What is Multicast?
Multicast is the delivery of information to a group of destinations simultaneously using the most efficient strategy to deliver the messages over each link of the network only once, creating copies only when the links to the destinations split. The word “Multicast” is typically used to refer to IP Multicast, the implementation of the multicast concept on the IP routing level, where routers create optimal spanning tree distribution paths for datagrams sent to a multicast destination address in real time. But there are also other implementations of the multicast distribution strategy listed below.
Information is delivered over a network by three basic methods: unicast, broadcast, and multicast. The differences among unicast, broadcast, and multicast can be summarized as follows: • Unicast: One-to-one, from one source to one destination. • Broadcast: One-to-all, from one source to all possible destinations. • Multicast: One-to-many, from one source to multiple destinations expressing an interest in receiving the traffic. Note: This list does not include a special category for many-to-many applications, such as online gaming or videoconferencing, where there are many sources for the same receiver and where receivers often double as sources. Many-to-many is a service model that repeatedly employs one-to-many multicast and therefore requires no unique protocol. The original multicast specification, RFC 1112, supports both the any-source multicast (ASM) many-to-many model and the source-specific multicast (SSM) one-to-many model. With unicast traffic, many streams of IP packets that
Multicasting is a communication process that takes place in a network environment. Essentially, a multicast is a message that originates with a single user and is received by multiple end points around the network. In a sense, a multicast is somewhat like sending a single email out to various email addresses. However, the key difference is that a multicast does not rely on any type of email addressing or software, and the transmission is confined to users that are connected to the single network. There are many different applications that may employ the use of multicast. One common use of the technology is to quickly and easily forward time sensitive announcements out to key people within the organization. Unlike an email transmission, the multicast is not forwarding a message out from a server, across a range of providers and networks, and then terminating in a mailbox. The announcement is delivered to the various points of termination in real time, and will appear as a dialogue box o
