[128025] in North American Network Operators' Group
Re: Addressing plan exercise for our IPv6 course
daemon@ATHENA.MIT.EDU (Marco Hogewoning)
Fri Jul 23 04:07:47 2010
From: Marco Hogewoning <marcoh@marcoh.net>
In-Reply-To: <AANLkTilv90fjHaCpIgeYBlcokc_61TPoU1_PAZwudoKp@mail.gmail.com>
Date: Fri, 23 Jul 2010 10:06:43 +0200
To: Matthew Walster <matthew@walster.org>
Cc: nanog list <nanog@nanog.org>
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
On 23 jul 2010, at 01:33, Matthew Walster wrote:
> On 22 July 2010 14:11, Alex Band <alexb@ripe.net> wrote:
>> There are more options, but these two are the most convenient =
weighing all
>> the up and downsides. Does anyone disagree?
>=20
> I never saw the point of assigning a /48 to a DSL customer. Surely the
> better idea would be to assign your bog standard residential DSL
> customer a /64 and assign them a /56 or /48 if they request it, routed
> to an IP of their choosing.
/64 is too small, especially when sensornetworks take off you probably =
want multple ranges.
In fact the CPE we use at the moment already takes a /64 for internals =
like voip clients, dns resolver and management interfaces and assigns =
the second one to the LAN. Optionally you want people to create a =
seperate zone for wifi guests (it supports dual band radio). So in =
reallife you already need more then one.
Giving the way reverse DNS is designed I wouldn't recommend people to =
leave the 4 bit boundry on which it is organised unless you want to make =
your life miserable and complicated. So that would make it a /60 at =
minimum.
So why /48 and not /56 or /60 ? We'll first of all we, and I mean the =
collective group of people that tries to run the internet (which =
includes you reading this), screwed it up in marketing.
First of all we keep telling everybody there are so many addresses we =
will never run out of them. Now of course this is BS and we all know =
that someday we find 128 bits wasn't enough. By that time we probably =
realise that the current almost classfull system wasn't a smart choice =
and we introduce CIDR again to save our day.
Which brings me to the second point and that is introducing semi fixed =
borders like /64 for a subnet and the original wording 'if you think =
they ever need more then one subnet, assign a /48'. That amazingly got =
stuck in peoples head like classfull once did. I still have customers =
asking for a C-class and some of them are even born in the CIDR era. As =
far as the customer base understand what IPv6 is, all they ever hear is =
'I'll get a /48' even in those cases where you say something else. We =
told them NATs are going away and we told them we had so many addresses =
there wasn't a problem at all. /64 subnet, /48 when you need more did =
the rest.
So assume I assign the mass that is unaware a /64, do I reserve some =
bits for future growth? I'll bet you when IPv6 does hit the market =
somebody will find an application for it and requires a second subnet =
(sensors for instance). What do I do when somebody requests this, assign =
a secondary /64 or renumber ? So maybe I should reserve a /60, but is =
that different from assigning it directly ? Takes up space anyway.
So now I assign a /60, unfortunately the /48 is stuck in people's head =
so I get people complaining about this. This is amplified by the fact =
that early adopters, even the ones with tunnels, got a /48. Remember =
those folks who got a /8 back in the days, did you ever thought 'what if =
I would have been there' ? So I get into discussions with customers and =
that has a cost, I at least have to pay for the guy who answers the =
phone on our end. Next to that, there is that risk that I lose business =
because the shop across the road does offer /56 or even /48.
Which brings me into the economics, we are in a hurry. We need to deploy =
and we need to deploy yesterday. In fact if you are not running IPv6 by =
now, you are too late. So I have the choice of creating a really =
complicated deployment scheme in which I can assign variable subnet =
lenghts to customers without breaking aggregation and without annoying =
them with renumbering. One-size-fits-all makes life easy and saves an =
huge pile of money and not only money but it saves time, time I need, =
beacuse we are already a bit late.
In short, why a /48 'Because we can!'. We had about 15 years to design a =
proper scheme, we failed. Now we can discuss a redesign, but then we =
need to squeeze another 10 years out of IPv4.
MarcoH
