Unicast
Implemented between the sender and the receiver each point Fi. If one sender to multiple recipients simultaneously transmit the same data, it may also be multiple copies of the same corresponding replicated data packets . If there are a large number of hosts hope to get a packet when a copy of the same will result in a heavy burden on the sender, a long delay, network congestion ; in order to ensure a certain quality of service need to increase the hardware and the bandwidth .
broadcast
Broadcasting refers to the IP subnets within a broadcast packet , all subnets inside the host will receive these packets. Means that the network broadcast to each subnet hosts have delivered a packet, regardless of whether these hosts happy to receive the packet. Therefore, the use of broadcast is very small, only in the local subnet effective internal, through a router and a network device control broadcast transmission.
Multicast
Multicast realize multipoint network connection between the sender and each recipient. If a sender station to simultaneously transmit the same data to multiple recipients, and only a copy of the same packet. It improves data transfer efficiency and reduce the likelihood of backbone network congestion.
Multicast addresses the Unicast low and broadcast efficiency. When a user needs some specific information in the network, the multicast source (multicast sender) sends only one message, the multicast router by means of multicast routing protocol multicast packet tree route established, the information is passed duplicated or distributed in the fork eloquence as far as possible.
