Re: I-D Action: draft-ietf-6man-default-iids-04.txt

[Kerry Lynn <[e-mail]>]

On Mon, Jul 6, 2015 at 12:50 PM, Fernando Gont <[e-mail]>
wrote:

> Hi, Kerry,
>
> On 07/06/2015 01:26 PM, Kerry Lynn wrote:
> >     Could you please take a look at Mark's comment and rationale, and
> vice
> >     your opinion?
> >
> >     He essentially argues that we should remove the "MAY" in:
> >      "It is RECOMMENDED by this document that future specifications do
> not
> >       specify IPv6 address generation schemes that embed the underlying
> >       link-layer address in the IID.  Future specifications MAY use an
> IID
> >       based on a node's link-layer address if design and engineering
> >       considerations warrant."
> >
> >     (his rationale is provided below).
> >
> >     I'm fine with applying his suggested change, but would like to hear
> your
> >     thoughts before applying any changes.
> >
> > As the lead author of
> > https://tools.ietf.org/html/draft-ietf-6man-6lobac, I'm
> > strongly in favor of retaining the option to specify IIDs based on
> locally
> > assigned link-layer addresses, particularly for link-local addresses.
>
> FWIW, this has never been under question. That is, the question is
> regarding the wording, not about the intent. Based on past wg discussion
> and consensus, we all agree that there must be room to go against this
> advice if design/engineering tradeoffs warrant this.
>
>
> > The first sentence in the paragraph above could be interpreted as
> > recommending that authors of future proposals MUST NOT provide a
> > specification for forming IIDs from link-layer addresses.  The MAY
> > in the following sentence makes it clear that the recommendation is
> > SHOULD NOT.
>
> Well... a "SHOULD NOT" is a "SHOULD NOT". IF somene can read a "SHOULD
> NOT" as a "MUST NOT", then we should refer them to RFC2119. I think the
> issue that MARK raises is more tricky, since the MAY itself might lead
> to some confusion.
>
> I'm afraid I was a few emails behind in the thread.  I agree that Mark's
proposed

  "Future specifications SHOULD NOT specify IPv6 address generation
   schemes that embed the underlying link-layer address in the IID."

is clearer, although it remains silent on when it is permissible to specify
such
schemes (and perhaps intentionally so).

Cheers, Kerry

 Thanks!
>
> Best regards,
> --
> Fernando Gont
> SI6 Networks
> e-mail: [e-mail]
> PGP Fingerprint: 6666 31C6 D484 63B2 8FB1 E3C4 AE25 0D55 1D4E 7492
>
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