(usagi-users 02906) Re: IPv6 Multicast on recent Linux Kernels

[Stig Venaas <Stig.Venaas@xxxxxxxxxx>]

On Wed, Apr 14, 2004 at 01:38:05PM -0700, David Stevens wrote:
> Nicholas Humfrey <njh@xxxxxxxxxxxxxxx> wrote on 04/14/2004 11:16:03 AM:
> 
> > The symptoms are that it is unable to join Multicast groups, however
> > if there is another machine on the subnet, already a member of the
> > group, then it picks up the packets ok. Linux will also will remain a
> > member of the multicast group, even with the other machine leaves.
> 
> Are you running a multicast router? Do the other machines on the network
> have the same ICMPv6 "type" code for reports (206) ? This number isn't
> assigned by IANA last I checked, so implementations had to choose a 
> number--
> won't interoperate if they aren't using the same one.

IANA now lists it! It says:
143  Version 2 Multicast Listener Report              [RFC-vida-mld-v2-08.txt]

I think this must have happened just a few days ago. So perhaps we can
change then? Some implementations are already using 143. Don't know what
FreeBSD does.

> Also, you could try reverting to MLDv1 by:
> 
> sysctl -w net.ipv6.conf.eth0.force_mld_version=1

I thought that if Linux uses 206 and the router something else, that
Linux should revert to MLDv1, but I checked the spec now, and it seems
this is not the case. The router only sends MLDv1 queries if it has
seen MLDv1 report. Linux (the host) only sends v1 reports if it has
seen MLDv1 query (or it only support v1 of course). I believe the spec
works fine what it's intended to solve. It appears not to help in this
case.

Stig