[121717] in North American Network Operators' Group
RE: Using /126 for IPv6 router links
daemon@ATHENA.MIT.EDU (TJ)
Mon Jan 25 15:16:11 2010
From: "TJ" <trejrco@gmail.com>
To: <nanog@nanog.org>
In-Reply-To: <9e246b4d1001251102u2b6ca6b1le4b7f259ea2d505b@mail.gmail.com>
Date: Mon, 25 Jan 2010 15:15:55 -0500
Errors-To: nanog-bounces+nanog.discuss=bloom-picayune.mit.edu@nanog.org
> -----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" :)
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
