2.6 Geographical Area
Computer networks are classified according to their geographical area (Balasubramanian et al, 2006). They are:
Local area network (LAN): This is a network that connects computers and devices in a limited geographical area such as home, school, computer laboratory, office building, or closely positioned group of buildings. Each computer or device on the network is a node. Current wired LANs are most likely to be based on Ethernet technology, although new standards like ITU-TG.hn also provide a way to create a wired LAN using existing home wires (coaxial cables, phone lines and power lines).
Technically, this is the simplest type of computer network, they are widely used to connect personal computers and work stations in company offices and factories and to share both hardware and software resources. Examples of the resources shared are printers, scanners, laminators.
The defining characteristics of LANs, in contrast to WANs (Wide Area Networks), include their higher data transfer rates, smaller geographic range, and no need for leased telecommunication lines. Current Ethernet or other IEEE 802.3 LAN technologies operate at speeds up to 10gigabit/s. This is the data transfer rate. IEEE has projects investigating the standardization of 40 and 100gigabit/s. LANs can be connected to Wide area network by using routers.
Wide Area Network (WAN): WAN is a computer network that spans a large geographical area. It uses dedicated or switched connections to link computers in geographically remote locations wide area networks are implemented to connect large number of WANs and MANs. Due to this reason, it is possible to see a large number of heterogeneous components in a wide area network. Different communication media are used and the network spreads across several national boundaries. Computers connected to a WAN are often connected to a public network. They can also be connected through leased lines or satellite links. WAN is mostly used by government or large concerns because of the huge investment made to implement them.
Computer networks also enable resource sharing, an important consideration in all budget-conscious organizations. Rather than buying one printer for every employee and replacing them when they wear out, an organization with a network can buy a single printer, connect it to the network, and configure it in such a way that every computer user in the organization can print to it. The initial cost of a networked printer is usually more than the cost of a single desktop printer, but when considering costs on a per-user basis, the average cost of the networked printer is often much less than the cost of buying a printer for every employee. While some networked devices such as printers, scanners, and fax machines have predetermined, specialized functions, you can also network and share generic, unspecialized computing power in the form of servers.
Servers are large, powerful computers that can handle resource-intensive tasks more efficiently than desktop computers. As with the networked printer, the initial outlay for a server is more than that for a desktop computer, but across the organization, it's often cheaper to run the server-based version of a program since individual users won't need expensive, high-performance desktop and laptop computers. Servers can also deploy software to other networked machines at a lower cost
2.7 Network Monitoring System
Network monitoring system monitors an internal network for problem(s). It can find and help resolve snail placed webpage downloads, lost in space e-mail, questionable user activity and file delivery caused by overhead, crashed servers delay network connections or other devices.
Network monitoring systems are much different from intrusion detection systems, it let one knows how well the network is running the course of ordinary operation; its focus isn’t on security. Network monitoring can be achieved using various software or a combination of plugs and play hardware and software appliances solutions.
Virtually any kind of network can be monitored. It doesn’t matter whether it is wired or wireless, a corporate LAN, VPN or service providers WAN. One can monitor devices on different operating systems with multitude of functions, ranging from blackberries, cell phones, to servers, routers and switches. These systems can help identifies specific activities and performance matrices, producing results that enables business to address sundry needs, including meeting compliances requirement, stomping out internal security threats and providing operational visibility.
According to Winggin and Christopher (1998), a network monitoring systems comprises the following:
➢ A computer including processing means for executing a multi-tasking operating systems which is capable of running a plurality of user applications each of which being associated with an active or inactive window, with a user application provided by at least one of a service and a server.
➢ A graphical user interface on the system running monitoring software.
➢ The network monitoring system should have a user prompting means for first time in the priority scheduling.
➢ A closing menu user application is associated to inactive window for a period greater than the predetermined scheduled time.
➢ The network monitoring systems should have identification (ID) means for generating an access request for user application and a termination request when an ID is invalid which is subject to license restriction.
