Hello,
I'd like to know opinions on the following IAB recommendation
regarding rfc2462bis (the latter part):
e) We recommend that, via a recommendation to the IESG, that the IPv6
Working Group expeditiously revise RFC-2461 to:
* specifically note that it is not valid to configure an IPv6
router such that the 'autonomous configuration' bit is set to
TRUE AND the advertised IPv6 prefix length exceeds 64 bits AND
the advertised IPv6 prefix does not start with binary 000,
and also expeditiously revise RFC-2462 to:
* specifically require that a host ignore a Prefix Advertisement
Option when the first three bits of the advertised IPv6 prefix
do not start with binary 000 AND the advertised IPv6
prefix-length exceeds 64-bits.
(The entire message including the recommendation is available at:
http://www.iab.org/appeals/kre-ipng-address-arch-draft-standard-response.html)
The latest revision of the rfc2462bis draft does not contain this
particular change. In particular, it does not contain the hard-coded
constants of binary 000 and 64-bits.
Instead, the draft specifies a prefix (with the A flag being set) must
be ignored if the sum of the advertised prefix length and the length
of the interface identifier is not identical to 128. This requirement
is actually already included in RFC2452.
The rfc2462bis draft also clarifies that the length of the interface
identifier is defined in link-specific documents which should be
consistent with the IPv6 address architecture.
The above IAB recommendation is therefore a logical consequence from
what are described in the draft because the IPv6 address architecture
specifies the interface ID length is 64 for addresses beginning with
binary 000.
We could still add the specific recommendation to rfc2462bis.
However, I personally hesitate to do that since I basically prefer
not hard-coding particular constants in general rules as long as the
specification is clear (and, in fact, I believe the specification is
already pretty clear on this point).
What do others think? Any opinions or suggestions will be highly
appreciated.
JINMEI, Tatuya
Communication Platform Lab.
Corporate R&D Center, Toshiba Corp.
[EMAIL PROTECTED]
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