Subject: [Roll] Barry Leiba's Discuss on draft-ietf-roll-mpl-parameter-configuration-06: (with DISCUSS and COMMENT)

From: "Barry Leiba" <[email-masked]>
Date: Tue, 07 Jul 2015 11:18:03 -0700

Barry Leiba has entered the following ballot position for
draft-ietf-roll-mpl-parameter-configuration-06: Discuss

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DISCUSS:
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This should be a very easy discussion to resolve:

-- Section 2.3 --

   A node SHOULD leave an MPL domain if it receives an updated MPL
   Parameter Configuration Option without a configuration for the MPL
   domain, unless it has overriding manual configuration on the MPL
   domain.  In other words, if a node is configured to work as a MPL
   Forwarder for a MPL domain regardless of DHCPv6 Options, the node MAY
   stay on the MPL domain even if it receives an MPL Parameter
   Configuration Option without configuration for the MPL domain.

I'm confused by this, because it appears to contradict itself.

Some questions might help he understand:

If I receive an updated MPL PCO that lacks a config for the MPL domain,
then there are two possible situations:

Case 1: I do *not* have an overriding manual config for the domain.  In
this case, the text says that I SHOULD leave the domain.  Is that
correct?  Is it OK in this case for me to decide to stay on the domain
anyway, even if I have no manual configuration for it?

Case 2: I *do* have an overriding manual config for the domain.  In this
case, the text seems to say that it's entirely my choice ("MAY") whether
or not I stay on the domain or leave it.  Is that correct?

Please discuss this with me, so I can suggest how to make the text
clearer, depending upon the answers to those questions.

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COMMENT:
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-- Section 2.1 --

   option_len:  Length of the option.  It SHOULD be 16 (without MPL
      domain address) or 32 (with MPL domain address).

"SHOULD", really?  What else *can* it be, and still be valid?  Is there
any legitimate reason I might make it something else?  Or should this
just say this?:

NEW?
   option_len:  Length of the option, which is 16 if no MPL domain
      address is present, or 32 if there is an MPL domain address.
END

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From: "Alvaro Retana (aretana)" <[email-masked]>
Date: Wed, 8 Jul 2015 22:04:02 +0000

On 7/7/15, 3:18 PM, "Barry Leiba" <[email-masked]> wrote:

Barry:

Hi!

Yes..I can see how this is confusing, and I think the fix is easy: remove
the second sentence.  This second sentence doesn¹t add new information and
it makes the text confusing by adding the ³MAY².

I¹ll let Yusuke confirm that this is ok (and address your other comment).

Thanks!

Alvaro.

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From: Yusuke DOI <[email-masked]>
Date: Thu, 09 Jul 2015 08:38:40 +0900

Hi Alvaro,

> I¹ll let Yusuke confirm that this is ok (and address your other comment).

I agree with the fix. Thank you for suggestion.

Yusuke

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From: Barry Leiba <[email-masked]>
Date: Wed, 8 Jul 2015 22:18:23 -0400

>>   Configuration Option without configuration for the MPL domain.
...
> I agree with the fix. Thank you for suggestion.

That does correct the apparent contradiction, but it doesn't answer
one question I had, which seems to leave things uncertain:  Where the
text says, "A node SHOULD leave an MPL domain if it receives an
updated MPL Parameter Configuration Option without a configuration for
the MPL domain, unless it has overriding manual configuration on the
MPL domain," it's important to note that this still means that if you
*don't* have an overriding manual configuration on the domain, you
still SHOULD (not MUST) leave the domain.  That still means that you
could choose not to leave the domain.  Is that OK?

In other words:

1. You receive an updated MPL PCO without a config for the MPL domain.

1a. You *do* have an overriding manual configuration on the domain.
What are your choices?  I think you mean to say that your choices are
to stay on the domain or to leave it, at your option.

1b. You *don't* have an overriding manual configuration on the domain.
What are your choices?  I don't know whether you mean to say that you
MUST leave the domain in this case, or whether there might be other
reasons you might choose to stay, and the SHOULD is appropriate.

I'd still like an answer to those questions, so we can work out what
text will make that explicitly clear, and avoid confusion.  Do you see
why I'm uncertain?

Barry

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From: Yusuke DOI <[email-masked]>
Date: Wed, 08 Jul 2015 23:56:07 +0900

Hi Barry,

Thank you very much for kind review.

Yes, a device SHOULD not stay on the domain if current domain is not 
present in the MPL configuration update. However, even if it stays it 
does not break interoperability (just waste of resource). Thus I 
considered it's okay to stay on the domain if an implementation has 
strong reason to do so (the reason is beyond my imagination).

> or not I stay on the domain or leave it.  Is that correct?

A device SHOULD stay on domains that are manually configured. I think 
it's better to change the MAY to SHOULD.

>        address is present, or 32 if there is an MPL domain address.

Oops, thank you for pointing this out. there are no other choice.

Yusuke