Buying the Equipment

Initial Check

If some of the PCs on your network run Windows, you need some Microsoft software. You also need a little bit of Microsoft software to put a Linux PC together. Before you buy any equipment, it's worth checking that you have the software you need.

If you want to connect a Windows PC to your network, you will need a Windows installation CD. When you put a network interface card into a Windows PC, the next time you reboot, Windows will try to install a piece of driver software. This should be supplied with the card on a disk. To complete the installation, Windows will ask for the Windows Installation CD. Until you put that in, the interface card will not work.

If you bought your PC with Windows pre-installed, the supplier should have given you a distribution CD and a recovery disk, but they don't always. This is bad, because you may need to reinstall Windows itself one day. If you don't have the installation CD, you will come unstuck at this point.

If you want to install Linux on a PC and connect it to your network, you will need to run some configuration software. This comes with the interface card, but it runs under DOS, so you need a DOS boot disk. A Windows recovery disk will do.

If you don't have a DOS boot disk and a Windows CD, you will have to get the shop that sells you the interface card to install it for you.

Don't spend money on equipment until you have sorted out this issue.

Parts List

If you only have two PCs, you just need two ethernet interfaces cards and a cat 5 cross-over ethernet cable, about 20 for the lot.

If you have three or more PCs, you will need one ethernet interface card per PC, one straight-through cat 5 cable per PC plus a hub or switch to connect them all together.

You also need some sort of device to connect to the internet and a gateway to control it, but the gateway could be one of your PCs. I discuss these issues in detail later.

If you have the money, a keyboard/video/mouse switch is useful. This allows you control a number of PCs using one keyboard, video screen and mouse. (The keyboard and mouse have to use PS2 connectors. Old ones may not.)

Buying the bits

I live in the UK, so I can recommend some useful suppliers that I found here. If you live elsewhere, you need to shop around.

You can get most of what you need from local shops, but they tend to be expensive and the range is limited. Your local PC World will probably be the most expensive of all, but they are open on a Sunday, which can be very useful.

If you have the time to wait for the delivery, mail order is much cheaper. Micro Mart magazine is a good source of mail order companies. I found Scan in Bolton and Eclipse in Coventry, both doing cheap ethernet cards and cables. The ethernet cards were about 8 each and the cables 2 or 3, depending upon length. In the local shops, the cables are 7 upwards. They had stress relief fitted, which the Scan ones didn't, but you can buy those separately.

When buying mail order, make sure that you are not comparing an ex-VAT price with a VAT price, and watch out for minimum order and delivery charges.

Radio Spares supplies a huge range of electronics parts by mail order. Having bought a set of cheap ethernet cables with no stress relief, I bought clip-on stress relief covers from RS. You can also get ethernet extenders (little boxes that turn two ethernet cables into one long one) cross-over boxes and all sorts of goodies. You can order from RS directly but account customers who make big purchases get much better prices. If you work in engineering, your employer probably has an account and you may be able to place a cash order through that.

Inmac has a smaller range than RS, but they will have most of what you need including a range of keyboard/video/mouse switches.

There's also Black Box and Maplin, which has a few shops in large towns.

If you use NTL's cable modem service, and you opt to buy the modem, you have to do that by mail order. NTL's approved source is a company called Global Direct. (You can rent a cable modem from NTL. Telewest also offer a cable modem service, but renting is the only option.)

I bought my switch and my gateway from Technomatic.

Mail-order goods will come by courier, not the post. If you are not at home when they call, you'll have to go to their depot. If you work, it might be easier to get the package delivered there.

Most ethernet cards sold these days are for modern PCs with a PCI bus. If you have an old PC, you will want an ISA version of the card. PCI PCs usually have a few ISA slots, so you can use an ISA cards in them too.

Ethernet cables are sold ready made with RJ45 terminators. they come in various lengths. Longer ones are a bit more specialist and may be expensive. When you measure up for your cable, be generous. You may want to move the computers around. In any case, you don't want to find on the day that a cable is half a metre short.

Buy spares of cheap items.

You will need an ethernet adaptor card for each computer. Cheap ones cost about 8. "Name Brand" ones like 3COM are a lot more expensive, but may be easier to configure. Once you have got them configured, cheap cards perform as well as expensive ones.

Most of the cards you can get now support 10base-T and 100base-T, which means that they run at 10 Mbit/sec and 100 Mbit/sec respectively. 100base-T is also known as fast ethernet. These are nominal speeds. The real speeds are 30%-60% of that. For a home installation, 10Mbps is ample. Most 100base-T cards claim to be auto-sensing, which means that they figure out what speed the equipment they are connected to will handle, and run at that. With the cheap cards, it doesn't always seem to work and you have to force them to the right speed when you install them.

Whatever interface card you buy, get the supplier to verify that the card is compatible with the operating systems you plan to use - Windows XP, Windows 98, Linux or whatever. If it then isn't, they should refund your money, or replace the card and bear the postal costs. (For this kind of reason, I try to order goods by telephone rather than through the web.)

You can build your network using an ethernet hub (sometimes called a repeater) or an ethernet switch. These have RJ45 sockets called ports, so you may see an ad for a "sixteen port dual-speed auto-sensing ethernet switch". You will need one port per computer, plus one for the gateway. In both cases, each port on the hub or switch is connected to one computer at the other end of an ethernet cable. The cable are category 5 Unshielded Twisted Pair (UTP) patch cable, terminated at each end with RJ45 connectors. (You may also see more expensive Shielded Twisted Pair (STP) patch cable which has an earthed sheath wrapped around the cable. You don't need this and your switch may not even supply the necessary earth connection to make it work.)

If you use a hub, all the connected network cards have to run at the same speed. I built my first network this way. The ethernet connection on my cable modem only runs at 10Mbps, so the whole network was restricted to that speed. This is ample for a small network,

These days, a dual-speed auto-sensing switch only costs a few pounds more than a hub.

A cable gets stressed in use, and it can develop small breaks at the end, where it joins. This fault can be very difficult to track down, because the problem goes away when you touch the cable. To avoid breaks, buy cables with stress relief, or fit stress relief covers.

If you are not careful you'll end up with a mess of tangled cables. Try to be tidy - roll up any excess cable and tie string around the loop, or use proper cable ties. Number the cables and label both ends. Label the ports on your hub or switch to show which computer is at the other end.

Plugging the bits together

There are two flavours of cat 5 cable, straight and cross-over. The cable is multi-cored, with different wires used for different purposes. A hub and a cable modem are transmission devices. Computers are terminal devices. A transmission device sends out data on the wire that the terminal device at the other end expects to receive it on. In the same way, it expects to receive data on the wire that the terminal sends it on. What the hub regards as the transmit wire, the computer regards as the receive wire, and vice versa.

If you connect two computers (terminal devices) together without a hub, you need a cross-over cable, so that the send wire on one end is connected to the receive wire on the other. The same goes if you connect two transmission devices together, a hub to a hub, or a hub to a cable modem.

Most ethernet cards and hubs have a little green light that lights up steady when the connection is good, and blinks when data is transmitted. If you need a cross-over cable and you use a straight-through, or vice-versa, the green lights will not go on.

Computers networks eat mains sockets so I mounted a switched mains gang connector on the wall to run the hub, the gateway and the cable modem. The one switch starts them all up and shuts them all down, which is very useful.

Building the LAN is easy. For just two computers, fit and configure the ethernet adaptor cards (see later). connect them together with a single cross-over cat 5 cable. If you are using a hub or switch, fit and configure the adaptor cards, and connect each to a port on the hub via a straight-through cable.

Your broadband connection device (cable modem or ADSL) can also connect via ethernet. Connecting to this is covered in the section on gateways.

You usually only need one cross-over connection out of a hub, so some have a push-button that crosses over the wires inside one of the ports. The literature for my hub says "push-button uplink port simplifies cascading with other hubs using standard UTP cables to connect additional users". Hmm, yes. Anyhow, if your hub has a button on it, that's usually what it does: turns one of the ports into a cross-over, so that you can connect it to another hub using an ordinary straight-through cable.

If you buy an ethernet cable modem, there will be a cat 5 cable in the box to connect to it. The manufacturer might assume that you will plug it directly into a computer, and supply a straight-through cable, or they may supply two cables, one of each type, leading to endless confusion. (Look for an "X" printed on the cable. That indicates that it's a cross-over.)