Subject: IPv6 destination options questions...

From: Dan McDonald <[email-masked]>
Date: Sun, 18 Feb 2001 16:04:35 -0800 (PST)

This sort of minutiae begs for reality checking.

In the IPv6 spec (RFC 2460), you can see "destination options" occur in TWO
places in an unprotected packet.  The first place is the obvious place of
just-before-the-transport-header.  The second place is the more subtle
just-before-the-routing-header, which has the semantic of making every node
specified in the routing header process the destination options.

My questions are:

	1.) In the routing header case, can those specified nodes change
	    destination options inside that header between routing header hops?

	2.) If #1's answer is "yes", must those options have the "mutable"
	    bit set in them?

	3.) In the just-before-transport case, is there any reason for any
	    "mutable" options to be in that dest-opts bag?

(The correct answer for the second part (IMHO) is "yes".  The correct answer
for the third part (again, IMHO) is "no".)

Clear, precise answers to these questions makes AH for IPv6 implementable.
These answers should also appear in the sucessor spec to RFC 2460 (and
probably 2402 as well, but that's for another list).

Thanks,
Dan
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From: Robert Elz <[email-masked]>
Date: Mon, 19 Feb 2001 08:23:53 +0700

Date:        Sun, 18 Feb 2001 16:04:35 -0800 (PST)
    From:        Dan McDonald <[email-masked]>
    Message-ID:  <[email-masked]>

  | (The correct answer for the second part (IMHO) is "yes".  The correct answer
  | for the third part (again, IMHO) is "no".)

I agree, and that also assumes that the answer to the first question
is yes as well.   This was all discussed on the list a few months ago
(in amongst the big debate on what the API ought be like for setting
the multiple possible DO headers)

kre

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From: Francis Dupont <[email-masked]>
Date: Mon, 19 Feb 2001 11:36:53 +0100

In your previous mail you wrote:

=> do you know the discussion about this at the last IETF meeting?

=> no, an application (like mobile IPv6) can specify another place
(like just-after-the-routing-header (if any) and just-before-
the-fragmentation-header (if any)).

   My questions are:

=> yes

=> yes

=> no

=> I agree. I suggested to fix the last point in (future) definitions
of mutable options because to ask for support of mutable options after
an AH is *silly*.

=> I tried to fix the whole issue with destination options (read
draft-dupont-destoptupd-00.txt) but the decision at the last IETF
was not to add new name/type in order to manage the different
destination option header positions but was to change the advanced API
in order to express this complexity.

Thanks

[email-masked]

PS: ask Eric about advanced API proposed changes.