Multicast

A multicast is a transmission of knowledge from a single supply to a number of recipients. Multicasting is just like broadcasting, however solely transmits info to particular customers. It is used to effectively transmit streaming media and different forms of knowledge to a number of customers at one time.

The easy approach to ship knowledge to a number of customers concurrently is to transmit particular person copies of the info to every consumer. However, that is extremely inefficient, since a number of copies of the identical knowledge are despatched from the supply via a number of networks. Multicasting allows a single transmission to be break up up amongst a number of customers, considerably lowering the required bandwidth.

Multicasts that happen over the Internet are referred to as IP multicasts, since they use the Internet protocol (IP) to transmit knowledge. IP multicasts create “multicast trees,” which permit a single transmission to department out to particular person customers. These branches are created at Internet routers wherever obligatory. For instance, if 5 customers from 5 totally different nations requested entry to the identical stream, branches can be created near the unique supply. If 5 customers from the identical metropolis requested entry to the identical stream, the branches can be created near customers.

IP multicasting works by combining two different protocols with the Internet protocol. One is the Internet Group Management Protocol (IGMP), which permits customers or shopper techniques use to request entry to a stream. The different is Protocol Independent Multicast (PIM), which is utilized by network routers to create multicast timber. When a router receives a request to affix a stream through IGMP, it makes use of PIM to route the info stream to the suitable system.

Multicasting has a number of totally different functions. It is often used for streaming media over the Internet, similar to dwell TV and Internet radio. It additionally helps video conferencing and webcasts. Multicasting may also be used to ship different forms of knowledge over the Internet, similar to information, inventory quotes, and even digital copies of software program. Whatever the applying, multicasting helps scale back Internet bandwidth utilization by offering an environment friendly method of sending knowledge to a number of customers.