Naive IPv6 (was AT&T UVERSE Native IPv6, a HOWTO)

Owen DeLong owen at delong.com
Wed Dec 4 20:50:42 UTC 2013


On Dec 4, 2013, at 12:43 , Brian Dickson <brian.peter.dickson at gmail.com> wrote:

> 
> 
> 
> On Wed, Dec 4, 2013 at 3:09 PM, Owen DeLong <owen at delong.com> wrote:
> 
> On Dec 4, 2013, at 10:21 , Brian Dickson <brian.peter.dickson at gmail.com> wrote:
> 
> Second of all, what would make much more sense in your scenario is
> to aggregate at one or two of those levels. I'd expect probably the POP
> and the Border device levels most likely, so what you're really looking
> at is 5000*100 = 500,000 /48s per border. To make this even, we'll
> round that up to 524,288 (2^19) and actually to make life easy, let's
> take that to a nibble boundary (2^20) 1,048,576, which gives us a
> /28 per Border Device.
> 
> 
> 
> Except that we have a hard limit of 1M total, which after a few 100K from the
> global routing tables (IPv4+IPv6), this 500,000 looks pretty dicey.
>  

Only if you feel the need to carry those global routes all the way down
to your border devices (which is unlikely in the kind of residential scenario
proposed).

> 
> > And root of the problem was brought into existence by the insistence that
> > every network (LAN) must be a /64.
> 
> Not really. The original plan was for everything to be 64 bits, so by adding
> another 64 bits and making every network a /64, we're actually better off
> than we would have been if we'd just gone to 64 bit addresses in toto.
> 
> Thanks for playing.
> 
> Owen
> 
> Understand, I am not saying anyone got it wrong, but rather, that there is a risk associated
> with continuing forever to use a /64 fixed LAN size. Yes, we are better than we
> were, but the point I'm making is, if push comes to shove, that the /64 is a small thing
> to sacrifice (at very small incremental cost, SEND + AUTOCONF modifications).
> 

I think it is already too entrenched to change, but I guess time will tell.

Since we are only talking about how we use the first 1/8th of the address space and we
didn't even exhaust that in your particularly overblown example, I am unconcerned.

> I can't believe I just called 2**64 small.

Well, it's smaller than 2^128. ;-)

Owen



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