NETWORKING Mahesh & Naveen. A NETWORK The connection of two or more computers which may or may not be situated in a particular geographic location.

NETWORKING

Mahesh & Naveen

A NETWORK

The connection of two or more computers which may or may not be situated in a particular geographic location.

Computers linked together to enhance individual and group productivity

Use Of Networks

Networks facilitate:

Sharing of data and resources (e.g. Files, databases, application software, scanners, printers, discs, etc.)

communication (e.g. E-mails, Remote computing GRID computing.

Types Of Networks

PAN (Personal Area Network) LAN (Local Area Network) CAN (Campus Area Network) MAN (Metropolitan Area Network) WAN (Wide Area Network) Internetwork

PAN (Personal Area Network)

It is a computer network used for communication among computer devices close to one person. Some examples of devices that are used in a PAN are printers, fax machines, telephones, PDAs and scanners. The reach of a PAN is typically about 20-30 feet (approximately 6-9 meters), but this is expected to increase with technology improvements.

PANs may be wired with computer buses such as USB and FireWire. A wireless personal area network (WPAN) can also be made possible with network technologies such as IrDA and Bluetooth.

PAN

LAN (Local Area Network)

This is a network covering a small geographic area, like a home, office, or building most likely based on Ethernet technology.

The defining characteristics of LANs, in contrast to WANs (wide area networks), include their higher data transfer rates, smaller geographic range, and lack of a need for leased telecommunication lines.

LAN (Local Area Network)

Example: A library may have a wired or wireless LAN for users to interconnect local devices and to connect to the internet. The staff computers (bright green in the figure) can get to the colour printer, checkout records, and the academic network and the Internet. All user computers can get to the Internet and the card catalogue. Each workgroup can get to its local printer.

Typical library network, in a branching tree topology and controlled access to resources

Note that the printers are not accessible from outside their workgroup.

LAN

CAN (Campus Area Network)

This is a network that connects two or more LANs but that is limited to a specific and contiguous geographical area such as a college campus, industrial complex, office building, or a military base. A CAN may be considered a type of MAN (metropolitan area network), but is generally limited to a smaller area than a typical MAN. This term is most often used to discuss the implementation of networks for a contiguous area.

CAN

MAN (Metropolitan Area Network)

A MAN is optimized for a larger geographical area than a LAN, ranging from several blocks of buildings to entire cities.

A MAN might be owned and operated by a single organization, but it usually will be used by many individuals and organizations.

A MAN is a large computer network that spans a metropolitan area. Its geographic scope falls between a WAN and LAN. MANs connect LANs to wider area networks like the Internet.

WAN (Wide Area Network)

A WAN is a network that covers a relatively broad geographic area (e.g. one country to another country) and that often uses transmission facilities provided by carriers, such as telephone companies.

WANs are used to connect LANs and other smaller networks together.

WANs are often built using leased lines. At each end of the leased line, a router connects to the LAN on one side and a hub within the WAN on the other. Leased lines can be very expensive so instead of using them, WANs can also be built using cheaper circuit switching or packet switching methods.

WAN

A diagrammatic presentation of a Wide Area Network (WAN)

Internetwork

Two or more networks or network segments connected using devices such as a router. Any interconnection among or between public, private, commercial, industrial, or governmental networks may also be defined as an internetwork.

In modern practice, the interconnected networks use the Internet Protocol. There are at least three variants of internetwork, depending on who administers and who participates in them:

• Intranet • Extranet • Internet

Intranet, Extranet & Internet

• Intranet: An intranet is a set of networks, using the Internet Protocol and IP-based tools such as web browsers and file transfer applications, that is under the control of a single administrative entity.

• Extranet: An extranet can be understood as an intranet mapped onto the public Internet or some other transmission system not accessible to the general public, but managed by more than one company's administrator(s).

• Internet: The Internet is a global system of interconnected computer networks that interchange data by packet switching using the standardized Internet Protocol Suite (TCP/IP). It is a "network of networks" that consists of millions of private and public, academic, business, and government networks of local to global scope that are linked by copper wires, fibre-optic cables, wireless connections, and other technologies.The Internet carries various information resources and services, such as electronic mail, online chat, file transfer and file sharing, online gaming, and the inter-linked hypertext documents and other resources of the World Wide Web (WWW).

Internet

THE INTERNET

Components Of A Network

Network Interface Cards: A network card, network adapter or NIC (network interface card) is a piece of computer hardware designed to allow computers to communicate over a computer network. It allows users to connect to each other either by using cables or wirelessly.

Repeaters: It is an electronic device that receives a signal and retransmits it at a higher power level, or to the other side of an obstruction, so that the signal can cover longer distances without degradation. In most twisted pair ethernet configurations, repeaters are required for cable runs longer than 100 meters away from the computer.

Hubs: A hub contains multiple ports. When a packet arrives at one port, it is copied to all the ports of the hub for transmission.

Bridges: A network bridge connects multiple network segments. Once the bridge associates a port and an address, it will send traffic for that address only to that port. Bridges do send broadcasts to all ports except the one on which the broadcast was received.

Switches: Switch is a marketing term that encompasses routers and bridges, as well as devices that may distribute traffic on load or by application content (e.g., a Web URL identifier).

Routers: They are networking devices that forward data packets between networks using headers and forwarding tables to determine the best path to forward the packets. Routers also provide interconnectivity between like and unlike media. This is accomplished by examining the Header of a data packet, and making a decision on the next hop to which it should be sent.

Components of a network

A network bridge

A Hub A wireless repeater A router

A network switch

Network Media

Networking media can be defined simply as the means by which signals (data) are sent from one computer to another (either by cable or wireless means). They can be:

• Copper cables• Optical fibers• Air (Wireless media)

(Insulated copper wires)

Twisted-pair cable

Protective sheath

Wire mesh shield

Copper wire

InsulationCoax cable

Fiber optic cable

Protective sheath

Glass core

Glass cladding

Client And Servers

A client is an application or system that accesses a remote service on another computer system, known as a server, by way of a network. The term was first applied to devices that were not capable of running their own stand-alone programs, but could interact with remote computers via a network. These dumb terminals were clients of the time-sharing mainframe computer.

A server is a computer dedicated to providing one or more services over a computer network, typically through a request-response routine. These services are furnished by specialized server applications, which are designed to handle multiple concurrent requests. Examples of server applications include mail servers, file servers, web servers, and proxy servers.