Multicasting over IP networks
IP multicast is a protocol for transmitting IP datagrams from one source to many destinations in a local or wide-area network of hosts that run the TCP/IP suite of protocols.
Multicast and ATM Networks
Audio and video conferencing applications are very bandwidth-intensive, and require extremely low latency from the underlying network multicast service. IP can be run over increasingly fast links to solve the bandwidth problem, but there still remains a serious latency problem with IP networks. Stated simply, because IP can support very large packets, it is possible for a small, time-critical packet to get "stuck" behind a large packet. Multicast over ATM networks can address this problem.
The transfer of multimedia information streams between any source and destination of can occur in a number of different ways.
- Simplex: Information flows in one direction only.
- Half-duplex: Information flows alternately in both directions.
- Full-duplex: Information flows in both directions simultaneously.
- Unicast: Information flows from the source to a single destination.
- Multicast: Information flows from the source to multiple destinations, comprising a subset of the nodes connected to the network.
- Broadcast: Information flows from the source to all destinations connected to the network.
- Datagrams: A piece of a message transmitted over a packet-switching network. One of the key features of a packet is that it contains the destination address in addition to the data.In IP networks, packets are often called datagrams.
- Latency: In general, the period of time that one component in a system is waiting for another component to do its part. This wastes time and reduces performance. Examples include the time lag between the beginning of a request for data and the moment it begins to be received, or the time necessary for a packet of data to travel across a network.
- ATM: Asynchronous Transfer Mode is network technology based on transferring data in cells or packets of a fixed size. The small, constant cell size allows ATM equipment to transmit video, audio, and computer data over the same network, and assure that no single type of data hogs the line.