Subject: Re: [mobile-ip] RFC3012bis - Comments from ADs (Editorial)

From: Erik Nordmark <[email-masked]>
Date: Mon, 28 Oct 2002 17:34:25 +0100 (CET)

> > 6. Why does the document need to introduce two terms (previously used
> >    challenge and stale challenge) for the same thing?
> 
> The reason is because it makes certain sentence constructions
> more readable and convenient.  For instance:
>                 ...............        if the Foreign Agent
>    receives a Registration Request with a Challenge extension containing
>    a Challenge value previously used by that mobile node, ...
> 
> Using "stale" in that context makes the sentence structure
> inexact.  Of course, a lot of text could be rewritten
> to eliminate one term or the other, but that would be done
> only as a matter of conforming to personal taste, not to
> correct a problem in the specification.

I don't understand why using a well-defined term would make the
sentence structure inexact. Perhaps the issue is instead that
both "stale" and "previously used" carry some english language semantics
which in some cases can be seen as conflicting with the defined meaning
in the document. If that is the case I'd propose using a new defined
term such as "expired" in the document and state in the definition that
challenges can be expired either because they have already been used
or because they have become too old.

> > 10.  chosen as CHAP_SPI (see section 9), then the mobile node
> >        specifies
> >      Should be section 10.
> 
> Section 10 is for error values, not constants... (?)

Hmm - I must have misread the document. It is indeed defined in section 9
but my scribblings from reading the document captured my confusion that
it was defined in section 10.

  Erik

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From: "Jayshree Bharatia" <[email-masked]>
Date: Mon, 28 Oct 2002 12:41:51 -0600

Please see my response below marked with [JB].

Thanks,
Jayshree

[JB] For setting up "Stale" challenge, it seems, the Foreign Agent is
comparing the challenge received in the Registration Request and identifying
that it as a "previously used challenge" but sets the error code as
Stale_Challenge. There is no clear difference between these two terms other
than whether the foreign Agent has any record of previously used challenges.

Since we don't mandate how many prior-used challenges are kept at the
foreign agent, I would suggest combining these two terms. Using "Expired"
would work also. But generally, this term is used with some kind of
monitoring mechanisms. I would prefer to have term "duplicate" and the
terminology rewritten in section 1.1 as below:

Duplicate challenge: Any challenge that has been used by the mobile node in
a Registration Request message and processed by the Foreign Agent earlier by
relaying or generating a corresponding Registration Reply message. 

Any comments?

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From: "Ahmad Muhanna" <[email-masked]>
Date: Mon, 28 Oct 2002 15:31:13 -0600

Hello Jayshree,
Please see my comments inline.

Regards; 
Ahmad Muhanna 

Since we don't mandate how many prior-used challenges are kept at the
foreign agent, I would suggest combining these two terms. 

<<Ahmad-START>>
This is the key here.
We do not want to limit the FA implementation of how many previously used
Challenge it SHOULD track.
Probably eliminating the definition for stale challenge and modifying the
previously used challenge to read as follows will satisfy every one:

      previously used challenge
               Any challenge that has been used by the mobile node in
               a Registration Request message and processed by the
               Foreign Agent by relaying or generating a corresponding
               Registration Reply message. The Foreign Agent may not be 
               able to keep records for all previously used challenges, 
               but see section 3.2 for minimal requirements.

What do you think?

<<Ahmad-END>>

Using "Expired" would work also. But generally, this term is used with some
kind of monitoring mechanisms. I would prefer to have term "duplicate" and
the terminology rewritten in section 1.1 as below:
Duplicate challenge: Any challenge that has been used by the mobile node in
a Registration Request message and processed by the Foreign Agent earlier by
relaying or generating a corresponding Registration Reply message. 
Any comments?