SUBTREE_MCAST ?!

["Christoph Haenle" <christoph@starburstcom.com>]

Hello everybody,

does anyone know if there is support in current internet routers that would
make it possible for hosts ("designated receivers" within a multicast
hierarchy) to instruct a router to send a particular packet along the
multicast-tree that is rooted at the SENDER (rather than at the designated
receiver)?

For multicast-retransmission within a local group, I think this is a
required feature when a particular receiver is supposed to act as a
substitute for the sender. The designated receiver would then send the
repair packet to some nearby router in the multicast-tree and instruct him
to forward it along the that tree, so that it gets flooded in the very same
way as it would if it was sent by the multicast sender itself. The authors
of RMTP say/predict that there is/will be a new IP service (such as those
listed in /etc/services) called SUBTREE_MCAST that is essentially
IP-encapsulation with advise for the router to insert a fake source
address.

Anybody heard of this feature yet? Is there any router who supports this
feature? Is there any support in ns-2 for that?

     Thanks,

           Chris.