More than just connecting the wires: it takes a serious plan to perfect a LAN

Black Enterprise, Feb, 1998 by Tariq K. Muhammad

Last month, we explained how to assess your network readiness and gave tips on deciding between a ear-to-peer and client/server network. Now it's time to get into hardware solutions. There are times when upgrading your system is just a matter of popping a floppy disk or CD-ROM into the computer and pointing and clicking your way through the process. This isn't one of them. Unless you have experience under the hood of a computer and more than a passing interest in network operating systems, it is wise to enlist the help of someone who has dealt with the idiosyncrasies of computer networking.

If you are the do-it-yourself type and have decided on a peer-to-peer network, you may want to tackle this job yourself A peer-to-peer network is the easiest to implement--especially if you're connecting only two computers. PCs and Macs can establish a direct connection between two computers simply by linking the serial ports with a serial cable.

For more than two computers, it's somewhat different. Each machine you plan to connect will need a network interface card (NIC), which plugs into an expansion slot on your computer's motherboard and determines the method of access to the network. Depending on the original configuration of your computer, you may already have one installed. If not, it will cost between $100 and $200.

If you're still using Windows 3.x, you'll have to upgrade your operating system to be able to deploy a peer-to peer network. Microsoft has discontinued production of Windows for Workgroups and Win 3.x, so Win 95 is probably the best current choice for Windows users. However, if you're absolutely opposed to Win 95, products such as Artisoft's LANtastic will enable Win 3.x machines to peer network. Once the NICs have been installed, the final step is to connect the PCs with cabling that plugs directly into the NIC. Both the Mac/OS and Win 95 are plug and play, so you should be ready to share resources once you've installed an NIC and rebooted your machines.

Installing a client/server network is more complicated. If you are connecting more than two computers, you must decide on the topology of your network before you get to the hardware or software. Topology is the pattern of interconnection between PCs, which determines (among other things) what kind of NIC you will need. Sometimes the topology you use will be determined by physical constraints such as the distance between the computers to be networked.

Bus, ring and star are the three basic topologies for networks, each with its own benefits and drawbacks. Bus and star topologies require Ethernet NICs, while ring-based networks require a Token Ring NIC. Ethernet and Token Ring are the two most commonly used network access methods, although some newer methods use a combination of the two. An Ethernet network is less expensive to deploy, hence its greater popularity.

There are also three basic kinds of Ethernet cabling: coaxial, which has thick and thin varieties (thick coaxial can connect devices at a distance of no more than 1,640 ft. and thin coaxial has a maximum reach of 607 ft.); twisted pair, which resembles telephone wire and is reliable up to 328 ft.; and fiber optic, which has a limitation of 1.2 miles.

In the bus system, PCs on a network are connected to a single cable similar to branches on a tree. This method of connection is best for low-volume networks because the main cable is limited by its bandwidth. As the number of clients or volume of information increases, performance slows. Installing the wrong cabling can bring your network to a crawl.

Like the bus, the ring topology uses a single cable, but one that is looped rather than open-ended. Also called Token Ring, it differs from the bus method in another important aspect. Rather than waiting in line and re transmitting garbled data, clients pass an electronic signal, called a token, between one another that clears the recipient to send or receive data. The star topology dictates that each PC is connected to the server via its own dedicated line, resembling a five- (or more) pointed star. It a lows important network resources to be centralized and eases network management.

Picking a topology for your network will be a determining factor in its performance. Since networking needs vary among companies, it is nearly impossible to suggest an overall best choice. Consult a professional and ask which will serve your business environment best. For more on LAN topologies, read LAN Tutorial, edited by Steve Steinke (Miller Freeman Publications Inc., $26.95).