Definition of a Network
A network is a group of computers that are all connected together in order to share other connected resources. These resources include files, printers, databases and, of course, an internet connection. Whether a network is a wired one or wireless, they will always be made up of a certain amount of network media such as;
- cables (in wired networks)
- network adapter hardware (to translate the data between the computer and the network media),
- an operating system (to enable the computer to recognise the network)
- a network protocol (to control the network communication)
All of the above are required, and work together, to enable a fully functioning computer network. Additionally, any computer or device that will communicate with a network also require a Network Interface Card (NIC). In present day, most devices are manufactured with a built in NIC. However, older devices may require an adapter card that can be inserted into an expansion card port or slot.
Network Models
There a two primary network models and these act as design specifications for how computers, devices and other nodes on a network can interact.
Client-Server
- A client/server network is a network in which the functionality of computers is divided into two distinct roles.
- Server computers; which provide services and network control operations
- client computers; which use the services provided by the server computers.
- Under normal circumstances there is at least one server which provides a central authentication service.
- The server computers will also provide access to shared files, printers, hardware and applications.
- In client-server networks, administrative functions, management services and processing power can all be concentrated where they are required most while client machines can still perform many of the basic end-user functions on their own.
- In some cases, client-server network types can be known as domains. Microsoft Windows Servers are one such example.
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| Client computers connecting to a server computer (e.g. Google) over the internet |
Peer-to-peer
- A peer-to-peer network is a network in which control of resource sharing, processing and network control are all completely decentralised.
- All devices on the network are equal in the terms of providing and using resources and users have to be authenticated at each individual workstation.
- Peer-to-peer networks are easy and cheap to implement but are only practical in very small organisations due to the lack of central administration and data storage.
- Each user account MUST be duplicated on every workstation that a user is going to access resources.
- Such distribution of user information makes maintaining peer-to-peer networks difficult, especially as the network increases in size.
- Peer-to-peer networks should not exceed any more than ten computers.
- Windows ‘workgroups’ are an example of a peer-to-peer network.
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| An example of an unstructured Peer-to-Peer network. |
Network Types
Additionally to the two network models described above, there are different ways to set networks up in order to define how they behave. Below are the descriptions of the different network types.
Local Area Networks
A Local Area Network (LAN) is a self-contained network that spans a small area, such as a single floor of a building, the building itself, or even a single room. In a LAN, all parts of the network are directly connected with cables or short-range wireless technology.
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| Local Area Network Concept |
Wide Area Networks
A Wide Area Network (WAN) is a network that encompasses multiple geographic locations. In normal circumstances, WANs connect multiple LANs using long-range transmission media and facilitate the communication of user and computers in multiple geographic locations. WANs can be private, such as those used by multinational corporations or they can be public, such as the internet
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| LAN to WAN connection concept |
Personal Area Network
A Personal Area Network (PAN) connects two or three devices together for use by a single person, normally using a router with cabling. These types of network are most often seen in the home or in small offices.
A Wireless Personal Area Network (WPAN) is a network that connects wireless personal devices, although not through a Wireless Access Point (WAP). Such networks ordinarily utilise Infrared or Bluetooth technologies.
Metropolitan Area Network
A Metropolitan Area Network (MAN) covers an area equivalent to a town or city and, in many cases, connects multiple LANs. Although the technologies involved differ, the principles are not that removed from those of a WAN.
Virtual Private Network
A Virtual Private Network (VPN) is a private communications network that’s transmitted across a public and typically insecure network connection, such as the internet. With a VPN, it’s possible for companies to be able to extend a virtual segment of their LAN to employess working at remote locations, such as at home or ‘in the field’, by transmitting data securely across the internet.
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| An Internet based VPN |
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