AT&T UVERSE Native IPv6, a HOWTO

Mark Andrews marka at isc.org
Thu Nov 28 22:56:38 UTC 2013


In message <CAPKkNb6Nhr-bcvkTwTjf+rFovhYjv0+xyCPM6D4CndvZn3FqeA at mail.gmail.com>
, "Constantine A. Murenin" writes:
> On 28 November 2013 13:07, Leo Vegoda <leo.vegoda at icann.org> wrote:
> > Andrew D Kirch wrote:
> >
> > Was I the only one who thought that everything about this was great
> > apart from this comment:
> >
> >> In reality additional poking leads me to believe AT&T gives you a
> > rather
> >> generous /60
> >
> > Is a /60 what is considered generous these days? I thought a /48 was
> > considered normal and a /56 was considered a bit tight. What prefix
> > lengths are residential access providers handing out by default these
> > days?
> 
> Remember, this is just 6rd.  With 6rd, a /60 does sound quite generous indeed
> .

You can hand out /48 as easily with 6rd as you can natively.

It's only when the ISP is lazy and encodes the entire IPv4 address
space into 6rd thereby wasting most of the IPv6 address space being
used for 6rd that a /60 appears to be generous.

You can do a 6rd domain per IPv4 allocation.  This is a one time
operation that doesn't need to be updated as you move IPv4 address
space around.

> And it's a /60 for each IPv4 you have, e.g. if you have a static IP
> allocation with AT&T U-verse, say, a /27, then you're effectively
> getting a /55 (plus also an additional /60 for the DHCP address in a
> shared subnet to which your /27 is routed to).
> 
> That said, I wholeheartedly agree with your comment otherwise.
> 
> C.
> 
-- 
Mark Andrews, ISC
1 Seymour St., Dundas Valley, NSW 2117, Australia
PHONE: +61 2 9871 4742                 INTERNET: marka at isc.org




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