State the differences between connection less and connection oriented networking system.

Subject Computer Network
NU Year Set: 1.(b) Marks: 5 Year: 2017

Communication can be established in two ways between two or more devices that are connection-oriented and connection-less. Network layers can offer these two different types of services to its predecessor layer for transferring data. Connection-oriented services involve the establishment and termination of the connection while connection-less services don’t require any connection creation and termination processes for transferring data.
Another difference between connection-oriented and connection-less services is connection-oriented communication uses a stream of data and is vulnerable to router failure while connection-less communication uses messages and is robust to router failure.

Definition of Connection-oriented Service

Connection-oriented service is analogous to the telephone system that requires communication entities to establish a connection before sending data. TCP provides Connection-oriented services as does ATM, Frame Relay, and  MPLShardware. It uses handshake process to establish the connection between the sender and receiver.
A handshake process includes some steps which are:
  • Client requests server to set up a connection for transfer of data.
  • Server program notifies its TCP that connection can be accepted.
  • The client transmits an SYN segment to the server.
  • The server sends SYN+ACK to the client.
  • Client transmits 3rd segment i.e. just ACK segment.
  • Then server terminates the connection.


Definition of Connection-less Service

Connection-less service is analogous to the postal system. In which packets of data (usually known as a datagram) is transmitted from source to destination directly. Each packet is treated as an individual entity, which allows communication entities to send data before establishing communication. Each packet carries a destination address to identify the intended recipient.
Packets don’t follow a fixed path that is the reason the packets received at receiver end can be out of order. It uses packet switching for transmission of data.
Most network hardware, the Internet Protocol (IP), and the User Datagram Protocol (UDP) provides connection-less service.
Connection-less Transport services offer only one type of service to its upper layer that is T-UNIT-DATA. It provides a single solitary data unit for all transmission. Each unit contains all of the protocol control information necessary for delivery but does not include provision for sequencing and flow control.


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