| |
A computer
network is an interconnected group of computers. Networks
may be classified by the network layer at which they operate
according to basic reference models considered as standards
in the industry, such as the four-layer Internet Protocol
Suite model. While the seven-layer Open Systems Interconnection
(OSI) reference model is better known in academia, the majority
of networks use the Internet Protocol Suite (IP).
The Open Systems Interconnection Basic Reference Model is
a layered, abstract description for communications and computer
network protocol design. It was developed as part of the Open
Systems Interconnection (OSI) initiative and is sometimes
known as the OSI seven layer model. From top to bottom, the
OSI Model consists of the Application, Presentation, Session,
Transport, Network, Data Link, and Physical layers. A layer
is a collection of related functions that provides services
to the layer above it and receives service from the layer
below it. For example, a layer that provides error-free communications
across a network provides the path needed by applications
above it, while it calls the next lower layer to send and
receive packets that make up the contents of the path.
Types of networks:
Personal Area Network (PAN)
A personal area network (PAN) is a computer network used for
communication among computer devices close to one person.
Local Area Network (LAN)
A network covering a small geographic area, like a home, office,
or building. Current LANs are most likely to be based on Ethernet
technology.
Wide Area Network (WAN)
A WAN is a data communications network that covers a relatively
broad geographic area and that often uses transmission facilities
provided by common carriers, such as telephone companies.
|
|
