As in Parnes' proposal, we use RTP data packets as is, for data. The SSRC is the source VR application. More than one multicast group is used. Session messages are used within one multicast group to advertise the existence of participants and objects.
Objects have owners.
At any one time, the owner is the source of the session messages about an object. Messages can be marked as reliable or not reliable, however, this is not binding on recipients. Recipients can operate the repair algorithm on reliable object messages in the normal way.