How to Pick the Right Computer Network
Any computerized office that shares data needs a network. Without it, staffers must carry data-bearing floppy disks from computer to computer--which is not a very efficient operation. But how does an accounting office decide which network configuration to install? What works well in one location may be ineffective in another. This article describes a process for making that selection for small and medium-sized organizations. It examines and compares the three most popular network types: local area networks (LANs), peer-to-peer networks and shared-processor networks. Networks for very large organizations, such as wide area networks (WANs), which are vastly more complicated, are not covered here. FEATURES TO CONSIDER The networking choice that is best for an office depends on a host of variables, which include * Resource constraints. How much money, equipment and human resources can an organization reasonably invest in the networking effort? * Number of user8. Management must consider not only the current number of computer users who will be on the network but also how many users will be added in the years to come. * Peak usage. A network must be able to support peak demands. * Processing complexity. Demand for computer processing time varies depending on the nature of the task. For example, a pool of 10 secretaries who primarily perform word processing puts far less demand on the network than two accountants working on spreadsheet programs. * User locations. The physical distance the network must span influences design choices. * Security. The network must be able to prevent unauthorized access. LOCAL AREA NETWORKS The most popular network configuration is the LAN, in which one or more personal computers (PCs) are the main repositories of all application programs and data files shared by the network users. The central computer is called a file server. While all traffic in the network is managed by the server, all data processing is done locally on each PC. In addition to sharing programs and data stored on the server, users can access each other's data, too. Computers on the network can be connected to a file server in a variety of configurations (see exhibit 1, page 43). A file server must be sufficiently powerful to handle the work load. A 386 computer or higher is recommended because the server needs at least as much random-access memory and speed as a 386 can provide to manage the traffic from the networked PCs. In today's business environments, a 486 computer and the next-generation 586 may be even better choices. LANs are complex and require an expert for setup and support. In addition, a network administrator must be able to maintain all the shared software and assign access rights and passwords to users. Typically, a user terminal (called a node" in LAN jargon) is a PC. However, it can be much less powerful and less expensive (a 286 or even an 8088 computer) than the file server. To communicate over the network, each PC must have a circuit called a network interface card (NIC) installed in it. In addition, special cables must be strung between the file server and each node. These are the major features of LANs: * They can handle a relatively large number of users. The most popular network program, NetWare 386, can link up to 250 computers. * They can accommodate multiple disk operating systems, such as Macintosh, UNIX and MS-DOS. * Their security features are sound. * LANs can communicate with other networks, whether they are similar or not. * Printers can be shared and jobs can be well managed--print queues can be arranged by priority and jobs can be sent to the appropriate printers. These are some of the disadvantages: * LANs need one or more dedicated file servers, whose sole purpose (with some exceptions) is to run the network. …