All things related to multicast

[Stig Venaas <>]

Bharat Joshi wrote:
> Hi Hitoshi,
>
>      Thanks for you response. Please see my response in line.
>
> Regards,
> Bharat
>
> > > * 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.
>
> > > * 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.

While I don't know any applications, it might be useful for say
conferencing to exclude sources for muted participants.

Stig

> > >      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.
>
> **************** CAUTION - Disclaimer *****************
> This e-mail contains PRIVILEGED AND CONFIDENTIAL INFORMATION intended solely 
> for the use of the addressee(s). If you are not the intended recipient, 
> please notify the sender by e-mail and delete the original message. Further, 
> you are not to copy, disclose, or distribute this e-mail or its contents to 
> any other person and any such actions are unlawful. This e-mail may contain 
> viruses. Infosys has taken every reasonable precaution to minimize this risk, 
> but is not liable for any damage you may sustain as a result of any virus in 
> this e-mail. You should carry out your own virus checks before opening the 
> e-mail or attachment. Infosys reserves the right to monitor and review the 
> content of all messages sent to or from this e-mail address. Messages sent to 
> or from this e-mail address may be stored on the Infosys e-mail system.
> ***INFOSYS******** End of Disclaimer ********INFOSYS***