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

[Fernando Gont <[e-mail]>]

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.

Thanks!

Best regards,
-- 
Fernando Gont
SI6 Networks
e-mail: [e-mail]
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