In the tunneling approach, routers can be statically associated with one another, acting as if they are participating over a direct link. In weak encapsulation, source-based routing is used to forward both control traffic, as well as multicast traffic. Control information is sent over the tunnel route as unicast datagrams are directed to the far end-point of the tunnel. The flooding required by the routers to manage the routes can aggregate into large amounts of traffic required for information exchanges and for the transmission of packets through the network prior to pruning of the multicast tree. As a member of the distance vector routing family, timers need to be tuned to re-learn routes.
Oscillations strongly interfere with that behavior.
It has been in use for over a decade, providing useful services, and has also served as a foundation for research into multicast routing.