Re: about violation of standards - fe80::1/128

[神明達哉 <[e-mail]>]

At Wed, 24 Apr 2019 16:29:59 +0200,
Alexandre Petrescu <[e-mail]> wrote:

> As a response, I would like to ask whether fe80::1/128 on lo is a
> violation of standards.

First off, assuming you refer to the behavior of BSD variants
(including MacOS X), it's not 'lo' but 'loN' (normally just lo0 but
can also be lo1, lo2, etc, if these are also configured).  The world
doesn't only consist of Linux.

Secondly, again assuming it's BSD variants, it's not /128 but /64.

Third, I don't see which standard it might violate.  Could you be
more specific?

If you simply mean whether an implementation could choose to use ::1
as the mandatory link-local address on a loopback interface and skip
assigning an fe80 address on it, then I'd say it should be allowed as
we discussed off-list.  But IMO that would also require some update to
RFC4291, which is hopefully much less controversial than using a non-0
value in the intermediate 54-bit field.  And in any case, that doesn't
mean assigning an fe80 address on such an interface is a violation.

--
JINMEI, Tatuya