February 14, 2020
Amitraj
Switching
The process of moving the data packets towards their destination by forwarding them from one port to the other port is called as switching.
Switching Techniques
There are various switching techniques:-
1. Circuit Switching
2. Packet Switching
3. Message Switching
1. Circuit Switching -
Circuit Switching establishes a physical path between the sender and receiver of the message before a message is delivered. When a connection is established between a sender and a receiver, the entire message travels through the established path from sender to the receiver. Once the message is delivered to the receiver, the source informs the network about the completion of transmission and all the switches released. Then the link and other connecting devices are used to set up another connection.
-> To make the process happen the three functions are executed.
Circuit establishment: An end-to-end connection is established between the nodes before transmission of the data.
Data transfer: The data is commonly transferred in full-duplex mode from sender to receiver.
Circuit disconnect: When the data transfer is completed the connection is terminated and the engaged resources are deallocated.
Circuit switching is always implemented at the Physical Layer. Circuit switching can be explained with an example of a telephone conversation. In a telephone conversation, once a connection is established, between a caller and the receiver, it remains connected, till the whole conversation is finished and both the caller and receiver hang up their phone.
The Circuit switching is not appropriate for data transmission because data is transmitted in spurts (stream) and the line remains idle for most of the times and hence, the bandwidth is wasted. Circuit Switching can be implemented using two technologies either Space Division Switching or Time Division Switching.
Total Time-
where-
-> Transmission delay = Message size / Bandwidth
-> Propagation delay = (Number of hops on way x Distance between 2 hops) / Propagation speed
Advantages-
1. There is no waiting time at any switch and the data is transmitted without any delay.
2. There is no header overhead.
3. Data always reaches the other end in order.
4. No re ordering is required.
Disadvantages-
1. The time required for establishing the circuit between the two ends is too long.
2. Dedicated channels require more bandwidth.
3. The channel is blocked for two ends only.
4. It is more expensive than other switching techniques.
Important Note-
The process of moving the data packets towards their destination by forwarding them from one port to the other port is called as switching.
Switching Techniques
There are various switching techniques:-
1. Circuit Switching
2. Packet Switching
3. Message Switching
1. Circuit Switching -
Circuit Switching establishes a physical path between the sender and receiver of the message before a message is delivered. When a connection is established between a sender and a receiver, the entire message travels through the established path from sender to the receiver. Once the message is delivered to the receiver, the source informs the network about the completion of transmission and all the switches released. Then the link and other connecting devices are used to set up another connection.
-> To make the process happen the three functions are executed.
Circuit establishment: An end-to-end connection is established between the nodes before transmission of the data.
Data transfer: The data is commonly transferred in full-duplex mode from sender to receiver.
Circuit disconnect: When the data transfer is completed the connection is terminated and the engaged resources are deallocated.
Circuit switching is always implemented at the Physical Layer. Circuit switching can be explained with an example of a telephone conversation. In a telephone conversation, once a connection is established, between a caller and the receiver, it remains connected, till the whole conversation is finished and both the caller and receiver hang up their phone.
The Circuit switching is not appropriate for data transmission because data is transmitted in spurts (stream) and the line remains idle for most of the times and hence, the bandwidth is wasted. Circuit Switching can be implemented using two technologies either Space Division Switching or Time Division Switching.
Total Time-
Total time taken to transmit a message in circuit switched network
= Connection set up time + Transmission delay + Propagation delay + Tear down time
= Connection set up time + Transmission delay + Propagation delay + Tear down time
where-
-> Transmission delay = Message size / Bandwidth
-> Propagation delay = (Number of hops on way x Distance between 2 hops) / Propagation speed
Advantages-
1. There is no waiting time at any switch and the data is transmitted without any delay.
2. There is no header overhead.
3. Data always reaches the other end in order.
4. No re ordering is required.
Disadvantages-
1. The time required for establishing the circuit between the two ends is too long.
2. Dedicated channels require more bandwidth.
3. The channel is blocked for two ends only.
4. It is more expensive than other switching techniques.
Important Note-
-> Circuit switching is now outdated.
-> Circuit switching is implemented at physical layer.
Also Read - Packet Switching
-> Circuit switching is implemented at physical layer.
Also Read - Packet Switching
