Networking Your Home
Created | Updated Jan 28, 2002
Time was when home networks were the province of the irredeemably sad, but in these days of enlightenment (or at least, since the new PC arrived and the old one was given to the kids) the posession of more than one computer in the home has become common even for those who have a life.
Of course, this raises immediate problems regarding Internet access. The arguments over long phone calls with boyfriend / girlfriend pale into insignificance compared with the ructions which can be caused by (a) huge Internet phone bills and (b) who gets to use the phone line at any one time.
The simple solution is a home network. Pause for astonished gasps and sounds of fainting. No, it's not difficult and yes it's very cheap. If you want to be able to use the Internet from two machines at once in your house, read on.Warning: This article uses technical terms. Definitions are listed at the bottom, but for a more comprehensive reference you could try Imperial College's Free Online Dictionary Of Computing. The products and technologies discussed here are widely available, for surprisingly low prices, from high street computer specialists and PC World. This is not rocket science, and is well within the capabilities of anyone who can keep Windows 98 running for more than about 4 hours without crashing. OK, that hurdle is a bit high. Anyone who has Windows 95 whose screen doesn't flicker.
The Basics
In the old days, PC users could use a serial cable and a piece of software called LapLink to connect two computers. With Windows 95, it became possible to use a serial or parallel cable and no additional software. Mac users never needed any software; the Mac has supported networking using it's Appletalk feature from a very early stage, and a printer cable was usually all that was required.
These days, however, this is not generally adequate. Files are bigger (especially if you use Microsoft Office, which seems designed to keep manufacturers of hard disks in business) and people are less prepared to wait. So the starting point is generally an Ethernet connection. This gives you several benefits including:
- Internet connection sharing
- File sharing
- Printer sharing
- Ability to back up all computers onto a tape installed in one computer
From this point it all starts to sound technical, so first of all may I suggest you close your eyes (no, not now, you haven't finished the paragraph, wait until I've told you what to do!) right, close your eyes and chant "I can do this!" until (a) you believe it or (b) people start giving you funny looks (OK, I know, you can't tell, because your eyes are shut - I hate pedants).
Ethernet
Ethernet has been around for some time now so is well supported by almost every operating system and computer, unless it's really old.
Twisted Pair Cable
The most common form of ethernet these days is 10baseT, which carried over unshielded twisted pair (UTP) cables, generally referred to as Category 5, or Cat 5 for short. Category 3 is all that's required for most installations, but the cost and inconvenience of cabling is such that few people bother, and most put in the higher-specification cabling which is more future-proof.
The advantage of using twisted pair is that it's very widely available, it will carry other traffic (e.g. ISDN) and cards are extraordinarily cheap. The downside is that you almost invariably need a hub (see below). Although you can use a "crossover cable" to connect two computers, if you want to add another computer or device you must have a hub, so you might as well plan for it at the start.
Coaxial Cable
Another fairly common form of Ethernet is 10base2, or thin ethernet (also thin-net). This is a coaxial cable somewhat thinner than that used for TV aerials, with a bayonet connector ("BNC") crimped onto the end. To attach this to a card you need a T-piece and a terminator. Although connecting straight to the BNC connector on the network card might work, it's fairly unlikely and the specification calls for the additional bits.
The big advantage of thinnet is simplicity. It requires no hubs - you just start with a terminator at one end of the cable, connect as many PCs as you like along its length, and finish with a terminator at the other end. Dead easy. The downside is that the cable is relatively expensive, you can't use 100 megabit (which is really irrelevant in a home context), the cable is more susceptible to damage, you need terminators and T pieces, and the cards are slightly less common. This sounds like a big deal, but in practice thinnet is still very cheap and easy enough for the complete novice.
Wireless Ethernet
Wireless ethernet has been around for some time, but until recently was prohibitively expensive for home use. Recently, though, wirless networking solutions like Apple's AirDock have become more affordable. Although bandwidth is lower than wired ethernet (typically 2GBit or less) this is, as has been discussed elsewhere, not generally an issue in a home setting. Cabling is, however, and the fact that wireless ethernet, as its name suggests, requires no cabling must make it a strong contender where budgets permit.
What you need
Let's assume you're going with Ethernet, as being the most practical and cost-effective solution.
Each computer to be connected needs an ethernet card. There are a few things you need to check before buying an ethernet card:
- Have you already got on-board ethernet? Most newer Macs and some PCs have ethernet on the motherboard. Older Macs need a thing called a transciever to connect to the proprietary (AAUI) socket, later ones have a standard RJ45 socket.
- Have you got a spare expansion slot, and if so what type? New PCs and Macs usually have PCI slots, older PCs will have larger ISA, MCA or EISA slots, and Macs may have either an LC expansion slot, or a NuBus slot. If in doubt take the computer to a proper computer shop (or, in dire emergency, PC World) and have them specify the card.
- Are the computers within the specified cable run length. Unless you have an unusually large house, you'll be OK here - 100m for twisted pair, 200m for thinnet.
- Which type of cable will you use? Or will you start with thinnet, but preserve your options for later upgrade to twisted pair, in which case you buy a "tri-media" card (not actually that much dearer, but rarely support 100 Mbit)
- Does your operating system support the type of card? Make sure the card comes with drivers certified by Microsoft (or Apple, or whoever) for your operating system. If you're running Windows 3.x, this is particularly important.
Choosing cable type
Thinnet is very very easy. Trivial to cable, and simple to maintain. Give serious consideration to using this if you have a small number of devices (two or three computers) and are unlikely to add complicated things like routers (ADSL or ISDN). It's marginally less flexible (in the sense of giving you choices) than UTP, but definitely still a good choice for most home users.
If, on the other hand, you are already considering things like multi-user ADSL, networked games (notoriously high bandwidth requirements) or you already have RJ-45 sockets on your computers, then 10baseT or 100baseTX is for you (the cabling is, to all intents and purposes, the same for both).
Measure the distances, and take account of obstacles and so on. No cable likes being run under carpets and walked over, but you can tuck the cable down the edge of a carpet to get it out of sight. Surface trunking (which sticks on the wall) is commonly used, but ugly. If you have suspended wooden floors you are lucky - a small hole and the cable is out of sight.
The hardest part is getting cables long enough to run between rooms or floors. Check your local specialist computer shop and see if they'll make them up specially. One 50m Cat5 certified lead is probably all you'll need to connect to the bedroom upstairs; other devices will be clustered around the hub so you can use shorter, standard patch leads.
Finally, decide whether to buy a hub. And the answer here is, if you use twisted pair, almost certainly yes. You can get away with a crossover cable, but then you can't add any additional devices to your network. If you don't buy a hub, remember to get your special long cable made up as a crossover - and remember that it won't work with a hub if you buy one later!
Structured Cabling
Some modern houses have structured cabling fitted, like in offices, and some sad types actually install this in older houses as well. Structured cabling is a system where RJ45 sockets are placed around the house, and cabled back using (generally) Cat.5 or Cat.6 cable, to a "patch panel" (an array of sockets). This cabling will carry ethernet, telephone, ISDN and various other sorts of traffic.
There is one massive advantage to structured cabling: you can connect a phone or computer almost anywhere in the house. You can plug your PC into the wall, and connect the associated port on the patch panel, into the hub, so your hubs and stuff can be placed conveniently out of sight under the stairs. The downside is that it's fairly expensive (budget around £300 for an average house, plus the cost of hiring a cable tester), requires special tools, it's disruptive while you do it, and it reveals to all who care to know (although realistically this is likely to be fa fairly small audience) that you are a nerd. It could be said that if you craed about that you wouldn't be doing it, though......
Installing cards
Installing cards is usually simple. Newer operating systems (and virtually all Macs) offer "plug and play" detection of new hardware. Plug the card in, and the drivers install themselves. Notable exceptions include Windows NT. For non-plug and play operating systems, you will need to follow the manufacturers' instructions with the card and install the drivers (usually from a "floppy disk," an archaic form of removable media)
Before you start, protect against static. Get a wrist-strap and connect it to the metal chassis of the PC. Leave the PC plugged into the mains, as the earth pin grounds the chassis and reduces the risk of grounding, but ensure the PC is switched off before opening the lid or inserting cards.
Some PC manufacturers will try to persuade you that you will invalidate the warranty if you open the case of the PC. This is almost certainly legally unenforceable, as adding a component is a normal part of owning a PC, but if you have a newish PC or one with an extended warranty (the Hewlett packard and Dell support packs, for example, offer three years' on-site support for an amazingly reasonable price) then it makes sense to contact the manufacturer and probably buy the network card from them.
And if the idea of opening the lid of your cherished piece of technology sounds daunting, most decent PC shops (and PC World) will fit network cards for you. This has the additional advantage that if they supply and fit the card, they are responsible if it doesn't work, which can save hours of argument later.
Using Your New Network
So, you've installed the network cards, plugged them into the cabling (and maybe the hub), and turned the PC on. Will it work? Probably. If not, check that the green pilot lights are on (most network cards and hubs have a green LED which lights up when a conneciton is correctly made). If the lights are out, try swapping the cables. Note: on a tri-media card, the green light is commonly attached only to the UTP interface, so if you're using BNC you will probably not have a pilot light even if the card has one fitted).
The precise details of troubleshooting network connections are well beyond the scope of this discussion, but suffice it to say that normally it does just work.
IP Addresses
Every computer onm the Iternet has a unique Internet Protocol (IP) address. Which is great, but how do you get one? Answer: you don't. Your ISP assigns one to you when you dial up. For your own computers to talk to each other they will need unique addresses of their own. So you need to use the networking controls to assign addresses, and more importantly you need some addresses which won't cause problems.
First, if you buy something like an ISDN router to connect to the Net, it will usually do this for you automagically using something called Dynamic Host Configuration Protocol (DHCP). If not, then you need to choose one of the "private" IP adress ranges. The most common is probably 192.168.0.x - so your computers could be 192.168.0.1, 192.168.0.2, 192.168.0.3 and so on. The subnet mask to use would be 255.255.255.0. A discussion of exactly why is well beyond the scope of this discussion, but it's all to do with binary arithmetic.
So, how do you share the Internet connection? One way is with Windows' Internet Connection Sharing, set up through the dial-up networking control. Another is to get a thing called a "proxy server" (e.g. WinGate) which will manage your network connections for you. Both will use something called "Network Address Translation" (NAT) to manage the traffic from several internal IP addresses to one external address, assigned by your ISP. If you have a router, it will probably do thie same.
One way or another, one device (router or computer) will connect to the Internet, and it will provide services to the others. One good reason for using a proxy server is that it can cache some traffic and reduce connection times; it also allows you to define the access levels for individual members of your household. Most proxy server software will include some basic content filtering
Safety First!
Whatever you do, it is very strongly advised that you have firewall software on your PCs if they are connected to the Internet. If you're not convinced go to Gibson Research Corporation's ShieldsUp! site. Note, though, that his views on trojans are controversial - you are better off not worrying about trojans in the context of firewalls, and instead installing a high-quality virus scanner which will clean infected email attachments vefore trojans can be installed.
Glossary
| 10base2 | The variant of Ethernet which is carried on thin coaxial cable. "10" means 10Mbit, "base" is short for baseband (a technical term for fixed-frequency digital signals, where normally only one channel is available at any one time) and "2" signifies a maximum cable run of 200m. |
| 10base5 | Thick Ethernet, uses thicker cable than 10base2, and has a maximum cable run of 500m. |
| 10baseT | A variant of Ethernet which is carried over twisted-pair cabling (Cat.3 or Cat.5). Maximum data rate is 10Mbit, and "T" means twisted pair. Maximum cable run is 100m. |
| 100baseTX | The most common form of fast (100 Mbit) Ethernet, will run over standard unmodified Cat.5 cabling - hence it's popularity. |
| Category 3 (Cat.3) | A US standard for (originally) voice-grade cabling, which will support standard 10 Mbit ethernet. Not widely used these days as Cat.5 is not much dearer once installation costs are taken into account. |
| Category 5 (Cat.5) | A US (and international) standard for voice and data cabling. Cabling which is Cat.5 compliant will carry 10baseT and 100baseTX traffic. In Cat 5, eight conductors are arranged as four pairs, twisted along their length to reduce inductive effects and crosstalk between pairs. In UTP cabling, there is no screen around the cables, so if you try to pass signals above a certain frequency you can cause interference on adjacent cables. Hence, in newer installations, shielded twisted pair (Cat.6) is often used. This has a foil screen around the cables which is earthed at one end to ground out electromagnetic noise. This is especially important in offices where the same cabling is used for data and telephone traffic (known as structured cabling). |
| EISA | Extended Industry-Standard Architecture. One of several competing 32-bit expansion slot specifications, this one eventually won because it would accept old-style 16-bit cards as well. |
| Firewall | Software or hardware product which prevents unauthorised traffic - for example, it might block incoming traffic from the Internet onto your network. |
| Hub | A device which turns several twisted pair cables into a network. Connect two PCs to a hub via Cat.5 drop cables, and they should be able to communicate. Available with different numbers of ports, 4-port and 8-port are the most common in home use. |
| IAS | Industry Standard Architecture. Pause for uncontrollable laughter at the idea of an "industry standard" amongst PC manufacturers. A specification for 16-bit expansion ports on PCs. |
| MCA | Micro-Channel Architecture. IBM, in it's infinite wisdom, designed this 32-bit expansion slot for it's PS/2 range. While it was technically superior to the competing EISA specification, old cards would not fit in the new slots, so takeup was limited. Think of it as betamax for PCs. |
| PCI | Peripheral Component Interconnect - a specification for expansion slots in computers. |
| Proxy; Proxy Server | A software or software and hardware product which allows you to share an internet connection. WinGate make a good proxy server. You tell your browser to use the proxy as its internet connection, then the proxy server does all the fetching and carrying, generally on another machine. The advantage is that the proxy server removes the direct connection to the internet fomr your workstations, and can cache and even read-ahead your web content to improve performance. |
| RJ-11 | US standard for telephone plugs and sockets. A 6-wire system, you will find an RJ-11 socket on almost every modem ever made. Older Mac networks also use this specification, especially when using products such as Farallon's PhoneNet. |
| RJ-45 | The plug and socket specification used in twisted-pair ethernet installations. RJ-45 is an 8-wire connection, yet it's only around 10mm wide. RJ-45 sockets will also accept RJ-11 plugs (but not vice-versa). |
| Router | A thing which seamlessly transfers network traffic form one network to another. The most common application in a home context would be an ISDN router, which transfers traffic between your network and the Internet via a dial-up ISDN connection. You never see the connection being made, and the delay is imperceptible; to the user, it feels as if you have a permanent connection to the Net. |
| Switch | A switch is like a hub, but instead of individual packets essentially arguing it out trying to get onto a single wire (which is how a hub works, rather like a series of side roads feeding into a main road), the switch manages traffic between network segments. The ethernet equivalent of traffic lights. |
