[121733] in North American Network Operators' Group
Re: Using /126 for IPv6 router links
daemon@ATHENA.MIT.EDU (Mark Smith)
Mon Jan 25 23:07:09 2010
Date: Tue, 26 Jan 2010 14:36:57 +1030
From: Mark Smith <nanog@85d5b20a518b8f6864949bd940457dc124746ddc.nosense.org>
To: "TJ" <trejrco@gmail.com>
In-Reply-To: <000001ca9dfb$3599e270$a0cda750$@com>
Cc: nanog@nanog.org
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
On Mon, 25 Jan 2010 15:15:55 -0500
"TJ" <trejrco@gmail.com> wrote:
> > -----Original Message-----
> > From: Tim Durack [mailto:tdurack@gmail.com]
> > Sent: Monday, January 25, 2010 14:03
> > To: TJ
> > Cc: nanog@nanog.org
> > Subject: Re: Using /126 for IPv6 router links
>
> <<snip>>
>
> >
> > 2^128 is a "very big number." However, from a network engineering
> > perspective, IPv6 is really only 64bits of network address space. 2^64
> > is still a "very big number."
> >
> > An end-user assignment /48 is really only 2^16 networks. That's not
> > very big once you start planning a human-friendly repeatable number
> > plan.
> >
> > An ISP allocation is /32, which is only 2^16 /48s. Again, not that big.
> >
> > Once you start planning a practical address plan, IPv6 isn't as big as
> > everybody keeps saying...
>
>
> I didn't realize "human friendly" was even a nominal design consideration,
> especially as different humans have different tolerances for defining
> "friendly" :)
>
This from people who can probably do decimal to binary conversion
and back again for IPv4 subnetting in their head and are proud of
it. Surely IPv6 hex to binary and back again can be the new party
trick? :-)
> I (continue to) maintain that:
> *) 2^16 is still a pretty good size number, even allowing for aggregation /
> summarization.
> *) If you are large enough that this isn't true - you should (have)
> request(ed) more, naturally - each bit doubles your space ...
>
>
>
> /TJ
>
>
>
