There are three types of Message Transmission Methods on an IP network. Each type is designed for a specific purpose. The three types are:
Unicast messages are sent from one device to another device. Unicast messages have on sender and one receiver. A unicast message is the equivalent of a private conversation between two people.
Broadcast messages are sent from one point to all other points. A broadcast has one sender and every other device is a receiver. A broadcast message would be the equivalent of a speaker at a function.
Multicast message are sent between a set of devices. Multicast messages have a set of senders and receivers. A multicast message would be the equivalent of a conference call where there are participants and non-participants.