[ppml] 2005-1:Business Need for PI Assignments

Leo Bicknell bicknell at ufp.org
Mon Apr 25 12:45:16 EDT 2005

In a message written on Mon, Apr 25, 2005 at 04:31:42PM +0100, Michael.Dillon at radianz.com wrote:
> The question of waste has to do with the environment you are in, the sources
> of supply, and the difficulty of obtaining a resource. IPv6 addresses may

Your analogy here holds more water than you might think.

Water, like IPv6 addresses, is abundant.

Drinkable water, like usable IPv6 addresses, is not.

Using a /64 for a "LAN" is like dumping raw sewage into the water
and then wondering why it's contaminated.  2^32 times more than the
entire existing address space, for a single LAN.  When you dump in
pollution, you prevent those downstream from using the water to
drink.  Similarly, when you number a lan with a /64 you prevent
other network users from using any of those addresses, even though
you may only have 50,000 or 1,000,000 devices on your local LAN.

Similarly, at the subnet level we have the same thing.  A /48 is
2^16 bits of subnet, or 65536 subnets.  Now, I'll be the first to
admit I'd like to not have to use 1918 space for the 650 subnets I
have at home behind my 3Mbps cable modem, but giving me 100 times
that again prevents someone else from using the space who might
actually need it.

The problem with all of this is we're extremely bad predictors of
the future.  Back in the day, a /8 (16/8, to be specific) to DEC
seemed like they right thing to do, their big, they will grow.
Similarly, giving MCI a /24 ( to be specific) in 1993
seemed like a smart idea, they were just a small dial up e-mail
provider, after all.

So, while the IPv6 authors are busing thinking about my 65000 subnets
at home, and my 18 quintillion hosts per subnet they are forgetting
that the most interesting things that happen in the future are the
things we can't predict now.  Much as people laughed at the concept
that you would need a microprocessor in every doorknob in the 1960's,
we now regularly use them on a day to day basis in hotels and
businesses around the world.

We have people who are talking about allocating IPv6 addresses to
serve a 60 year need.  Well, that's all well and good, but it's
only 40 years after the doorknob quote and the reality is quite
different.  Ideas that seem far fetched today like colonizing mars,
or faster than light travel, or nanomachines that have IP stacks
may be so common place in 60 years time that no one gives them a
second thought.

What's most absurd about things like a /48 for cable modem users
is that it only promotes waste.  Having fixed addresses is great
/but only if you can take them with you/.  Well, if you can take
them with you that's an entry in the global table, which is not
what any of us want.  So presumably, you won't take them with you,
which means every time you move you'll be getting new IP's.  How
many people live in the same place for 60 years?  Can't we use these
external events to adjust the size of the blocks given out over

While I may look like a stodgy conservative when it comes to address
space management, I'l really not.  I'm pretty much a give it away
sort of guy....just on a sane scale.  Let's give every home a /104
(that is, the same amount of address space that's in a /8 today).
Further, let's go ahead and let them have 256 subnets, so it's a
/96 per house.  If I'm right that this is wanton waste, we just
recovered a 48 BITS of address space.  If I'm wrong, in 10 years
we can start giving out /80's to home users, 65,000 times the address
space, and still have recovered a full 32 bits of the address space.
That way when my grandchildren colonize alpha centauri and have
to number the six trillion whoiewhats that live there already they
will have plenty of space.

In other words, let's take a bath in the water, and enjoy that it
is plentiful, but let's not dump raw sewage into the lake "because
it doesn't matter".  History has a way of always making it matter.

       Leo Bicknell - bicknell at ufp.org - CCIE 3440
        PGP keys at http://www.ufp.org/~bicknell/
Read TMBG List - tmbg-list-request at tmbg.org, www.tmbg.org
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