Tatuya,
Since you don't want any new rules added by our draft, we changed bullet
3 related to caching on-link determination. The new bullet text does not
add any normative requirements but clearly says why it is a bad idea to
cache on-link determination. Also, our draft is about on-link
determination - we are not adding anything related to IPv6 address
caching - we have said repeatedly, save it for another day.
The old text of bullet 3 was:
On-link determination SHOULD NOT persist across IPv6 interface
initializations. Note that section 5.7 of [RFC4862] describes
the use of stable storage for addresses acquired with stateless
address autoconfiguration with a note that the Preferred and
Valid Lifetimes must be retained if this approach is used.
However no RFC suggests or recommends retaining the on-link
prefixes.
New text is as follows:
If on-link determination persists across IPv6
interface initializations,
then lack of IPv6 connectivity can result. For
example, a host receives
an RA from a router with on-link prefix A. The host
reboots. During the
reboot, the router sends out prefix A with on-link bit
set and a zero
lifetime to indicate a renumbering. The host misses
the renumbering.
The host comes online. Then, the router sends an RA
with no PIO.
The host uses cached on-link prefix A and issues NS's
instead of sending
traffic to a default router. The "Observed Incorrect
Implementation Behavior"
section below describes how this can result in lack of
IPv6 connectivity.
Hemant
-----Original Message-----
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]
Sent: Thursday, July 10, 2008 1:15 AM
To: Hemant Singh (shemant)
Cc: Wes Beebee (wbeebee); Thomas Narten; Brian Haberman; Bob Hinden;
ipv6@ietf.org
Subject: Re: 6MAN WG Last Call:draft-ietf-6man-ipv6-subnet-model-00.txt
At Wed, 9 Jul 2008 20:54:04 -0400,
"Hemant Singh (shemant)" <[EMAIL PROTECTED]> wrote:
> Thanks for the reply. Let's see if we can meet common ground with you.
>
> Our justification for prohibiting on-link caching is only in emails to
> 6man as follows:
>
> "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."
And I replied to this justification, saying this itself cannot justify
killing on-link caching while (perhaps implicitly) allowing address
caching.
> Also, when Suresh Krishnan pointed out that he supports bullet 3, he
> made us explicitly mention in the bullet that it's a new rule. We have
> been clear in the draft where there is a new rule and where it's
> clarification. Besides this new rule, the rest of the draft is
> clarification.
Suresh has his right to express his opinion, of course, and so do I.
I would not like this document to set new rules (note, again, that I'm
not objecting to discussing new changes to RFC4861/4862. I'm simply
objecting to doing that in this document).
---
JINMEI, Tatuya
Internet Systems Consortium, Inc.
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