Subject: [magma] MLD joins for link-local-scope ?

From: Toerless Eckert <[email-masked]>
Date: Tue, 28 Jun 2005 08:30:58 -0700

-> Remind me: Why is there no real strong language in rfc3590 to
   state that the host must generate MLD membership reports for
   all groups joined to on the interface ... including link-local scope
   group ? (I could only find the notion of the inversion in the introduction
   "of scope less than 2", and in the rest of the text it just states
   "all multicast addresses joined on the interface", and the reader has
   to remind himself of the IPv6 address architecture that this implies
   scope of 2 or larger ?)

-> Does anyone have data from host stacks to state that there are or
   are not hosts stacks not sending MLD joins for link-local scope groups ?

Thanks
    Toerless

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From: Brian Haberman <[email-masked]>
Date: Wed, 29 Jun 2005 07:55:25 -0400

>    to remind himself of the IPv6 address architecture that this implies

I think 3590 is the wrong place to look for such language.  That RFC
was written simply to clarify the use of :: as a source address for the
sending of MLDv1 messages prior to performing Duplicate Address
Detection.  It is not the place to levy behavioral requirements on MLD.
Given that it only applies to MLDv1 (RFC 2710), I would think that you
need to look at whether MLDv2/IGMPv3 have stronger language for
this requirement.  However, I see in section 6 of RFC 3810 that there
is no real RFC 2119-style requirements for sending Reports for all
groups joined other than the all-nodes address.

>    are not hosts stacks not sending MLD joins for link-local scope 

I am not aware of any host stacks that send Reports for their 
solicited-nodes
multicast addresses.  Though that data point is a year or so old.

Regards,
Brian

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From: Pekka Savola <[email-masked]>
Date: Wed, 29 Jun 2005 15:27:31 +0300 (EEST)

On Wed, 29 Jun 2005, Brian Haberman wrote:
> I am not aware of any host stacks that send Reports for their solicited-nodes

Looking at KAME and Linux, it seems they do send the reports on 
solicited-nodes multicast addresses as well.

-- 
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: SUZUKI Shinsuke <[email-masked]>
Date: Wed, 29 Jun 2005 01:09:50 +0900

Hello Toerless,

>>>>> On Tue, 28 Jun 2005 08:30:58 -0700
>>>>> [email-masked](Toerless Eckert)  said:

>    to remind himself of the IPv6 address architecture that this implies

RFC2710(sec.5, p.10) already says link-local scope is the target of
MLD join, except for ff02::1. (and RFC3810(sec.6 p.27) as well)

  > [a description in RFC2710 section5 p.10]
  >   MLD messages are never sent for multicast addresses whose scope is 0
  >   (reserved) or 1 (node-local).
  >
  >   MLD messages ARE sent for multicast addresses whose scope is 2
  >   (link-local), including Solicited-Node multicast addresses [ADDR-
  >   ARCH], except for the link-scope, all-nodes address (FF02::1).

RFC3590 is a clarification to RFC2710 regarding only on source address
selection, so I don't think this RFC has to mention this point again.

>    are not hosts stacks not sending MLD joins for link-local scope

I've joined several IPv6 interoperability testing events and checked
the behavior of MLDv1/v2 host implementations.  So far, I haven't
found an IPv6 host implementation ignoring that rule.

Thanks,
----
SUZUKI, Shinsuke @ ALAXALA Networks / KAME Project