Why network?

A rationale for using networks

Wherever more than a few computers are needed, a network is worth considering. There are many significant benefits to networking PCs, mainly related to convenience, communication and cost.

Device sharing

If you had six stand-alone computers that needed to print, you would need six printers. If you had one Internet connection only one computer could access the Internet.

Networking saves money by sharing expensive devices between computers. On a network, you can let any number of computers share a single resource such as an Internet connection, a printer or a download cache.

Sharing and licensing software

If you store a program on a networked file server you don't need to install it on every workstation. This saves a lot of installation time.

When licensing software for a network, pay close attention to the conditions of its use. Some licences let you install software on any number of computers, so long as the number of people using the software at a given time does not exceed the number of licences purchased. Some network operators run special software that ensures that only the legal number of users can run software concurrently. Other software licensing requires a licence for each computer onto which the software is installed.

There are usually special cheaper rates for licensing software for network use.

It is wise to obey licensing conditions: organisations can be seriously embarrassed and fined for using software illegally.

Sharing information

The main attraction of networking is the sharing of an Internet connection so it can be used by several local computers to access websites or files.

With networking, you can set up an Intranet - a local version of the Internet - so information can be shared between all network users without the fear that outsiders can see it.

Many larger organisations have networked calendars for their staff. People can check their colleagues' appointments online so they can book meetings. It may sound boring, but it's better than running to a colleague's office every fifteen minutes on an urgent matter only to find they are still in a meeting, or on the phone.

Communications - messaging, email, ecommerce, chat, videoconferencing

Communication is the lifeblood of any organisation. No organisation can ever be too efficient with communication, and networks are great for communication. This is the focus of the next section of this chapter.

Functions of network services

What services can a network offer its users? Everything short of a handshake and a back rub. Here are some of them:

Email

A network enables email - electronic mail. Email can be sent and received at any time or place, unlike telephone calls and public-address announcements which have to be handled immediately and can often interrupt more important business.

Email gives the sender and recipient the luxury of thinking about what they are saying, and editing their words before they are sent. Since email is stored, no notes need be taken during phone calls, and old correspondence can be searched and printed. Team workers can easily share documents by attaching them to emails and sending them instantly anywhere in the world.

Did you know.

For most people, email is transferred using the Post Office Protocol (usually POP3).

The POP server is the incoming mail server. SMTP (Simple Mail Transfer Protocol) is the outgoing mail server. Just remember that you can "POP in" and visit someone: POP is incoming.

The drawback of email is spam: unsolicited email. Spam is a growing problem as the mass of unwanted mail clogs up mail servers and users' email boxes, and wastes workers' time. Some users respond by using strict, automatic filtering of incoming email. The danger is that valid emails can be treated as spam and deleted.

Did you know.

E-mail was invented by Ray Tomlinson in 1972. He picked the @ symbol from the available symbols on his  teletype to link the username and address.

FTP

FTP (File Transport Protocol), first developed in 1973, is a method of sending computer files across the Internet. When downloading a program or a new driver for your printer, you could well be using FTP.

WWW

The World Wide Web (WWW) protocol for information distribution was invented in 1989 by Tim Berners-Lee to share formatted pages of hypertext information across the Internet. Using the HTTP (Hypertext Transfer Protocol) and HTML (Hypertext Markup Language), documents appear on the Internet in a format that any computer could understand and display. The World Wide Web appeared in 1991.

HTTP remains the standard for web pages, and most web browsers display the same web page in much the same way, regardless of the type of computer being used. The first web browser, Mosaic, appeared in 1993 and led to today's main web browsers: Netscape, Internet Explorer and Opera.

Did you know.

The World Wide Web was named by Tim Berners-Lee, who invented HTTP and said: "Alternative names I considered were Mine Of Information ("Moi", c'est un peu egoiste) and The Information Mine ("Tim", even more egocentric!), and Information Mesh.

DHCP (Dynamic Host Configuration Protocol)

DHCP is a service provided by Internet-enabled file servers to allocate valuable Internet Protocol (IP) addresses to computers in their network on request. Most large LANs have more workstations than they do IP addresses, but not all workstations need the Internet at the same time. Organisations can save money by allocating IP addresses only when required.

Telnet

The telnet protocol, developed in 1972, lets authorised users log on to and operate a remote computer as if they were at its keyboard.

File sharing

Networks and the Internet let you easily distribute your program code, report or picture to people in your department, or anyone in the world. Small-time programmers, struggling musicians and keen artists can share their work with anyone on Earth. More than one unknown programmer or artist has become "big" by sharing files through services like Napster or Tucows.

On an intranet, you can distribute files needed by all employees, such as policies, document templates and company news.

Virtual private networks

Operating a WAN, until recently, has meant the leasing expensive ISDN lines. As the Internet grew, businesses realised they could use it as a channel between their LANs to create a cheap WAN.

A Virtual Private Network (VPN) is a private network that uses the Internet to connect remote sites or users. VPN uses "virtual" connections routed through the Internet from the company's private network to the remote site or employee. It is a cheap and effective way of using existing technology to get you from "A" to "B" without anyone else seeing what is being transmitted.

Online chat

While online chat (such as ICQ and AOL Instant Messenger) may be a valuable way for teenagers to discuss Britney Spear's latest song, it can also be a valuable alternative to the telephone for organisations.

While online chat is still synchronous (happening in real time) like the telephone, it offers the advantages of being able to transmit files and save the discussion for later reference. It is also cheaper than international telephone calls, and eliminates noisy lines and foreign accents that may be hard to understand.

Remote control

Technicians and helpdesk staff can help workers with computer problems quickly and easily by using remote control software to demonstrate how an operation is performed, or fix problems by simply taking over the remote workstation as if they were at the keyboard.

The technician or helpdesk operator can remotely see the person's screen, control their keyboard and mouse and talk to them by online chat. This allows them to efficiently help colleagues anywhere in the building or anywhere in the world.

With such services, large organisations could have a single expert helpdesk in one location and offer hands-on assistance to employees across the LAN or WAN. You'd neither know or care whether your computer problem was being solved by a person in Manchester or Melbourne.

Videoconferencing

In the bad old days, meetings often required long, expensive and tiring travel. With networking, cheap cameras and microphones, distant branches of an organisation can communicate face-to-face with videoconferencing. It is immediate, cheap and convenient. It allows immediate communication between neighbouring offices or distant countries. There have been several cases of law courts using videoconferencing to hear from witnesses who could never have attended personally because of time, distance, cost or health constraints.

Collaborative work

Networked documents let colleagues work on the same project at the same time. Most documents can only be opened by one user at a time: once a user opens a document, the network puts a file lock on the document so no other user can open it. Databases, however, can usually be used by many people at once.

Professional software such as the web page editor Dreamweaver lets several people work simultaneously on the same website (but not the same page) to improve workplace efficiency.

Types of resources found on a typical LAN

Networks offer many resources and services for all users.

Shared equipment

High quality printers and photocopiers are often designed to connect directly to a network and all authorised users can share the equipment. A job sent by a user is put into a queue to be handled by the equipment in its turn.

Internet

An organisation can have one connection to the Internet that is shared by all network users. Since it is common for several users to download the same material from the Internet, a common service on networks is a proxy server that caches (stores) recent downloads. If another user requests the same download, the proxy server provides the file from its storage rather than downloading it again.

Centralised file saving

Workers are often moving from place to place at work. If they saved their documents to a hard disk on one workstation, they would not be able to load them at another workstation. By saving files to their home directories on the file server, workers can load their documents on any networked computer.

Centralised virus scanning

Most file servers run virus scanners constantly to detect and take care of viruses introduced by any user on any computer.

Intranet

An Intranet is like a local internet. It is not available outside the organisation's network, so it can be used to publish "in house" material such as meeting schedules, sensitive documents about projects, and internal "housekeeping" issues. The intranet files are normal web pages and are read by standard web browsers. The main difference is that the files are stored on a local file server rather than a public web server.

Voice over IP, media streaming

Rather than have one set of cables around a building for the network, another set for the phone system, and another set carrying video, many organisations are now combining their phone and audio-visual systems into their network so phone calls and videos are digitised and transmitted like files.

More on Voice Over IP (VoIP)

Software deployment

Instead of visiting hundreds of workstations in person, network technicians can install or upgrade software from a central location across the network by "broadcasting" the changes. It saves time and money and, since the task is done just once, fewer errors are likely to be made.

Centralised backups

High-capacity tape devices in the file server back up all users' work, usually every night. In case of system failure (or worker failure), lost work can be recovered quickly and easily.

CD towers / CD image sharing

A CD tower is a specialised server that contains many CD-ROM drives that it can use to deliver CD-ROM data across the network as if the user had a CD-ROM drive in their own computer; but it is cheaper to use a CD tower than it is to buy a CD-ROM drive for every workstation. A 'virtual' CD server can be used to copy entire CDs to a hard disk and send the data when requested. The number of different CDs that can be served is only restricted by the size of the server's hard disk.