----- Original Message -----
From: "Harald Tveit Alvestrand" <harald(_at_)alvestrand(_dot_)no>
Sent: Thursday, September 27, 2001 6:41 PM
Subject: Re: Exception to "MUST NOT"
--On 27. september 2001 09:32 +0900 Jiwoong Lee <porce(_at_)ktf(_dot_)com>
wrote:
MUST NOT means that you never do it, and any implementation that does it
is nonconformant to the spec.
If you find that you have to do it in some case, you have found a bug in
the spec.
Somecases. However, ICMPv6 example case, described in the first mail of
this thread, has not been found but already described in the spec; which
is not a bug at all.
could you give the RFC or draft name, and quote the text you are worried
about?
Yes. Please have a look on section 2.4 of RFC 2463 (ICMPv6)
...
(e) An ICMPv6 error message MUST NOT be sent as a result of
receiving:
...
(e.2) a packet destined to an IPv6 multicast address (there are
two exceptions to this rule: (1) the Packet Too Big
Message - Section 3.2 - to allow Path MTU discovery to
work for IPv6 multicast, and (2) the Parameter Problem
Message, Code 2 - Section 3.4 - reporting an unrecognized
IPv6 option that has the Option Type highest-order two
bits set to 10), or
(e.3) a packet sent as a link-layer multicast, (the exception
from e.2 applies to this case too), or
(e.4) a packet sent as a link-layer broadcast, (the exception
from e.2 applies to this case too), or
...
Jiwoong