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

[Yusuke DOI <[e-mail]>]

Hi Barry,

Thank you very much for kind review.

On 2015-07-08 3:18, Barry Leiba wrote:
> ----------------------------------------------------------------------
> DISCUSS:
> ----------------------------------------------------------------------
>
> 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?

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).

> 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?

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

> "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.

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

Yusuke