Transmission in a computer network is in fact the process of sending a packet from one host to one or more others connected to the network. The difference between Unicast Multicast and Broadcast is very important to know. The terms Unicast, Multicast and Broadcast are also the communication modes. So, in this article, we will look at these different terms together and make a differentiation.
Unicast
Unicast defines a point-to-point network connection, which is a one-to-one communication method.
In addition, unicast means communication between two computers, each identified by a unique network address. The data packets are routed on the network according to the recipient’s address “encapsulated” in the transmitted frame. Therefore, only the recipient intercepts and decodes the packet that is normally addressed to him.
However, Unicast addresses represent a single LAN interface. A unicast frame will then be sent to a specific device, not to a group of devices on the LAN.
The diagram below illustrates the Unicast communication method:
Multicast
Indeed, multicast is a form of broadcasting from a transmitter (single source) to a group of receivers. The terms “multipoint broadcast” or “group broadcast” are also used. It is therefore a one-to-many communication method.
However, multicast addresses represent a group of devices in a LAN. A frame sent to a multicast address will therefore be transmitted to a group of devices on the LAN.
The diagram below illustrates the Multicast communication method:
Broadcast (or diffusion)
Broadcast is therefore a transmission technology that allows all hosts connected to a network to share the same communication channel. In Broadcast, a packet sent by a host is then received by all other hosts on the network. It is therefore a one-to-many communication method.
Then the broadcast addresses represent all the devices on the LAN. And the frames sent to a broadcast address will therefore be delivered to all devices on the LAN.
The diagram below illustrates the Broadcast communication method:
Difference between Unicast, Multicast and Broadcast
| Unicast | Multicast | Broadcast |
| Communication: one-to-one. | One-to-many. | One-to-all. |
| A sender and a receiver on the network. | One sending host and several receiving hosts on the network. | One sender and all recipients on the network. |
| Very fast process. | Fast. | Heavy. |
| Bandwidth: very efficient. | Efficiently. | Wasted. |
