Subject: a short comment on draft-okabe-ipv6-lcna-minreq-00.txt

From: JINMEI Tatuya / 神明達哉<[email-masked]>
Date: Sat, 17 Nov 2001 15:55:40 +0900

(I think the ipng ML is the best place to discuss the issue, but
please correct me if this is not appropriate.)

I've taken a quick look at draft-okabe-ipv6-lcna-minreq-00.txt and
have a short comment (or a question).

The draft says

2.3 Multicast
    Multicast is not treated in this draft, and it is the candidate for
    further study (RFC 2375[8], RFC 2710[9]). However, the multicast
    related to neighbor discovery is considered.   

So the minimum implementation must join some multicast groups for
neighbor discovery (e.g. solicited node groups).  This means the
implementation should perhaps support MLD, because there will be L2
switches that filter multicast packets unless the switches hear MLD
reports for the multicast group.  This will even be the case for
link-local groups, as in IPv4 multicasts.  Since MLD needs a
hop-by-hop router alert option, the implementation should support
the hop-by-hop options header as a consequence.

However, this draft also says

3.1.1 Hop-by-Hop Options Header
    [Sending]
    Following 3.1, minimum hosts do not send packets with this extension 
    header. 

This seems to contradict with the fact above.  I think the draft
should clarify this point.

					JINMEI, Tatuya
					Communication Platform Lab.
					Corporate R&D Center, Toshiba Corp.
					[email-masked]
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From: OKABE Nobuo <[email-masked]>
Date: Mon, 19 Nov 2001 10:51:43 +0900 (JST)

jinmei,

Thank you for your comment.

The draft assumes that a minimum host sends/receives
ND related link-local multicast without MLD,
and Hop-by-Hop Options Header is also unnecessary.

I'm not aware that L2 switch may drop the packets
without MLD as you mentioned.
But, how serious the problem is?

We developed a kind of minimum host
that is almost based on this draft, and
ran over a hundred of the hosts on a IPv6 network in N+I Tokyo 2001.
However, we have never seen the problem.

From: JINMEI Tatuya / 神明達哉 <[email-masked]>
Subject: a short comment on draft-okabe-ipv6-lcna-minreq-00.txt
Date: Sat, 17 Nov 2001 15:55:40 +0900

> should clarify this point.

---- nobuo

---

From: JINMEI Tatuya / 神明達哉<[email-masked]>
Date: Mon, 19 Nov 2001 21:37:19 +0900

>>>>> On Mon, 19 Nov 2001 10:51:43 +0900 (JST), 
>>>>> OKABE Nobuo <[email-masked]> said:

> But, how serious the problem is?

Please read my response to Cyndi.  I'm talking about future
implementation of L2 switches that support MLD snooping.  My concern
was partly (or 80%) wrong, which was due to a misunderstanding of
mine, but I'm still have a concern based on the current specification.

> However, we have never seen the problem.

Of course.  As far as I know, there is no L2 switch that support MLD
snooping at this moment.

					JINMEI, Tatuya