SME small business LAN local area network
The term network is used to describe any kind of interconnection between a number of computers (PCs, MACs, UNIX workstations etc), from a pair of PCs to a complex web of interconnected computers around the world. The Internet is perhaps the ultimate network!
Networks are classified according to their geographical span, from local area networks (LANs), which are confined to an office or single building, to wide area networks (WAN), which can interconnect LANs over huge distances. Networks can be connected by cable or by wireless technologies, and are measured in terms of the amount of information they carry (in bits per second) and the bandwidth available.
Data networks have been in operation for several years, allowing users to share resources such as a printer or modem, and to work on the same information or send data to another site. With the increasing convergence of the technologies used for IT and telecoms, networking is becoming an option for voice communications as well, and using a communications server it is already possible to integrate elements of a telephone system and a PC network.
What equipment and technologies are used?
At the heart of the network is the server, which provides collective access to all networked users. Powerful high-speed network servers are on the market, but for a small network a PC can do the same job. PCs and other workstations connected to the server are known as terminals.
Servers are often purpose specific; for example, a print server manages user access to shared printing facilities, a remote access server gives remote users access to the network via a dial-up connection, while a mail server/mail relay provides "post office" services to the network for internal or external e-mail. These functions can be combined in a small network.
Other network components include the hub or switch, which controls communications and access to the equipment connected to the network, and the router, which enables the delivery of data between different networks (where a wide area or remote connection is required).
In terms of security, a firewall provides protection to the network from external users, preventing hacking and unauthorised access. This can be combined with a content checker, which vets information downloaded from the Internet and enables unauthorised or illegal material to be filtered and trapped.
The most commonly used networking technology is Ethernet, which at its simplest only requires a network interface card (NIC) and a length of cable. In the more flexible and robust "star" architecture, each node is connected to a central hub or network switch. A network operating system, such as Windows NT, Novell Netware or UNIX, is used to facilitate and manage networks larger than, say, 5 PCs.
Larger networks are increasingly being connected using asynchronous transfer mode (ATM), which offers high capacity and the "quality of service" provisions required by multimedia applications, but Ethernet remains the LAN technology of choice due to its scalability, affordable hardware, ease of maintenance and implementation, and clear upgrade path as bandwidth requirements increase.
The next technical innovation is likely to be the wireless LAN, or WLAN, which uses radio technology instead of cabling. WLANs are currently capable of delivering speeds of only 1-15Mbps, while cabled networks can easily support up to 100mbps, but on the plus side WLANs can be easily installed and moved within the office area. Still under development, use of a WLAN might be applicable in a small office where speed is not important but where cabling cannot be installed due to physical limitations or other restrictions.
Do I need a network?
If you have more than three PCs in your office it is worth considering the development of a LAN. Having a print server might reduce your operating costs, as users can share one printer. With a mail server you can introduce internal e-mail, which is often more effective than scribbled messages and keeps an official record of communications. And if you are introducing Internet access to your company, a remote access server will enable more than one PC to have access to the Internet with a simple dial-up connection (but do ensure you install an adequate security ‘firewall’).
Reviewed January 2011
last updated : 21/01/2011
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