Connection-oriented

Connectionless

Definition

In this communication, it requires the establishment of a connection between communicating nodes before it will transmit data.

This type of communication serves a request without requiring a verified session and without guaranteeing delivery of data.

Comparison

As the device gets data, it does initiating, negotiating, managing and at last terminating processes.

As soon as it gets data to transmit, it just sends them.

TCP, X.25, Frame relay, GPRS, ATM

UDP, IP, ICMP

IP can run over a connection-oriented protocol like ATM

Telnet (which requires a connection) running over IP (which is connectionless)

Contrast

Reliable

Not reliable

High overhead

Low data overhead

Good for ‘unicast’

Good for ‘broadcast’ and ‘multicast’