We all know that computer networking is one of the fastest growing fields in Information Technology and it covers a very huge range of technologies, devices and methods.
Connecting individual computers to each other creates networks. The Internet is a series of interconnected networks. Local Area Networks (LAN) or Wide Area Networks (WAN) as well as individual machines are linked together by bridges and hubs. Routers transmit data through networks and determine the best path of transmission. A thorough explanation of networking and all of its aspects follows:
Network
2 or more computers that are connected with each other.
It can share data’s and information to other computers.
Provides connectivity, it can be global or local using the hardware and links.
Examples of network services are:
Electronic mail (E-mail)
Yahoo messenger
E-commerce
Clients and Servers
Are the two entities of network
It designed by the administrator
Servers – provides communication services because it is the central storage for applications and files.
Clients – are the computers that are connected to the server.
Different kinds of Network cables
Twisted pair – this is the industry standard in new installation
There are two types of Twisted-pair
· Shielded Twisted-pair (STP) cable
Ø It combines the techniques of shielding and twisting wires
Ø Usually 150-ohm cable
Ø All four pairs of wires are wrapped in an overall metallic braid or foil.
· Unshielded Twisted-pair (UTP) cable
Ø Is a four pair wire medium that is used in variety of networks.
Ø It relies on the cancellation effect, produce twisted wire pair to limit signal degradation caused by crosstalk and external Electromagnetic Interference (EMI) and Radio Frequency Interference (RFI).
There are two types of UTP Cable
· UTP Category 3 wire – also called as 10BaseT, is use in telephone lines.
· UTP Category 5 wire – also called 10Base2, it is networked standards it is the most commonly use wires.
Coaxial Cable – consists of a center conductor, either stranded or solid, which is surrounded by a layer of insulating material called dielectric.
- All the elements of the coaxial cable encircle the center conductor.
- It is the most widely used medium for transporting high radio frequency signals over a wire, especially cable television signals.
Examples: The antennas leading to most external antennas
Video cable that connect a VCR to a TV.
Fiber – optic – is a networking medium that uses modulated light transmissions. It also used to connect desktop workstations to the network and to link adjacent buildings. It is the most reliable wiring but also the most expensive.
Methods of Connecting
Dial-up Connection ---Standard Phone Line---Ethernet---T1 Connection---Dedicated Line
There are four ways to connect to the Public Internet.
Host access is usually carried out via dial-up telephone lines and modems, combined with internet software on a personal computer, and allows the computer that is accessed to function fully as an internet host.
Network access is similar to host access, but is done via a leased line or an “always-on” link such as Digital Subscriber Line (DSL) or Ether loop. In this case, all the attached computers are made into internet hosts. See also Broadband; Asymmetrical Digital Subscriber Lines.
Terminal access is usually carried out via dial-up telephone lines and modems combined with terminal emulation software on a personal computer; it allows interaction with another computer that is an internet host.
Gateway access is similar to terminal access, but is provided via on-line or similar proprietary services that give the user the ability to exchange e-mail with the Internet.
Service Provider
Company that provides computer access to the Internet, also called Internet service provider (ISP) or access provider. A user subscribes to a service provider, which gives the user an identifying username and password and a phone number. With his or her computer and modem, the user calls, connects to, and logs on to the service provider's computer. The user's computer then lets the service provider's computer take over, acting like a dumb terminal. The user can then utilize any of the tools the service provider's computer provides, which can give access to the World Wide Web (WWW), e-mail, File Transfer Protocol (FTP), Telnet, and other Internet services.
Some service providers charge a monthly or annual fee for Internet access, whereas others provide the service free of charge, and use advertising to generate revenue. The fee charged by the ISP is determined by the type of access offered to the user. In some cases, the user can elect to have a predetermined number of hours on the Internet using a standard free phone telephone number. In others, the user can choose a more expensive, but more capable, broadband connection. The former is an economic way of gaining dial-up access to the Internet; the latter is an always-on service that operates at considerably higher speed than a dial-up connection.
Modem
Ø Device that converts between analogue and digital signals. Digital signals, which are used by computers, are made up of separate units represented by a series of 1s and 0s (bits). Analogue signals vary continuously; an example of an analogue signal is a sound wave. The modem works by, and derives its name from, a process of modulating and demodulating. In the first instance, the digital signal is used to vary an analogue carrier signal. In the second, the variations in the analogue carrier signal are translated into digital signals. Modems are most frequently used to enable computers to communicate with each other across telephone lines. For instance, a modem can be used with a personal computer (PC) to connect to the Internet via an Internet service provider. The service provider’s premises are equipped with banks of modems so that many users can gain access. If each pair of modems transmits data to each other simultaneously, the modems are operating in full duplex mode; if only one modem can transmit at a time, the modems are operating in half-duplex mode.
World Wide Web (WWW)
Ø Library of resources available to computer users through the global Internet. It enables users to view a wide variety of information, including magazine archives, public and college library resources, and current world and business news. World Wide Web (WWW) resources are organized so that users can easily move from one resource to another. The connections to different source computers, or servers, on the network are made automatically without being seen by the user. These connections are made with the use of hypertext and hypermedia.
File Transfer Protocol (FTP)
Ø In computer communications, method of transferring files from one computer to another via the Internet and other networks. The protocol is a set of rules that ensures a file is transmitted properly to the receiving computer. A computer that stores files that can be retrieved using FTP is called an FTP site or FTP server. FTP is part of the Transmission Control Protocol/Internet Protocol (TCP/IP), the system that enables different types of computers and networks on the Internet to communicate.
Telnet
Ø Protocol, or set of procedures, that enables a user of one computer on the Internet to log on remotely to any other computer on the Internet, provided the user has a password for the distant computer or the distant computer provides publicly available files. Telnet is also the name of a computer program that uses these rules to make connections between computers on the Internet. Many computers that provide large electronic databases, like library catalogues, often allow users of Telnet in to search the databases. Many resources that were once available only through Telnet have now become available on the World Wide Web.
Broadband
Ø Communications channel that can support a wide range of frequencies or data rates. A broadband connection can transfer information at a rate of at least 2 megabits per second (mbps). This is almost 40 times faster than a standard narrowband 56 kilobits per second (kbps) modem connection. Some broadband services can even offer 10 mbps connection but, in practice, most transfer information at a rate of around 512 kbps when downloading, and 128 kbps when uploading. There are a number of options for providing broadband. All involve some sort of link between an end user and a switch connected to a wide area network. The simplest option is to install a dedicated link between the two and install suitable transmission equipment at each end. This allows very high-speed operation but is usually expensive. A more affordable approach is to reuse existing telephone lines by adding technology that enhances the rate at which information can be transferred over them.
There are several ways in which this can be achieved:
Ø Integrated Services Digital Network (ISDN), which is widely available and allows connection speeds of up to 128 kbps.
Ø Digital Subscriber Line (DSL), which has recently been introduced and is capable of operating at up to 2 mbps. In its most common format, Asymmetrical Digital Subscriber Line (ADSL), it provides up to 512 kbps downstream and 128 kbps upstream.
Ø Ether Loop, which shares many characteristics of DSL but which follows the format of the ubiquitous local area network technology, Ethernet. Ether loop performance is a little better than DSL.
Ø Cable modems, which are offered by cable providers for Internet access via existing cable television lines. Although capable of connection speed up to 2 mbps, cable modems operate over shared media and are therefore liable to slow down when many users are active.
The real attraction of broadband from a user’s point of view is that it provides true multimedia (for example, voice, data, and video) without the delay that a narrowband connection incurs.
