Subject: [manet] Mirja Kühlewind's No Objection on draft-ietf-manet-rfc5444-usage-06: (with COMMENT)

From: Mirja Kühlewind <[email-masked]>
Date: Sat, 01 Jul 2017 05:29:58 -0700

Mirja Kühlewind has entered the following ballot position for
draft-ietf-manet-rfc5444-usage-06: No Objection

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COMMENT:
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One question:
I’m wondering why the following is not a MUST. Can you maybe provide more
information in the draft when modification might be okay? „It is strongly
RECOMMENDED that messages are not modified in the
      latter case, other than updates to their hop count and hop limit
      fields“

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From: Christopher Dearlove <[email-masked]>
Date: Sat, 1 Jul 2017 17:00:20 +0100

Mirja

Thank you for that.

The short version is that the position strongly recommended was the WG consensus. The authors of this draft, and of NHDP and OLSRv2, could definitely have lived with a MUST for those protocols. However reactive protocols (such as the then still active AODVv2 draft) have a problem with unmodifiable messages if a route reply is to collect any information on its return path, something that is required if using link metrics. (At least not without other serious problems.)

So, in short, there's a use case that would violate a MUST. But it should be avoided if possible, hence the agreed wording.

--  
Christopher Dearlove
[email-masked]

> On 1 Jul 2017, at 13:29, Mirja Kühlewind <[email-masked]> wrote:
> 
> _______________________________________________
> manet mailing list
> [email-masked]
> https://www.ietf.org/mailman/listinfo/manet

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From: Spencer Dawkins at IETF <[email-masked]>
Date: Tue, 4 Jul 2017 15:43:34 -0500

Hi, Christopher,

On Sat, Jul 1, 2017 at 11:00 AM, Christopher Dearlove <
[email-masked]> wrote:

> Mirja
>
> Thank you for that.
>
> The short version is that the position strongly recommended was the WG
> consensus. The authors of this draft, and of NHDP and OLSRv2, could
> definitely have lived with a MUST for those protocols. However reactive
> protocols (such as the then still active AODVv2 draft) have a problem with
> unmodifiable messages if a route reply is to collect any information on its
> return path, something that is required if using link metrics. (At least
> not without other serious problems.)
>
> So, in short, there's a use case that would violate a MUST. But it should
> be avoided if possible, hence the agreed wording.

I won't include this in my No Objection ballot, because you and Mirja are
already chatting about it, but if you have a specific reason in mind for
not using MUST ("being used with a reactive protocol"), saying "SHOULD
unless" would leave less room for future mischief.

And your response helped my understanding a lot, so I hope future readers
would also benefit from that explanation.

Do the right thing, of course.

Spencer