Re: Review of draft-ietf-6man-rfc4291bis-06

John C Klensin <john-ietf@jck.com> Sat, 14 January 2017 03:07 UTC

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Date: Fri, 13 Jan 2017 22:06:54 -0500
From: John C Klensin <john-ietf@jck.com>
To: Lorenzo Colitti <lorenzo@google.com>, Randy Bush <randy@psg.com>
Subject: Re: Review of draft-ietf-6man-rfc4291bis-06
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--On Friday, January 13, 2017 16:40 +0900 Lorenzo Colitti
<lorenzo@google.com> wrote:

> But it's true that supporting /65-/126 increases the cost of
> the device. The extra bits have to go somewhere. I think I've
> seen hardware that just converted all prefixes to 128 bit if
> there was at least one /65 - /126 prefix in the FIB. That
> costs money for RAM. Obviously that's silly if those prefixes
> are frequent, and you can save that money using better
> software engineering - but software engineering costs money
> too. Prefixes don't cost money, and if we know that we won't
> run out of them, what's the problem?

Because you can pick the scenario -- lots of "things", an
interplanetary network, both, or something else-- but we have
been here before.   Every time someone has said "there is so
much address space that we will never run out no matter how
inefficiently we use them", they have eventually been proven
wrong.  That history is obviously not just with the
ARPANET/Internet or even computer networks: "if we know we won't
ever run out of them" has a nasty tendency to prove that we
didn't know and didn't get it right.

     john