Using multicast, one host can send a data packet to thousands of nodes over a routed network. IP multicast can scale to a large number of recipients because the server does not need to know the identity or number of destinations. This distinguishes this approach from traditional TCP/IP communication, which requires a separate connection for each source-destination pair.
How does IP multicasting work?
IP multicast is used to transmit data to multiple nodes. Nodes, such as routers and switches, allow data packets to be copied to be sent to recipients so that they are transmitted on each channel only once. This method is implemented in three ways:
- IP multicasting group address
- tree controlled by the receiver
- multicast distribution tree.
IP multicast is used by sources and recipients for messaging. They use a group address to send their packets – the destinations ask the network to join it using IGMP.
This method of sending data to a multicast group is more efficient than unicast and broadcast methods. In unicast, the sender sends data to each recipient in the multicast group separately, which makes it very inefficient with a large number of destinations.
On the other hand, in the broadcast method, the sender transmits the data to each node in the network, and the nodes that do not need the data simply discard it. This consumes resources and only applies to nodes within the same network or LAN.