CH A P T E R
IP Multicast Overview
IP multicast allows for a streamlined approach to data delivery whenever multiple hosts need to receive the same data at the same time. For example:
When configured for IP multicast services, Music-on-Hold (MoH) can stream the same audio file to multiple IP phones without the overhead of duplicating that stream one time for each phone on hold.
IP/TV allows for the streaming of audio, video, and slides to thousands of receivers simultaneously across the network. High-rate IP/TV streams that would normally congest a low-speed WAN link can be filtered to remain on the local campus network.
Multicast vs. Unicast
Multicast behaves differently than unicast. Unicast allows users to gain access to their “own” stream of data. The drawback to unicast is its inefficiency in distributing the same stream of data to multiple users. When a data stream from a single source is sent to many receivers using a unicast transmission, a load is created not only on the source but also on the network itself. The stream must be copied once for each user across the network. Figure 1-1 illustrates this difference.
Cisco AVVID Network Infrastructure IP Multicast Design