Unicast and Multicast
There are two basic streaming architectures: unicast and multicast. Unicast streaming involves a one-to-one (point-to-point) connection between a server and a client; each client gets a unique data stream, and only those clients that request the stream will receive it. Unicast streaming works either for live streaming or on-demand streaming. The number of participants is limited by the bit rate of the video content being streamed, the speed of the server, and the bandwidth of the network conduit.
Multicast streaming involves a one-to-many relationship between the codec and the clients receiving the stream; all clients receive the same stream by subscribing to a designated multicast IP address. A virtually unlimited number of users can connect to a multicast stream. Because a single data stream is delivered simultaneously to multiple recipients, it reduces the server/network resources that would be needed to send out duplicate data streams. A network must be properly configured for multicast streaming, however. Depending on a network’s infrastructure and type, multicast transmission may not be a feasible option.