[134762] in North American Network Operators' Group
RE: IPv6 - real vs theoretical problems
daemon@ATHENA.MIT.EDU (Tony Hain)
Mon Jan 10 17:02:49 2011
From: "Tony Hain" <alh-ietf@tndh.net>
To: "'NANOG list'" <nanog@nanog.org>
In-Reply-To: <4D2B6A81.7000002@nasa.gov>
Date: Mon, 10 Jan 2011 14:02:14 -0800
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
*requested anonymous* wrote:
> (I don't post on public mailing lists, so, please consider this
> private.
> That is, I don't care if the question/reply are public, just, not the
> source.)
>=20
> On 1/10/11 11:46 AM, Tony Hain wrote:
> > ... yes I know you understand operational issues.
> >
> > While managed networks can 'reverse the damage', there is no way to
> fix that
> > for consumer unmanaged networks. Whatever gets deployed now, that is
> what
> > the routers will be built to deal with, and it will be virtually
> impossible
> > to change it due to the 'installed base' and lack of knowledgeable
> > management.
> >
> > It is hard enough getting the product teams to accept that it is
> possible to
> > build a self-configuring home network without having that be =
crippled
> by
> > braindead conservation. The worst possible value I can see for
> delegation to
> > the home is /56, yet that is the most popular value because people
> have
> ^^^^^^^^^^^^^^^^^
> Why would you say /56 is the worst possible value? Just curious --
I am actually trying to develop a simple set of 'auto conf' rules for =
all the CPE vendors to build against, and for a Joe-sixpack plug-n-play =
network configuration a /56 means there is only one topology option =
beyond single subnet.=20
> my provider doesn't offer IPv6 yet, but, I think they will soon.
> I was going to ask for a /56 for my home net. If I ever get around
> to using them to set up a domain for my wife's business, I will ask
> for a /48, but, for a house without a private domain, /56 seems
> perfect.
You are thinking of a managed network. Connect a random graph of boxes, =
then figure out a subnet scheme that all cpe vendors can implement that =
will correctly deal with prefix delegation and hierarchical routing.=20
> I don't expect to run out in my lifetime, or even my children's
> or grandchildren's lifetimes if somehow the house stays in the family
> ;-)
> How many subnets will they really need, no matter if every lightbulb
> is on the net?
Wrong question. In a managed network that would be the right question, =
but in an unmanaged one the right question is how many sub-delegations =
and how many branches per sub-delegate are going to be automatically =
figured out.=20
>=20
> My frame of reference is that while we need to make the addresses big
> enough, we also need to preserve the hierarchy. There is no shortage
> of addresses, nor will there be, ever, but there could be a shortage
> of levels in the hierarchy. I assume you would like a home to have a
> /48? But, from my provider's /32, that is only 4 levels at the
> assumed nibble boundary. I think my provider could use another
> two levels.
If your provide has more than 10,000 customers they should never have =
gotten a /32. The braindead notion that everyone needed to rush out and =
get a /32 has not helped get IPv6 deployed. The /32 value was the =
default one for a startup provider. Every provider with a customer base =
should have done a plan for a /48 per customer, then gotten the right =
size block to start with. Any provider with a /32 and more than 10k =
customers needs to do that now and swap for 'a real block', instead of =
trying to squeeze their customers into a tiny block due to their =
insufficient initial request.=20
>=20
> I also think ~256 subnets has stood the test of time -- seldom in
> the last 25 years has a geographically contiguous enterprise network
> (such as a university or company) required more than 256 subnets --
> except for cisco, microsoft, et al., but not, e.g. most colleges,
> universities, research centers, etc. More addresses, sure, but,
> not usually more than 256 subnets. So, even in a world where
> every possible device has its own set of addresses -- how many
> subnets will I really need?
Again, wrong question. Most of the possible subnets in a Joe-sixpack =
configuration will be 'wasted'. So what? That space will be wasted =
sitting on the shelf at IANA in 500 years when someone comes up with a =
better idea. IPv6 is not the last protocol known to mankind (unless the =
2012 predictions are true), so most of its potential space will be =
wasted. Get over that point and accept that innovation requires thinking =
differently than the limited myopia of the past.
>=20
> Also from my frame of reference -- we need to work on making =
addressing
> and re-addressing easier and more automatic for consumers anyway, so,
> if /56 is not enough, we can easily and painlessly switch to a /52
> with no problems. =20
Easy in a managed network where it is possible to update code and expect =
that things will happen in a timeframe that makes development worth the =
effort. Impossible in consumer land where it is well documented that =
things are never updated, and all vendors need to play by the same =
simple rules because there is no hope that the consumer will know how to =
tweak them.
> And, if I decide to grow an enterprise from home,
> I feel that I should be able to re-address as needed over the course
> of time anyway, so, I would rather make re-addressing easier than
> put all my eggs in the large-enough-/48 basket. What if I grow so
> large that I buy someone else's company, or otherwise merge? We have
> to solve the re-addressing problem anyway, in which case, /48, /52, =
/56
> assignments should not be a big deal.
>=20
> What am I missing?
You are thinking like every other network engineer on Nanog, not like a =
consumer that doesn=E2=80=99t understand why some configurations are not =
possible. The only way to avoid support calls is to make it trivial for =
the devices to deal with just about anything that a consumer might do, =
and it has to be scalable enough over time to deal with the fact that a =
device from today will still be in use 10-15 years from now. Evolution =
of the rules is possible over very long timeframes, but more complex and =
costly. Starting with a short-sighted, managed network viewpoint is a =
guarantee that it will be impossible to innovate in the unmanaged home =
network space.
Tony
