Ditto Mark -

And I tend to disagree that if IPv6 did not have autoconfiguration feature, then IPv6 would have been devised with only 64 bits ?? It does not make sense coz then you are only increasing 32 bits more to the current size of the IP which IMO would not have been a significant increase in the IP size. IMO IPv6 was devised with 128 bits and was meant to address infinitely large number of hosts so that we never run out of addresses - and autoconfiguration etc were features added to IPv6 protocol later to make addressing easy.

I see autoconfiguration as a feature only and nothing more than that.

RFC 4291 does not pose any restriction or requirement on the IPv6 address assignment architecture that every subnet should or must be /64 or /48 etc and why it cannot be a /112 or something smaller.

From: Mark Tinka <mtinka@globaltransit.net>
To: Owen DeLong <owen@delong.com>
Cc: Skeeve Stevens <Skeeve@eintellego.net>; sig-policy@lists.apnic.net
Sent: Sunday, 18 September 2011 4:02 AM
Subject: Re: [sig-policy] Need to understand logic behind assigning /64 IPv6 addresses

On Sunday, September 18, 2011 01:43:13 AM Owen DeLong wrote:

> Multiple prefix sizes, address fragmentation, etc.
> Admittedly, it's a small complication, but, it is a
> complication.

> Further, it violates the principle of least surprise as
> your organization scales and brings in new engineers.

A good v6 address assignment policy for one's infrastructure
is neither difficult to create nor maintain.

No issues here since we started running v6 over 6 years ago.
We know how v6 can make address management within an ISP's
network brain-dead to maintain, but it's not reason enough
to use /64's where we can comfortably use /112's and still
not overly complicate our lives.

> So did I. I was being a little tongue in cheek/snarky
> with just presenting the math on the number of
> addresses,...

I know what you were getting at, with multiple v6 addresses
on a single interface, e.t.c.

> but the reality is that there may be some
> cases where having multiple addresses for one end of a
> point to point or the other (or both) may prove useful.
> These are admittedly rare.

Agree, but having run multiple networks with v6 over the
last several years, we're yet to find with a reason that has
required us to have multiple addresses on point-to-point
links either between infrastructure, or between AS domains.
Some things really are that simple :-).

Obviously, I can't speak for anyone else's network, just
ours.

Mark.

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