now using 5
minute averages as the
> value input over a billing month for 95th% calculation.
 Was this truly
> standard now?
>
> The answer is yes.  All of our paid transit links use 5
minute averages,
> and all but one of the replies to my query here did
too.
>
> 8 providers use 5 minute averages of 30 second counter
checks as the base
> value calculated over the billing month.
>
> 2 providers use 5 minute averages of 1 minute counter
checks as the base
> value calculated over the billing month.
>
> 8 providers use 5 minute implicit averages (a single
counter check) as the
> base value calculated over the billing month.*
>
> 1 provider uses the maximum value found in 5 minutes of
1 minute counter
> checks for the 5 minute value, and calculates that over
the billing month.
>
> 1 provider uses 5 minute implicit averages (a single
counter check) but
> calculates that over a fixed 30 day month. (I didn't
ask what they did with
> the extra days)
>
> At first glance my tendancy would be to say that 20
answers is hardly
> authoritative, but the 30 second counters (first
listed) comprise 6 of the
> top US bit movers, and 2 of the largest bit pushers so
I'm satisfied with
> the results for my purposes.
>
> * One very large bit mover that I know uses 32 bit
counters claimed to only
> be checking every 5 minutes.  We're pushing enough to
them to rotate that
> counter in that interval, so I actually disbelieve this
answer but I'm
> reporting it as they said it.
>
> --
> Jo Rhett
> senior geek
> SVcolo : Silicon Valley Colocation
>


--
----
             Thanks;     Bill

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