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PC Network
Networking is all about sharing-data, software, and peripherals such as printers, modems, fax machines, tape drives, hard disks and other data storage equipment-among a group of computers. A network can be as small as two computers linked by cable or so large that it connects hundreds of computers and peripherals in various configurations.
This article provides basic information on networking including network cabling, switched networking and fast Ethernet networking.
A network saves time and money, by enabling employees to communicate and share information. It cuts costs further by eliminating the need for extra printers, modems and file storage; on a network, all of this technology can be shared. Even an outside line for Internet access can be shared over the network. Network layout (also called "topology") refers to the physical design of a network. There are three basic layouts: star, bus or ring. Star and bus, the most common layouts for local area networks (LANs), are described below.
Local Area Network (LAN)- A network in a localized (not remote) location that allows users to share information, equipment and resources.
Star Layout
As its name implies, this layout resembles a star. At the center of each star is a hub or switch that connects directly to each node via a thin, flexible cable (such as 10/100BASE-T cable). One end of the cable plugs into the connector on the network adapter card; the other is connected directly to the hub or switch. Installing a star layout is simple, inexpensive and fast because of the flexible cable and the modular connector. The number of hubs you can add to a network is limited, but a star layout can support as many as 1,024 nodes. The star layout can operate as an independent workgroup or it can be connected to other workgroups to form a larger network.
Definition
Node- A server, computer, printer, modem,fax machine, auxiliary hard drive or other equipment that is connected to the network device.
Hub- Device whose primary function is to send and receive signals along the network between the nodes connected to it.
10/100BASE-T Cable- A popular Ethernet cable system using twisted-pair wiring with RJ-45 plugs at each end. Category 3Mbps Ethernet networks. Category 5 cable is used with either 10Mbps Ethernet or higher- performance 100Mbps Ethernet.
Mbps- Millions of bits per second, or the amount of data that travels across the cable in 1 second.
Workgroup- Nodes connected to a hub to form a small communication grouping for the purposes of networking. Bus Layout The bus layout connects all computers in the workgroup or network in a single line on a single cable. The data signal is transmitted to the entire population on the cable. A single coaxial (coax) cable is used to connect all pieces of the network. A barrel connector (BNC) is attached to each network adapter card. This allows the cable to connect directly to each computer, then on to the next computer, attaching to the hub's BNC (coax) connector when a hub is used (a hub is not required).
Coax- Cable that resembles TV or antenna cabling, but is rated for network use. There are two types of configurations you can implement using the star or bus layout: client/server.
Peer-to-Peer Network
In a CD-ROM drive, tape backup system and one or more printers. Each node has the ability to talk directly to the node that has the information or service it needs, so resources can be shared within the network.
Client/Server Network
In a star layout, the server is the principal connection point. All nodes, including the server, are connected to a hub. This enables the server to house and administer software, file sharing, file saving, and to allocate printers, fax machines, modems and other communication connections. In a bus layout, the server acts as an arbitrator. Each node talks to the server when requesting information. The server then locates the information, either internally or on one of the connected clients, and sends it to the requesting client.
Higher Performance Networks
There are several ways to increase the performance of your network. If you have an existing 10Mb network or your building is wired only for 10Mb networks, one way to increase the performance is by adding a 10Mb switch. Fast Ethernet or 100Mbps networks provide 10 times the performance of standard Ethernet or 10Mbps networks. A variety of equipment can be used to build a network. Following is a description of basic network components. Network Adapter Cards (also called Network Interface Cards or NICs) provide the link between your computer and your network, converting data from your computer into a format that an Ethernet network can accept. ("Ethernet" refers to the most common set of standards for networking equipment.) Some newer computers have built-in network adapter cards. If yours does not, you can install these small boards in a few minutes. Several types of cards are available; make sure the one you purchase matches the type of slot in your motherboard. Hubs (also called wiring hubs or concentrators) are the central connectivity point in a star workgroup. A hub allows each node to communicate with all other connected nodes. Two or more hubs can be connected, allowing you to expand your network easily and inexpensively. Switches or switching hubs provide dedicated bandwidth for each node resulting in higher network performance. A server is a low- or high-capacity computer that provides various resources to the network. A typical server contains several hard disk drives, a tape backup and a CD-ROM drive. It enables employees to share resources such as printers, fax machines, modems, e-mail and Internet connections. Servers are often used to store database information, files and file backups. Computers connected to the server are called "clients." A print server provides the same connectivity for a printer that a network adapter card provides for a computer. It enables all computers on the network to share the same printer. Print servers are often a basic component of client/server networks.
Communication products include fax cards, modems and routers that allow for Internet connections. All of these products enable you to communicate with computers that are not on your local area network (LAN). A network operating system, or NOS, enables computers and components of the network to communicate with one another. The NOS can range from simple software features built into Windows* 95 to more complicated systems such as Novell IntraNetWare* or Microsoft Windows NT*. Typically a company decides to install its first network because of a need to share files, programs and printers among a few computers. Such basic networks are inexpensive and easy to set up. All you need are a hub, twisted pair cabling, a simple operating system such as Windows 95/98, and network-ready computers (PCs and servers with network adapters installed). As your business grows, your network can expand to meet its new demands. And you can build on your basic equipment rather than starting from scratch each time you add to the network. For example, you can expand a network operating system. Either way, the flexible, modular nature of networking makes it easy for small businesses like yours to "get connected."
How to Wire a Network
Twisted Pair Cabling
Twisted-pair (sometimes known as 10BaseT) is ideal for small, medium, or large networks that need flexibility and the capacity to expand as the number of network users grows. We highly recommend using 10BaseT cabling for its amazing flexibility and reliability. In a twisted-pair network, computers are arranged in a star pattern. Each PC has a twisted-pair cable that runs to a centralized hub. Twisted-pair is generally more reliable than thin coax networks because the hub is capable of correcting data errors and improving the network's overall transmission speed and reliability. Also known as uplinking, hubs can be chained together for even greater expansion.
There are different grades, or categories, of twisted-pair cabling.
Category 5 is the most reliable and widely compatible, and is highly recommended. It runs easily with 10Mbps networks, and is required for Fast Ethernet. You can buy Category 5 cabling that is pre-made, or you can cut & crimp your own. Category 5 cables can be purchased or crimped as either straight-through or crossed. A Category 5 cable has 8 thin, color-coded wires inside that run from one end of the cable to the other. Only wires 1, 2, 3, and 6 are used by Ethernet networks for communication. Although only four wires are used, if the cable has 8 wires, all the wires have to be connected in both jacks.
Straight-through cables are used for connecting computers to a hub. Crossed cables are used for connecting a hub to another hub (there is an exception: some hubs have a built-in uplink port that is crossed internally, which allows you to uplink hubs together with a straight cable instead). In a straight-through cable, wires 1, 2, 3, and 6 at one end of the cable are also wires 1, 2, 3, and 6 at the other end. In a crossed cable, the order of the wires change from one end to the other: wire 1 becomes 3, and 2 becomes 6. To figure out which wire is wire number 1, hold the cable so that the end of the plastic RJ-45 tip (the part that goes into a wall jack first) is facing away from you. Flip the clip so that the copper side faces up (the springy clip will now be parallel to the floor). When looking down on the coppers, wire 1 will be on the far left.
Thin Coax Cabling
Thin coax (also known as 10Base2) is great for small home or office networks with two or three computers. Similar to the cabling used to connect a VCR to a TV set, coax cabling is inexpensive and easy to set up. In a thin coax network, which is sometimes called a backbone, computers are arranged in a "chain" with a beginning and an end. Each computer in a backbone requires a network card, a T-connector, and at least one incoming or outgoing coax cable. The computer at each end of the network will also require a 50-ohm terminator plug
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