What are the characteristics of unicast, multicast and broadcast?

Unicast function: communication between a single sender and receiver through the network.

1. The server responds to the client's request in time.

2. The server sends different data according to different requests of each customer, which is easy to realize personalized service.

Multicast function: communication between a sender and multiple receivers.

Broadcasting features: "one-to-many" communication mode between hosts, the network unconditionally copies and forwards the signals sent by each host, and all hosts can receive all information (whether you need it or not).

1, simple network equipment, simple maintenance and low distribution cost.

2. Because the server does not need to send data to each client separately, the server traffic load is extremely low.

Extended data

Disadvantages of unicast

1. The server sends data streams for each client, and the server flow = number of clients × client flow; In streaming media applications with a large number of clients and a large flow of each client, the server cannot support such a huge data stream.

2. The existing network bandwidth is pyramid structure, and the bandwidth of intercity and inter-provincial trunk lines only accounts for 5% of the sum of all its users' bandwidths. If all unicast protocols are used, the network backbone will be overwhelmed.

The basic concept of multicast is "group". A multicast group is a group of recipients who want to receive a specific data stream. This group has no physical or geographical boundaries: the hosts in the group can be located anywhere on the Internet or private network.

In many multicast applications, unicast can be realized, but with the increase of receivers, the number of packets to be sent increases linearly. For each receiver, N copies of the same data packet need to be sent, so the traffic will increase exponentially, and it will also occupy a lot of network bandwidth, sometimes causing network congestion.

However, multicast IP packets are sent only once. The router will automatically forward it to each receiver on different network segments, which can minimize the number of message copies transmitted in the network. So multicast is necessary.

References:

Baidu encyclopedia-unicast