Multicast is the process of sending data to several users simultaneously. The data sent can be in audio, video, image, or any other format. In multicast communication, only one data source or sender communicates with multiple receivers. Multicast is a one-way communication model, so the receivers can’t send data back to the source.

Regular Internet users have taken advantage of this technological process by simply sending an email to multiple email addresses. Some industries have taken multicast to a more advanced level. For example, multicast communication allows the one-time delivery of vehicle geolocation data to all connected cars instead of sending the same data multiple times.

Read More about Multicast

Multicast is a mode of communication that is quite useful in several technological areas and a wide range of industries. We dove into the basic concepts related to multicast below.

What Are the Differences between Unicast, Multicast, and Broadcast?

Unicast communication occurs when data travels from one device to another on the same network. Only one sender and one receiver interact. Watching YouTube or Netflix videos is an example of unicast communication. The on-demand streaming service only relays data to the user who requested to see the selected video.

On the other hand, broadcast communication sends data from one device to all devices on the network. Television and radio shows are classic examples of broadcast communication models since a TV or radio station transmits data to all devices, regardless of the receiver’s preference. Even when the TV owners don’t want to watch a particular show, it would still be shown on their devices if they happen to switch to the channel.

Multicast communication comes between unicast and broadcast. It is the process of sending data from one device to a selected group of devices within a network. For this reason, multicast is also called “one-to-many communication.”

The image below captures the fundamental difference between unicast, multicast, and broadcast.

what is multicast

How Does Multicasting Work?

Multicast communication starts with a server that aims to send data packets to several recipients. The receiving devices must use an IP address belonging to the IP range designated for multicast traffic, which is 224.0.0.0 to 239.255.255.255.

When the router receives the multicast traffic, it needs the Internet Group Management Protocol (IGMP) mechanism to determine which connected devices want to receive the data. IGMP is a communication protocol that enables networked devices to establish a multicast group.

What Are Some Examples of Multicast?

Aside from intelligent cars that we previously cited, here are a few real-life examples of how multicast communication is used.

  • Stock ticker: Multicast sends stock market information to the stock ticker, which is automatically displayed on the screen.
  • Digital billboards: Advertising managers can change the content of selected billboards by sending graphics data over a multicast network. That way, ad managers can select which graphics are shown, depending on the billboard’s location. 
  • Internet Protocol television (IPTV): Multicast communication is used to deliver TV content to viewers over IP networks. The video content sender delivers the data in one stream instead of using multiple streams to reach different receivers.

What Are the Advantages and Disadvantages of Multicast?

One of the most significant advantages of multicast is scalability. It can cater to a vast number of receivers without overloading the source server or compromising network performance. It does not force devices to receive multicast traffic and process unwanted data packets.

Multicast network communication is not bandwidth-intensive since the sender only delivers a single data stream to multiple receivers. Not using multicast would require the sender to deliver multiple streams, taking up bandwidth.

There are also downsides to using multicast—the need for applications with multicast support being the primary one. While it is widely used now, multicast is still not the default mode of communication devices and networks use. Therefore, we have to configure systems so they can support multicast.

Arising from the need for multicast applications is the issue of reliability, which can only be as good as the application used.

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While multicast has helped remove the negative advantages of unicast and broadcast, several vital network processes continue to use the other two communication modes.

Key Takeaways

  • Multicast is a mode of network communication where a sender transmits the same traffic to multiple receivers.
  • Multicast is also known as “one-to-many communication.”
  • Other modes of communication are unicast (i.e., data is transmitted to only one receiver) and broadcast (i.e., data is sent to all networked devices).
  • Multicast removes the need to send the same data multiple times, so it reaches various devices, making it a more scalable process compared to unicast.
  • Using multicast communication means only devices that want the data can receive it.
  • The network needs an application that supports multicast traffic to flow to the intended receivers.
  • Stock tickers, smart cars, and digital billboards are examples of multicast in action.