All things related to multicast

[Toerless Eckert <>]

John, a host can not join to (*,G) and (S,G) with IGMPv3.
Blame IGMPv3 to be a broken protocol, but basically you
can either do an EXCLUDE({},G) membership (aka join (*,G))
or an INCLUDE({S},G) (aka join (S,G)). Remember: IGMPv3
allows you to only report INCLUDE or EXCLUDE mode for a group !

Yes, with IGMPv3lite we can do this ;-))

Cheers
        Toerless

Unless you come up with a completely twisted IGMP 
If a host does an IGMP 
On Tue, May 14, 2002 at 11:23:31AM -0700, John Zwiebel wrote:
> Toerless Eckert wrote:
> > 
> > On Tue, May 14, 2002 at 07:27:30AM -0400, Marshall Eubanks wrote:
> > >
> > > I must admit that as a practical matter, I am dubious about the effacy 
> > > of just
> > > treating ASM sessions as if they were SSM. The two were deliberately 
> > > intended
> > > not to interoperate at the group level, and it seems like a kludge to 
> > > treat them
> > > as if they were.
> > >
> > > Marshall
> > 
> > Please explain.
> 
> FWIW:
> I suggested to him that if the source was included in the
> SAP description that a host could decide for itself
> whether it wanted to join (*,G) or (S,G) allowing
> him to use a single source to satisfy both SSM and ASM.
> 
> Since some vendor implementations will have the last hop
> join to the (*,G) as well as the (S,G) on receipt of
> an IGMPv3 report, and for many other reasons, his 
> reluctance to follow this suggestion is valid.  I 
> totally agree that doing this is a kludge.
> 
> But then so was MSDP, any-cast RP, and IGMP snooping.
> 
> If the community wants to stay "virgin" and keep ssm
> only in the 232/8 range (ie there is 'virgin SSM' and
> 'compromised SSM' which would be to implement my 
> kludge.) that's fine with me.  There are probably
> many reasons to do so.
> 
> OTOH, there's no reason to not use the kludge.  It
> doesn't result in any interoperability problems and
> it does get packets to the receiver without having to
> depend on MSDP.  So, I'm happy to leave it up to the
> content provider and the receiver to make the 
> choice about whether or not they want to maintain 
> their virginity.
> 
> z

-- 
Thanks
   Toerless Eckert