[156507] in North American Network Operators' Group
Re: IPv6 Ignorance
daemon@ATHENA.MIT.EDU (Owen DeLong)
Wed Sep 19 01:20:23 2012
From: Owen DeLong <owen@delong.com>
In-Reply-To: <2AF841AB78217140A2A394B2BB6D39C501128733@IDCPRDMBX1.ads.integratelecom.com>
Date: Tue, 18 Sep 2012 22:13:59 -0700
To: "Beeman, Davis" <Davis.Beeman@integratelecom.com>
Cc: "nanog@nanog.org" <nanog@nanog.org>
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
I won't dispute that, but let's look at some of the densest uses of it, =
factoring in the vertical aspects
as well...
Let's assume an 88 story sky scraper 1 city block square (based on an =
average of 17 city block/mile).
That's 96,465 sq. feet (8,961,918 sq. cm.) total building foot print.
Subtract roughly 1,000,000 sq. cm. for walls, power, elevators, risers, =
etc leaves us
with 7,961,918 sq. cm. per floor.
Figure in a building that large, you probably need 5 floors for =
generators, 8 floors for chiller plants,
and another 2 floors or more for other mechanical gives us a total of 73 =
datacenter floors max.
(Which I would argue is still unrealistic, but what the heck).
Subtract 1/3rds of the datacenter area for PDUs and CRAC units puts us =
at 5,307,945 sq. cm.
per floor.
FIguring a typical cabinet occupancy area + aisles of 2'x6' (small on =
the aisles, actually) gives us 12 sq. ft
per cabinet =3D 11,148 sq. cm. per cabinet so we get roughly 715 =
cabinets per floor (max) and let's assume
each 1U server holds 1000 virtual hosts at 42 servers per cabinet, =
that's 30,030 addresses per cabinet.
Multiplied by 75 floors, that's a building total of 2,252,250 total =
addresses needed. We haven't even
blown out a single /64 (and that's without allowing for the lower =
address density on routers, core switches,
etc.).
Let's assume we want to give a /64 to each server full of virtual hosts, =
we're still only taliking about 53,625
/64s, so the whole building can still be addressed within a /48 pretty =
easily (unless you think you have
more than 12,000 additional point-to-point/other =
administrative/infrastructure links within the building in
which case, you might need as much as a /47.)
In terms of total addresses per cm, 2,252,250 addresses spread over the =
building footprint of 8,961,918
sq. cm. is still only 0.25 addresses per sq. cm. so it falls well short =
of the proposed 2 addresses per
sq. cm.
To even achieve the suggested 2 addresses per sq. cm, you would need to =
make the building
704 stories tall and still dense-pack every possible sq. foot of the =
building with datacenter and
you'd have to put these kinds of buildings EVERYWHERE on earth, =
including over the oceans.
I'm willing to say that based on that math, there are more than enough =
addresses for virtually any
rational addressing scheme.
Owen
On Sep 18, 2012, at 09:01 , "Beeman, Davis" =
<Davis.Beeman@integratelecom.com> wrote:
> Orbits may not be important to this calculation, but just doing some =
quick head math, I believe large skyscrapers could already have close to =
this concentration of addresses, if you reduce them down to flat earth =
surface area. The point here is that breaking out the math based on the =
surface area of the earth is silly, as we do not utilize the surface of =
the earth in a flat manner...=20
>=20
> Davis Beeman=20
>=20
>=20
>> On Mon, Sep 17, 2012 at 11:27:04AM -0700, Owen DeLong wrote:
>>=20
>>> What technology are you planning to deploy that will consume more =
than 2 addresses per square cm?
>>=20
>> Easy. Think volume (as in: orbit), and think um^3 for a functional=20
>> computers ;)
>=20
> I meant real-world application.
>=20
> Orbits are limited due to the required combination of speed and =
altitude. There are a limited number of achievable altitudes and =
collision avoidance also creates interesting problems in time-slotting =
for orbits which are not geostationary.
>=20
> Geostationary orbits are currently limited to one object per degree of =
earth surface, and even at 4x that, you could give every satellite a /48 =
and still not burn through a /32.
>=20
> Owen
>=20
