All things related to multicast

[Hitoshi Asaeda <>]

> > >* Do existing IGMPv3 capable applications support Exclude mode for ASM
> >> groups?
> >
> >I don't think so.
> 
> Ok. So most of the times, applications will use one or multiple
> source addresses for ASM groups in INCLUDE mode. 

If you asked whether IGMPv3 applications can invoke (*,G) join/leave
(i.e. EXCLUDE mode join/leave without source address specification) in
ASM address range, of course it can.
I meant I've never heard and cannot imagine IGMPv3 capable
applications that invoke EXCLUDE mode join with source address
specification (i.e. EXCLUDE (S,G) join), whether in ASM address range
or not.
If you do want to specify multiple sources for a single group address,
you can specify them with INCLUDE mode join, whether in ASM address
range or not.

> >> * Also do anyone see a need for EXCUDE mode to be supported for their
> >> existing applications or any new applications they will create or like
> >> to use?
> >
> >I don't think there is necessity to use EXCLUDE mode for general
> >multicast applications, except some service discovery protocols, which
> >usually use (*,G). In other words, no use with source specific EXCLUDE
> >mode join/leave.
> 
> So EXCLUDE mode is typically used to allow all and never with a source list.

Yes, I think so.

> >>      I just wanted to know on how much this complex functionality
> >> ['Exclude Mode support'] being used in the field?
> >
> >I cannot imagine it'll be needed.
> >
> >In fact, eliminating EXCLUDE (S,G) join/leave is "beneficial" for
> >multicast communications. For example, it reduces host/router/switch
> >implementation costs and routing tree maintenance costs. It's not just
> >"unneeded". This is my thought.
> 
> Ok. I am also of the same opinion.
> 
> So with above assumptions, it looks like an IGMPv3 host/router part
> implementation or IGMPv3 snooping which does not handle EXCLUDE
> with source list should be able to work in multicast networks.

The better sentence is that supporting INCLUDE (S,G) join/leave
would contribute to multicast deployment in large networks.

Regards,
--
Hitoshi Asaeda