Subject: RE: ICMPv6 echo reply to multicast packet thread

From: Suresh Krishnan <[email-masked]>
Date: Thu, 11 Mar 2004 23:53:05 -0500 (EST)

On Thu, 11 Mar 2004 [email-masked] wrote:

>Now, who can tell if multicast echo request is the primary 
>multicast debugging mechanism or not ??

Since there is no alternate mechanism, this has become the primary and 
preferred multicast debugging mechanism. If some mechanism is proposed 
which is better and is less liable to be misused, it will become the 
primary mechanism. The KAME project was working on a multicast traceroute
tool for IPv6 a while ago. I have not personally used it. Probably 
Jinmei can comment further on this.

Regards
Suresh

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From: Stig Venaas <[email-masked]>
Date: Fri, 12 Mar 2004 14:31:47 +0100

> Jinmei can comment further on this.

Especially pinging ff02::1 is often used not just for debugging
multicast, but also for other debugging. So I think this is useful,
even if some other multicast debugging mechanisms are introduced.

Stig

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From: Hoerdt Mickael <[email-masked]>
Date: Fri, 12 Mar 2004 14:45:12 +0100 (CET)

Hello,

Allowing or not allowing a reply to a icmpv6 multicast request message is
an interesting question.

Now I am wondering why it is not allowed to answer to such a message in
IPv4 (=> http://www.icir.org/fenner/mcast/icmp.html) and allowed in IPv6 ?

Thank you,

Hoerdt Mickael
LSIIT Laboratory

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From: Pekka Savola <[email-masked]>
Date: Fri, 12 Mar 2004 16:36:26 +0200 (EET)

> IPv4 (=> http://www.icir.org/fenner/mcast/icmp.html) and allowed in IPv6 ?

Uhh -- it's fine to answer an ICMP echo request, but you should not 
send ICMP errors bassed on v4 packets.  The same general principle 
applies to v6 as well -- with the exception that options formed in a 
certain way still require a reply.  This could be an attack vector in 
the future, if multicast were to be used in the large scale.

-- 
Pekka Savola                 "You each name yourselves king, yet the
Netcore Oy                    kingdom bleeds."
Systems. Networks. Security. -- George R.R. Martin: A Clash of Kings

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From: JINMEI Tatuya / 神明達哉 <[email-masked]>
Date: Fri, 19 Mar 2004 23:37:53 +0900

>>>>> On Thu, 11 Mar 2004 23:53:05 -0500 (EST), 
>>>>> Suresh Krishnan <[email-masked]> said:

> Jinmei can comment further on this.

Our experimental implementation of multicast traceroute for IPv6 is
described in a paper available at the following URL:
http://www.isoc.org/isoc/conferences/inet/00/cdproceedings/1c/1c_2.htm

But in any event, I don't think it helps this particular discussion.
It's just experimental, and I've even never written an I-D on this
(partly because the standardization of IPv4 multicast traceroute has
been pending).

For the original discussion, I agree with Pekka; I prefer to (continue
to) allow responding to multicasted echo requests by default, for
almost the same reasons he provided.

					JINMEI, Tatuya
					Communication Platform Lab.
					Corporate R&D Center, Toshiba Corp.
					[email-masked]