Re: 6MAN WG Last Call:draft-ietf-6man-ipv6-subnet-model-00.txt

Thomas Narten <narten@us.ibm.com> Thu, 10 July 2008 01:29 UTC

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To: JINMEI Tatuya / =?ISO-2022-JP?B?GyRCP0BMQEMjOkgbKEI=?= <Jinmei_Tatuya@isc.org>
Subject: Re: 6MAN WG Last Call:draft-ietf-6man-ipv6-subnet-model-00.txt
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References: <B00EDD615E3C5344B0FFCBA910CF7E1D04E41EB4@xmb-rtp-20e.amer.cisco.com> <BB56240F3A190F469C52A57138047A03A9E94F@xmb-rtp-211.amer.cisco.com> <m2lk0b6d24.wl%Jinmei_Tatuya@isc.org>
Comments: In-reply-to JINMEI Tatuya / =?ISO-2022-JP?B?GyRCP0BMQEMjOkgbKEI=?= <Jinmei_Tatuya@isc.org> message dated "Tue, 08 Jul 2008 18:50:27 -0700."
Date: Wed, 09 Jul 2008 21:29:40 -0400
From: Thomas Narten <narten@us.ibm.com>
Cc: ipv6@ietf.org, Bob Hinden <bob.hinden@nokia.com>, Brian Haberman <brian@innovationslab.net>
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Note: replying to a number of separate messages here...

JINMEI Tatuya / =?ISO-2022-JP?B?GyRCP0BMQEMjOkgbKEI=?=
 <Jinmei_Tatuya@isc.org>; writes:

> At Thu, 3 Jul 2008 17:07:34 -0400,
> "Wes Beebee (wbeebee)" <wbeebee@cisco.com>; wrote:

> > <wb>
> > What if there are cache-inconsistency problems, prefix renumbering, or
> > stale information?  I think it's better just to get rid of caching
> > on-link information in stable storage and get such information fresh
> > from RA's.  That way, administrators can better rationalize the behavior
> > of their network from the configured RA's.
> > </wb>

> The same argument applies to caching the address, so it cannot be a
> reason why we specifically prohibit the (on-link) prefix part of this
> behavior.

Exactly.

> Actually, I see it can rather be harmful if we only prohibit the
> on-link prefix part of this behavior.

Again, I agree.

Note also, that DNA approaches essentially "cache" information about
the configuration of an interface across interfaces going up and down
-- which is very similar to the type of caching you are proposing to
disallow.

There is nothing wrong with caching information (as long as it has not
expired) so long as one replaces it if updated information comes along
later.

So I continue to be unpersuaded by any of the discussion so far that
we should saying "don't do that". 

Thomas

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