Explain the connection oriented and connectionless services.

Connection Oriented Services

Connection-oriented communication includes the steps of setting up a call from one computer to another, transmitting/receiving data, and then releasing the call, just like a voice phone call. Connection-oriented services must first establish a connection between the two end-points (sending/receiving) before passing any data traffic between them. Connection-oriented service involves three phases:

Connection Establishment
Data Transfer
ConnectionTtermination

Connection oriented services are often but not always reliable network services, that provide acknowledgment after successful delivery, and automatic repeat request functions in case of missing data or detected bit-errors. ATM, Frame Relay and MPLS are examples of a connection-oriented, unreliable protocol.

Representation Of Connection Oriented and Connectionless Services

Connectionless Services
Connectionless services can send data without requiring an established connection. A packet transmitted in a connectionless mode is frequently called a datagram. Connection-oriented services provide some level of delivery guarantee, whereas connectionless services do not. An example of a connectionless service is any IP service, such as the Internet. No established connection is made between a web browsing user and the home page being viewed. Connectionless protocols are usually described as stateless protocols because the end points have no protocol-defined way to remember where they are in a "conversation" of message exchanges. The connectionless communications has the advantage over connection oriented communications in that it has low overhead. It also allows for multicast and broadcast operations, which may save even more network resources when the same data needs to be transmitted to several recipients.

Internet Protocol (IP) and User Datagram Protocol (UDP) are examples of connectionless protocols.