[ppml] Re: 2005-1:Multi-national Business Enablement

On Thu, Apr 28, 2005 at 06:56:04AM -0500, Stephen Sprunk wrote:
> Thus spake "Daniel Roesen" <dr at cluenet.de>
> > On Sun, Apr 24, 2005 at 09:13:48AM -0500, Stephen Sprunk wrote:
> > > > Nope. They should get a /48 unless they can convincingly show that
> > > > they'll never need more than a single subnet.
> > >
> > > It is ridiculous to think that ISPs are going to completely discard
> their
> > > current IPv4 topology to deploy IPv6.
> >
> > Why must they discard any topology?
> 
> IPv6 mandates a particular topology and disallows others which happen
> to be in widespread use by IPv4 ISPs.

I have problems imagining both. Can you give me an example?

> > > Most "residential" ISPs I'm aware of use a single subnet for N
> > > customers,
> >
> > Hm? I guess you are referring to cable modem stuff?
> 
> It's common for cable, DSL, wireless, and other technologies.  For
> instance, my landlord provides a straight ethernet connection into
> my residence (which is connected to a T1); with DHCP, I consume only
> one IP per PC.  For them to offer me an IPv6 /48 or even /64, they'd
> need to change their IPv4 addressing to a /30 or shorter for each
> customer, wasting four addresses for a customer with one PC.

But that's considered perfectly fine use of those addresses, not
"waste". Sure, the result are unused addresses, but the way of usage
if sound.

I do generally consider a shared L3 subnet a mistake by itself,
especially for security reasons (I know there are methods to battle
those).

> > Over here (DE), almost all residential users use dial-up, be it real
> > (analog, ISDN) or virtual (DSL, via PPPoE). So they are connected via
> > virtual interfaces, and get their IP address usually via dynamic pools
> > or static via RADIUS. No problem adapting this to assign /48s
> > (especially via RADIUS).
> 
> If that's the topology, then that makes sense.  However, it's not the
> dominant topology in the US today.

And global IPv6 policies should adapt to US legacy? Or what are you
asking for?

[my presumption is that we want to reach global policies, not regional
ones for that]

> > The mantra is "/48, no questions asked, and by default".
> 
> When you consider how that affects the IPv4 topology, that doesn't make
> sense in many cases.  If we're going to share subnets across customers in
> IPv4, we need to do the same for IPv6.

Not necessarily. You might take it as a starting point to migrate
your legacy setup to a possibly better one. :-)

But well, I don't care if US ISPs are giving only /64s to their
customers. I do enjoy living in EU where I hope that /48s will be the
default (a man needs to dream once in a while). *g*


Best regards,
Daniel

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