Windows Sockets 2 Interface Elements for Multipoint and Multicast

The mechanisms that have been incorporated into Windows Sockets 2 for utilizing multipoint capabilities can be summarized as follows:

Three attribute bits in the WSAPROTOCOL_INFO struct

1. Four flags defined for the dwFlags parameter of WSASocket
2. One function, WSAJoinLeaf, for adding leaf nodes into a multipoint session
3. Two WSAIoctl command codes for controlling multipoint loopback and the scope of multicast transmissions.

The paragraphs which follow describe these interface elements in more detail.