Computer Networking

COMPUTER NETWORKING

Computer networking is the engineering discipline concerned with communication between computer systems. Such communicating computer systems constitute a computer network and these networks generally involve at least two devices capable of being networked with at least one usually being a computer. The devices can be separated by a few meters (e.g. via Bluetooth) or nearly unlimited distances (e.g. via the Internet). Computer networking is sometimes considered a sub-discipline of telecommunications, and sometimes of computer science, information technology and computer engineering. Computer networks rely heavily upon the theoretical and practical application of these scientific and engineering discliplines.
A computer network is any set of computers or devices connected to each other. Examples of networks are the Internet, a wide area network that is the largest to ever exist, or a small home local area network (LAN) with two computers connected with standard networking cables connecting to a network interface card in each computer.

THE ISO MODEL FOR COMMUNICATION

ISO (the International Organization for Standardization) has developeda standard model for communications, called the OSI (Open Systems Interface) Model
Model = it means that it's only theory! In fact the OSI model is not yet fully implemented in real networks.
Open System: It can communicate with any other system that follows the specified standards, formats, and semantics.
Protocols give rules that specify how the communication parties may communicate.
Supports two general types of protocols. Both are common.
Connection-Oriented:
Sender and receiver first establish a connection, possibly negotiate on a protocol. (Virtual circuit)
Transmit the stream of data.
Release the connection when done.
E.g. Telephone connection.
Connectionless
No advance setup is needed.
Transmit the message (data grams) when sender is ready.
E.g. surface mail