Unicast, multicast, and broadcast happen at layer-2 and layer-3. Remember layer-2 is the data-link layer where the switch device works using the MAC addresses for communication, and layer-3 is the network layer where the router device works using the IP addresses for communication.
Here, “cast” refers to how many people or devices we send the data to. It can be unicast, multicast, or broadcast. These 3 methods are the types of communication, used to transmit packets over a network.
- Unicast means one-to-one, data send to only one device means sender sends data to only one device.
- Multicast means one-to-many (or many-to-many), data sent to multiple devices means sender sends data to many devices (not all devices like the broadcast).
- Broadcast means one-to-all, data sent to all devices means sender sends data to all devices.
Table of Contents
What is Unicast?
In a Unicast transmission, data is sent from a single sender to a single receiver. This means that every packet is addressed to a specific device on the network. Unicast is used for point-to-point communication, where a single device needs to communicate with another device.
In computer networking, Unicast is a term, that is used when data is transmitted from one point to another point.
It is a one-to-one communication; that is one sender and one receiver. when one device transmits the data to another device then it is called unicast transmission. Generally, we use one-to-one communication on our daily basis like- sending a message, browsing a website, downloading a file, etc.
Some Examples:
- Ex-1: A device having an IP address 20.1.3.0 in a network wants to transmit the data to the device with IP address 30.10.5.0 in another network, then this transmission is called Unicast transmission.
- Ex-2: There are 4 computers connected to the switch device, so if pc1 wants to communicate with pc2, then they can directly communicate with each other so this is unicast communication because it is one-to-one communication.
- Ex-3: Browsing a website is also unicast communication, where the web server acts as a sender and our computer acts as a receiver.
- Ex-4: Downloading a file from an FTP server is another example of unicast transmission, where the FTP server acts as a sender and our computer acts as a receiver.
What is Multicast?
Multicast is a type of data transmission where data is sent from one device to a group of devices on a network.
It is a type of one-to-many communication, where a single packet of data is transmitted to multiple recipients simultaneously.
In a Multicast transmission, a single packet is addressed to a group of devices, rather than to a single device like in Unicast. The packet is then replicated and sent to all devices in the group, which allows for more efficient use of network resources.
In a Multicast transmission, every packet is addressed to a multicast group address. This means that only devices that have subscribed to the multicast group will receive the packet.
Multicast transmission is widely used in applications such as video streaming, online gaming, and real-time communication, where the same data needs to be sent to multiple recipients at the same time. For example, in a video streaming application, a video stream is sent to a group of users who are all watching the same video.
What is Broadcast?
Broadcast is a type of data transmission where data is sent from one device to all devices on a network.
In a Broadcast transmission, every packet is addressed to the broadcast address of the network. This means that every device on the network will receive the packet.
It is a one-to-all transmission means there is one sender, but the information is delivered to all the connected receivers.
Broadcast is used for scenarios where a single device needs to communicate with all devices on a network.
This term “broadcast“, mostly used in cable TV transmission. TV signals are sent from one source (one point) to all the possible destinations (all points).
There are two types of broadcast transmission in computer networks: limited broadcast and directed broadcast.
Limited Broadcasting
- Sends a packet to all devices on the local network segment
- Uses a special IP address called the limited broadcast address (255.255.255.255)
- Recognized by all devices on the local network
- Packet is not forwarded by routers, so it remains within the local network segment
Direct Broadcasting
- Information directly sends to all the devices on other network.
- When a device in one network transfer data packet stream to all the devices on the other network, it is referred to as direct broadcasting.
You should also read: Data Transmission Modes