Unicast Broadcast and Multicast in Computer Networks

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We will try to understand Unicast Broadcast and Multicast in Computer Networks in this class.

We have already discussed the concept of classful addressing in our previous classes.

Unicast Broadcast and Multicast in Computer Networks

Transmitting the data in the form of packets over the internet is called casting.

There are three types of casting in computer networks

1. Unicast
2. Broadcast

2.1 Limited Broadcast Address

2.2 Directed Broadcast address

     3. Multicast

Unicast 

This type of information transfer is proper when a single sender and single recipient are involved.

The image below is the visualization of unicast.

Here computer A in Network 1 wants to transmit the message to computer B in network 2.

Network 1 is a Class A address, and Network 2 is a Class C address. 

The Network ID of Network 1 is 24.0.0.0, and the Network ID of Network 2 is 194.2.8.0.

The first IP address is used as the Network ID among all the IP addresses.

In our case, the IP addresses 24.0.0.0 and 194.2.8.0 are used as the network ids for networks 1 and 2.

Broadcast

In Broadcast transmission, the data is transmitted from one or more senders to all the receivers within the same network or in other networks. 

Broadcast is made in two different ways.

1. Limited Broadcast
2. Directed Broadcast

In Limited Broadcast, the data is transmitted to all hosts residing in the same network from a single source host.

The image below is the visualization of limited broadcast.

Here the message has to be transmitted from A to all the computers in the same network. 

For this kind of broadcast to happen, the IP address 255.255.255.255 is used.

255.255.255.255 is a Class E Reserved address.

Directed Broadcast transmits data from one source host to all the other hosts in some other network.

The image below is the visualization of the directed broadcast.

Here, the message must be transmitted from computer A in Network 1 to all computers in network B.

For this kind of broadcast, the last IP 194.2.8.255 of network B is used as the destination address.

The directed broadcast address and the network id should not be assigned to the hosts.

Therefore the number of hosts in a network should be 2^(Number of suffix bits) – 2.

Multicast

When the data is transmitted from a single source host to a specific group of hosts interested in receiving the data, it is known as multicast transmission.

Class D addresses are multicast addresses.