Re: RFC4291bis

[神明達哉 <[e-mail]>]

At Wed, 8 Aug 2018 11:39:23 +1200,
Brian E Carpenter <[e-mail]> wrote:

> Assuming that we adopt draft-farmer-6man-exceptions-64
> for the standards track or BCP, I suggest that we should
> also update draft-ietf-6man-rfc4291bis as proposed below,
> and plan for the two documents to be published as RFCs
> simultaneously:

I don't see how we can suddenly agree on publishing rfc4291bis as an
IS with keeping the most controversial text just with some new wording
tweak and a reference to draft-farmer-6man-exceptions.  In fact, if it
were possible, I suspect we could even do that without a new document
(i.e., 6man-exceptions).

To this end I wondered how we failed with
draft-ietf-6man-rfc4291bis-09 and have skimmed the discussion at that
time starting from:
https://www.ietf.org/mail-archive/web/ipv6/current/msg27919.html
and found the following controversial points:

- the word "by exceptions defined in standards track documents" (see
  also my recent message to the draft-farmer-6man-exceptions thread)
- referring to a specific way of configuring addresses (in particular
  SLAAC) from the Addressing *Architecture* document.

The proposed new text still has these two points.  I'd be pessimistic
about the odds for "this time is different" just because of this fact.

> NEW:
>    Interface Identifiers for stateless address autoconfiguration
>    are 64 bits long except if the first three bits
>    of the address are 000, or when the addresses are manually
>    configured, or by exceptions defined in standards track documents.
>    The rationale for using 64 bit Interface Identifiers can be found in
>    [RFC7421].  An example of a standards track exception is [RFC6164]
>    that standardises 127 bit prefixes on inter-router point-to-point
>    links. The relationship between prefix length and Interface Identifier
>    length is discussed in [I-D.farmer-6man-exceptions-64].
>
>       Note: In the case of manual configuration, the Prefix and
>       Interface Identifier can be any length as long as they add up to
>       128. In all cases, routing and forwarding processes must be
>       designed to process prefixes of any length up to /128 [BCP198].

--
JINMEI, Tatuya