Casting And Its Types

Casting is a method of transferring a packet to various hosts simultaneously by using an IP address. 

Types of Casting

There are three types of casting

1. Unicast

• Transmitting a packet from one source node to one destination node is called as unicast.
• We can say, it is a one to one transmission.

Example

Consider a Node/Host “A” having IP Address 11.2.2.31 in one network is sending data to Node/Host “B” having IP Address 21.11.41.21 in another network.

Then,

• Source IP Address of Host A = 11.2.2.31
• Destination IP Address of Host B = 21.11.41.21.

2. Broadcast

• In Broadcasting, Packet is send to all residing host in the same or different network, depending on its types.
• It is a one to all transmission.

Broadcasting is of two types

1. Limited Broadcast
2. Direct Broadcast

A. Limited Broadcast

According to Limited Broadcasting, Packet is send to all residing host in the same network

• If a Host need to send a broadcast message with in the same network then All 32 bits of IP address are set to 1. As
• Limited Broadcast Address for any network = 11111111.11111111.11111111.11111111 = 255.255.255.255
• This IP address cannot pass through router to go for another network.

 Example

Consider a Node/Host “A” having IP Address 11.2.2.31 is sending data to all other hosts residing in the same network.

Then,

• Source IP Address = IP Address of host A = 11.2.2.31
• Destination IP Address = 255.255.255.255

B. Direct Broadcast

According to direct Broadcasting, Packet is send to all residing host in the other network

• If a Host in a network wants to send a broadcast message to other network then all hosts bits of IP address are set to 1.
• This IP address cannot pass through router to go for another network.

Example

Host “A” in one Network having IP Address 11.11.121.13 sending data to all other hosts residing in the network having IP Address 21.0.0.0

Then,

• Source IP Address of host A = 11.11.121.13
• Destination Address = 21.255.255.255

3. Multicast

• Transmitting data packet from one source Node to a particular group of Nodes is known as Multicast.
• It is also an example of one to many transmission.

Examples

• Sending a message to group of people on whatsapp.
• Video conference to a particular group of people

Note: To identify the group in multicast, IGMP (Internet Group Management Protocol) is used.

Summary of Transmission Types