GATE Computer Science Engineering(CSE) 2027 Test: Switching Techniques

Application layer is the topmost layer in the OSI model. Network virtual terminal, mail service, file transfer, access and management are all services of the application layer. It uses protocols like HTTP, FTP, and DNS etc. to provide these services.

Circuit switching is connection oriented and is always implemented in the physical layer. Once a path is set, all transmission occurs through the same path. It is used since the early times in telephonic systems.

Packet switching and Circuit switching are two different types of switching methods used to connect the multiple communicating devices with one another. Packet switching is used in conventional LAN systems and circuit switching is used in telephonic systems.

The packet switch will not transmit the first bit to outbound link until it receives the entire packet. If the entire packet is not received and the time-out period expires, the packet switch will inform the sender to resend the part of packet or the entire packet based on the algorithm being used.

In packet switching, the bits are received in out of order and need to be assembled at the receiver end, whereas in the case of Circuit switching, all the bits are received in order. All transmissions may not occur through the same path in case of packet switching.

In circuit switching, a physical path between the sender and receiver is established. This path is maintained until the connection is needed. Circuit switching is implemented in the Physical layer and is used in telephonic systems.

The equation to find the end to end delay when no. of bits, transmission rate and no. of routers is given by (N*L)/R. The total end to end delay, that is, nodal delay is the sum of all, the processing delay, queuing delay, transmission delay and propagation delay.

Circuit switching is connection oriented switching technique, whereas in the case of packet switching, it is connectionless. Circuit switching is implemented in the Physical layer, whereas packet switching is implemented in the Network layer. Internet too is based on the concept of circuit switching.

Circuit switching is a switching technique in which a point-to-point physical connection is made between two or more devices.
For example: Telephone system, in which sender and receiver are connected by physical connection, such as wire.

In packet switching, the message is divided into small parts. These small parts of the message are called packets, and each packet has its own source and destination address. Each packet is transmitted forward in the network only on the basis of these addresses.