Multicast: membership to (*, G) group after leaving a (S, G) group

[Fabrice Colliot]

Sorry, I forgot to mention it. I've tried on FreeBSD 11.3 and FreeBSD 12.0.

/Fabrice

On Tue, Jul 7, 2020 at 1:48 PM Hans Petter Selasky <hps at selasky.org> wrote:

> On 2020-07-07 12:01, Fabrice Colliot wrote:
> > Hi,
> >
> > I'm using smcroute to join and leave multicast groups and I don't
> > understand the behavior of FreeBSD when the group is left.
> >
> > Here is what I do:
> >
> > smcroute join em1 10.3.4.5 224.0.55.55
> > ifmcstat -i em1
> > em1:
> >          inet 10.10.0.1
> >          igmpv3 rv 2 qi 125 qri 10 uri 3
> >                  group 224.0.55.55 mode include
> >                          mcast-macaddr 01:00:5e:00:37:37
> >                  group 224.0.0.1 mode exclude
> >                          mcast-macaddr 01:00:5e:00:00:01
> >
> > smcroute leave em1 10.3.4.5 224.0.55.55
> > ifmcstat -i em1
> > em1:
> >          inet 10.10.0.1
> >          igmpv3 rv 2 qi 125 qri 10 uri 3
> >                  group 224.0.55.55 mode undefined
> >                          mcast-macaddr 01:00:5e:00:37:37
> >                  group 224.0.0.1 mode exclude
> >                          mcast-macaddr 01:00:5e:00:00:01
> >
> > At this point, I expected to have no membership left on em1 for
> 224.0.55.55
> > but ifmcstat shows that the interface is still a member of the group but
> in
> > undefined mode.
> >
> > I was wondering if anybody could tell me why the group membership seems
> to
> > be transitioned to a (*, G) membership when all the (S, G) memberships
> are
> > removed.
> >
>
> Which version of FreeBSD is this?
>
> --HPS
>