Subject: RE: [Mip4] RFC3012bis: Proposal for Issue2-Change5

From: "Jayshree Bharatia" <[email-masked]>
Date: Thu, 4 Sep 2003 16:03:46 -0500

Hi Pete,

My response below...

Thanks,
Jayshree

> -----Original Message-----
> From: Pete McCann [mailto:[email-masked]] 
> Sent: Thursday, September 04, 2003 2:35 PM
> To: Bharatia, Jayshree [RICH1:2H13:EXCH]
> Cc: [email-masked]'
> Subject: RE: [Mip4] RFC3012bis: Proposal for Issue2-Change5
> 
> 
> 
> Hi, Jayshree,
> 
> Jayshree Bharatia writes:
>  > > I would be fine if we deleted the one sentence "The Foreign 
>  > > Agent could then assume..." from the above (it has no 
>  > > normative value anyway).
>  > > 
>  > [JB] I rather have just "MUST" instead of "SHOULD" in the 
> current text  > without any further conditional text if it 
> solves all your concerns.
> 
> Are you saying to include a challenge in every registration 
> reply or agent advertisement?  Well, that would be ok with 
> me, but we got pushback from Charlie on this.  I don't want 
> to put words in his mouth, so go back and re-read his posts 
> from the archive.  I think he felt that an always MUST was 
> too strong, as there were conditions where it could be left 
> out.  We were trying to pin down those conditions, which I 
> think my suggested text does.

[JB] I am very well aware of Charlie's email on this subject (quoted below):
"The foreign agent "should" be allowed to rely on letting the mobile nodes
use the advertised values when it is likely that will be successful. Good
systems could be built that way." 
Since you are still suggesting having conditional text with the use of
"MUST", I assume that in your opinion having "SHOULD" is not appropriate and
hence you disagree with Charlie's reply. My point here is, if I have to
choose from using  "MUST" with your conditional text or  "MUST" without the
conditional text, I rather use just "MUST" without any condition. Anyway, I
would let Charlie reply on this. I am fine with either using "SHOULD" as
suggested by Charlie or using "MUST" without any condition.

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---

From: Henrik Levkowetz <[email-masked]>
Date: Fri, 5 Sep 2003 01:13:15 +0200

Thursday  4 September 2003, Jayshree wrote:
...
> suggested by Charlie or using "MUST" without any condition.

??? Jayshree, the only one who seems to have advocated MUST instead of
SHOULD in the original text recently seems to have been you, above. I
think both Pete and myself have assumed that we would let the original
paragraph stand as-is, with SHOULD, but explain more closely in
following text under which conditions the SHOULD does and doesn't apply.
Let me re-iterate my latest proposal, which I still think is good :-)  :

"3.3. Foreign Agent Processing for Registration Replies

   The Foreign Agent SHOULD include a new Mobile-Foreign Challenge
   Extension in any Registration Reply, successful or not.  If the
   foreign agent includes this extension in a successful Registration
   Reply, the extension SHOULD precede a Mobile-Foreign authentication
   extension.  Suppose the Registration Reply includes a Challenge
   extension from the Home Agent, and the foreign agent wishes to
   include another Challenge extension with the Registration Reply for
   use by the mobile node.  In that case, the foreign agent MUST delete
   the Challenge extension from the Home Agent from the Registration
   Reply, along with any Foreign-Home authentication extension, before
   appending the new Challenge extension to the Registration Reply.
  
   One example of a situation where the Foreign Agent MAY omit the
   inclusion of a Mobile-Foreign Challenge Extension in the Registration
   Reply would be when a new challenge has been multicast recently. The
   Foreign Agent could then assume that the mobile node with high
   likelihood has received and can use the multicast challenge. 
  
   If a foreign agent has conditions in which it omits the inclusion of a
   Mobile-Foreign Challenge Extension in the Registration Reply, it still
   MUST respond with an agent advertisement containing a previously unused
   challenge in response to a subsequent agent solicitation from the same
   mobile node.  Otherwise (when the said conditions are not met) the
   foreign agent MUST include a previously unused challenge in any
   Registration Reply, successful or not.
  
   A mobile node MUST be prepared to use a challenge from a unicast or
   multicast Agent Advertisement in lieu of one returned in a Registration
   Reply, and MUST solicit for one if it has not already received one in a
   Registration Reply.

..."

	Henrik

---

From: Pete McCann <[email-masked]>
Date: Thu, 4 Sep 2003 18:11:25 -0500

Hi, Jayshree,

 > suggested by Charlie or using "MUST" without any condition.

The MUST with an "unless" condition is a little weaker than a strict
MUST, while being stronger than a SHOULD, so I was hoping it would
make everyone happy.  Can you tell me why you don't like the "unless"
condition?

-Pete