Apple QuickTime Streaming Server (Administrator’s Guide) - Manual (Page 10)

10 Preface
Multicast Versus Unicast
QTSS and DSS support both multicast and unicast network transport to deliver streaming
media.
In a multicast, a single stream is shared among the clients (see illustration). Each client “tunes
in” to the stream much as a radio tunes in to an FM broadcast. Although this technique
reduces network congestion, it does require a network that either has access to the multicast
backbone, otherwise called the Mbone, for content generally distributed over the Internet, or
is multicast enabled for content distributed within a contained private network.
In a unicast, each client initiates its own stream, resulting in the generation of many one-to-
one connections between client and server (see illustration). Many clients connected via
unicast to a stream in a local network can result in heavy network traffic. But this technique is
the most reliable for delivery over the Internet since no special transport support is required.
Multicast
Unicast
LL0329.book Page 10 Wednesday, November 20, 2002 2:09 PM