Re: [nat66] Comments on draft-mrw-nat66-12

"S.P.Zeidler" <spz@serpens.de> Wed, 16 March 2011 07:08 UTC

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Date: Wed, 16 Mar 2011 08:09:39 +0100
From: "S.P.Zeidler" <spz@serpens.de>
To: Brian E Carpenter <brian.e.carpenter@gmail.com>
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Cc: NAT66 HappyFunBall <nat66@ietf.org>
Subject: Re: [nat66] Comments on draft-mrw-nat66-12
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Thus wrote Brian E Carpenter (brian.e.carpenter@gmail.com):

> On 2011-03-16 11:51, Fred Baker wrote:
> ...
> > people don't spend a lot of cycles thinking about NAPT44 route flap effects. 
> 
> The interesting thing is that people don't spend cycles thinking about
> any of the NAT-induced glitches which cause end users to lose sessions;
> some of these will apply to NPTv6 of course. I wonder if it's possible
> to quantify this (rough % of sessions lost by NAPT44 glitches, and
> how many of these would *not* occur with NPTv6)?

You get NAPT44 glitches under two circumstances, in my experience:
- your NAT gateway is buggy or overwhelmed and loses NAT state ->
  single sessions fail randomly
- your NAT gateway reboots, all sessions that were going previously are
  toast

Both are due to the statefulness of NAPT44. Since NPTv6 is stateless,
I do not expect either to apply. (Modulo "it's buggy as an ant farm", but
that's not a protocol failure, especially not of the protocol algorithm
is fairly simple).

If an outside link fails, I would say it was unfair to blame the NPTv6 for
the sessions across it failing; it's not the cause, the sessions would
have died without translation just the same.

regards,
	spz
-- 
spz@serpens.de (S.P.Zeidler)