[ih] IPv8...

[John Kristoff]

On Tue, 21 Apr 2026 11:46:51 -0400
John Day <jeanjour at comcast.net> wrote:

> I presume there then has to be some method for notifying stations and
> links that they should be willing?

Yes, this has most commonly involved IGMP and PIM.  IGMP for hosts and
routers to report and learn group membership on a link.  PIM to
construct the forwarding path overlay (basically you route away from
the source where there are interested receivers).

> Seems to be an unnecessary complication.

Not sure about unnecessary, but a complication... yes sir, especially
for inter-domain deployment, which has largely been abandoned by most
networks.  You still find deployments within certain environments for
mass OS imaging, IP TV, and the stock-ticker sort of applications.

> (Applications shouldn’t have to specifically request multicast. The
> provider determines whether to simply send n copies or use multicast.
> It is the provide that benefits, not the application.)

As implemented a host needs to know to listen on the group address and
it needs to signal the network there is a group listener.  I'd guess if
you don't want the OS/app involved there would need to be some sort of
proxy near group members that perform all this.  This is probably close
enough to what CDNs do already.

John