Re: What does 95th %tile mean?

[Henry Yen <henry () AegisInfoSys com>]

On Mon, Apr 23, 2001 at 07:09:56AM -0400, Andrew Odlyzko wrote:
> First, while there have been many postings about 95th %tile
> pricing, nobody has said what that pricing actually is.  Well,
> here is an example of such pricing, downloaded from the UUNet
> page 2 years ago.  (I could not find current prices there on
> a quick scan.  Perhaps somebody else can post them, especially
> for higher bandwidth connections.)  Ignoring one-time start-up 
> fees, regular flat rate T-1 service was available from UUNet at 
> $2,495 per month.  The burstable rate (based on the 95th %tile 
> rating) was:
>
>                    T1 Usage Level            Burstable Service
>                                              Monthly Rate
>                    0 to 128 Kbps             $1,295
>                    128 Kbps to 256 Kbps      $1,895
>                    256 Kbps to 384 Kbps      $2,495
>                    384 Kbps to 512 Kbps      $2,750
>                    Over 512 Kbps             $3,000

current UUnet T-1 pricing (metro NYC area):

0-128K          $995
128K-256K       $1,395
256K-384K       $1,795
384K-512K       $1,895
> 512K           $2,095

flat-rate       $1,795

(local loop extra.  setup charge of $3,000 extra.  router extra.)

note that UUnet indicates they do not specifically compete on price. (duh.)
in the same area, i've gotten T-1 quotes as low as $500, plus loop.

> Note that even if the link is not used at all, you pay more than
> half the cost of a full T-1 connection.  (Hence some of the
> imaginative gaming schemes that have been proposed, involving
> rotating Web hosting traffic among a bunch of connections, are
> clear losers, as some posters have already noted.  It is less
> expensive to have a single unlimited service T-1 than two
> burstable one.)  Moreover, if your usage gets above a certain
> level, you pay more than for the full T-1.

the UUnet contract reads, "If Customer's sustained use level (95th percentile
traffic sampling rate) exceeds Customer's then-current burstable service
in two consecutive months, Customer's burstable service level may be upgraded
by UUNET and the monthly billing adjusted accordingly."  it doesn't specify
if this adjustment is retroactive (it doesn't seem so).  there's also
provision for downgrading, on similar terms.

> Yet another factor that comes in is that of discounts.  The
> prices listed above were the list prices.  I have been told by
> one member of this list that substantial discounts are common
> for full connections, but seldom for burstable ones, which makes
> the case against flat rate links even weaker.

any study on this issue should also include comparisons of fractional
circuit pricing, too.  although i've rarely (never?) seen a situation
where fractional makes financial sense (i.e., the frac prices were
typically only slightly less than full pricing), the fact that
you can quickly/instantly turn a couple of knobs and upgrade
to a higher fraction could be a factor, especially if you don't
intend to normally burst any higher than the fraction you're paying for.

-- 
Henry Yen                                       Aegis Information Systems, Inc.
Senior Systems Programmer                       Hicksville, New York