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

heasley <heas@shrubbery.net> Fri, 13 January 2017 20:03 UTC

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Date: Fri, 13 Jan 2017 20:03:34 +0000
From: heasley <heas@shrubbery.net>
To: Lorenzo Colitti <lorenzo@google.com>
Subject: Re: Review of draft-ietf-6man-rfc4291bis-06
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Fri, Jan 13, 2017 at 04:40:19PM +0900, Lorenzo Colitti:
> 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.

do such limited devices really need complex ribs/fibs?  address, router,
neighbors.  all of which are needed regardless of the prefix length.

> Prefixes
> don't cost money,

but, they do: https://www.arin.net/fees/fee_schedule.html

> and if we know that we won't run out of them

do we know this?  and 640k RAM is plenty.  i'm not convinced.

> the problem?

rfc6164 s5.1, s5.2.  s5.2 applies to your ram-limited devices.  end users
that want to subnet can't w/o additional /64s.