In the second method, the roles are essentially reversed. The dwFlags parameter is used to indicate whether the socket will be acting only as a sender, only as a receiver, or both. Only multipoint sockets may be used for input parameter s in this function. A multipoint root application is generally responsible for the orderly dismantling of a multipoint session. We chose these two as examples because they are very popular and well understood.
All applications play a leaf role.
The remaining three operations are covered well with the WinSock 2 semantics described here. Otherwise, an IGMP packet is sent out to the router to indicate interests in receiving packets sent to the specified multicast address. ATM Point to Multipoint ATM falls into the category of rooted data and rooted control planes. The leaf-initiated join is not supported in ATM UNI 3.1, but will be supported in ATM UNI 4.0.