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Author: Radish Big gold star, 5000 posts Old School Fool Add to my Favorite Fools Ignore this person (you won't see their posts anymore) Number: of 190784  
Subject: Home Networking, Part 1 Date: 1/7/2002 1:19 AM
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Home Networking, Part 1


What is home networking and why would you want to do it?
First of all, if you only have one computer at home, then you can skip reading this. But if you have two or more, you might want to connect them together and form your very own home network, or LAN (Local Area Network). You can even tie your LAN into a WAN (Wide Area Network) such as the Internet.

The three most common uses for a home network are: sharing files, sharing printers, and sharing an Internet connection. More on each of these below.

The two most common ways to connect computers together are: twisted-pair cabling (10BaseT and 100BaseT Ethernet) and wireless (WiFi, also known as IEEE 802.11b). There are many other ways, but because they are less popular, or are from older standards being phased out, this document only covers these two methods.

In either case, every computer needs a NIC (Network Interface Card). You can get NIC's that plug inside the computer (using the ISA or PCI bus), that plug into a laptop (using a PCMCIA card, also unfortunately called PC card), or that connect to your computer's USB port. Each computer can use a wired or a wireless NIC.

This “part 1” gives the overview and then describes how to hook everything up. Part 2 tells how to set up Windows 98 or Windows 2000.

File sharing
When you have computers connected in a home network, you can “share” any folder on any of the computers. Once you set a folder as shared, the other computers on your LAN can read all the files in that folder. You can also set the folder so that other computers can change the files in the folder, or store new files there. And you can protect the shared folder with a password, to limit access to certain people (or computers).

Obviously, it is easier to move or copy a file from one computer to another by sending across a network than by using floppies or other removable media and carrying it over. It's fast, too. Subtracting 20% as a rough estimate of overhead, a 10BaseT network can send a megabyte per second; and a 100BaseT network sends 10 megabytes per second. (The actual speed varies depending on a number of factors, especially on the number of computers using the same wire at the same time.)

Another popular use of file sharing is doing quick and easy backups. You can back up the data on one computer to the hard drive of another computer. If the hard drive of one computer fails (or even if the entire computer dies), the data is still available from the backup on another computer's hard drive. There is some risk of a common calamity wiping out several computers (like lightning, fire, or theft), so it's not a secure as, say, doing backups to tape or CD and taking them to your safe-deposit box. But it's so much more convenient, you may do it more often. In fact a combination of techniques — doing a full backup to tape or CD and storing that outside the house, and doing a “differential backup” (of only files that have been changed since the full backup) over your LAN to another computer — can be so fast that a routine backup can take just minutes. Also, some popular programs (like Quicken, for example) have an option to back up your data occasionally when you exit the program, and most of these can write the backup to another computer over your LAN.

Printer sharing
There's really not much to say about this. If you so choose, all the computers on your LAN can print to any of the printers. In order to print to a printer that's on another computer, the printer must be set as “shared”, and the computer it's connected to must be on. Probably a good idea if the printer's on, too.

There are also printers that can connect directly to an Ethernet LAN, so they can be used by any computer without having to have one particular computer on. And for printers that don't have that feature, you can get a gadget to connect it onto your LAN. Also, if you're sharing an Internet connection, the equipment used to do that may include a printer connection.

Internet sharing
Although any type of Internet connection can be shared on your LAN, usually people share the faster connections (DSL or cable modems) rather than the slower ones (dial-up). The connection can be shared either with hardware (usually a “broadband router”) or with software (usually a “proxy server”). Sharing a connection with software is more complicated, and requires the computer running the software to be on whenever any computer needs Internet access. And as DSL and cable modems have become more popular, the cost of broadband routers has dropped dramatically, making them by far the most popular method of sharing an Internet connection on a LAN. (What I'm hinting at here is, despite that you might want to use software because it's cheaper, I'm not going to cover that in this document.)

DSL modems and cable modems often come in different versions: Ethernet, USB, and internal card. The Ethernet version is what you want for your home LAN. USB modems are relatively new, and you may not be able to connect them into a home LAN easily. A modem on an internal card, as the name implies, plugs directly inside a computer; this makes it very difficult to connect to a LAN (in other words, avoid this, and I'm not explaining how to make that work here).

In some cases, your ISP will let you connect multiple computers to your LAN for no extra fee. This may or may not make things easier for you, depending on what else you want to do with your home LAN. More often, your ISP will want to charge an extra monthly fee for additional computers. In some cases, your ISP won't want you to connect additional computers at all. A broadband router can make several computers appear as if they are a single computer to your DSL or cable modem, thus eliminating any extra fee (although there may still be a legal problem if your service agreement forbids you to connect multiple computers).

Incidentally, the speed of a modem or Internet connection is given in either kilobits per second (Kbps) or megabits per second (Mbps). Dial up connections are usually given in Kbps (so a “33.6” modem operates at a maximum speed of 33.6 Kbps). Divide Kbps numbers by 1000 to get Mbps speeds (so 33.6 Kbps equals 0.0336 Mbps). Ethernet speeds are almost always given in megabits per second (for example, 10BaseT operates at 10 Mbps). The general speed range for non-dial-up connections is from 128Kbps (0.128 Mbps) to as much as single-digit megabit numbers (like 3000 Kbps or 3 Mbps). Often the “downlink” speed (the speed of data coming to your computer) is higher than the “uplink” speed (the speed of data you're sending).

Where to get the gear
Linksys is a popular manufacturer. http://www.linksys.com I'll be giving some model numbers for particular equipment in each section. Another popular manufacturer is SMC (formerly Standard MicroSystems). http://www.smc.com/smc/pages_html/homef.html Again, I'll be giving specific model numbers. Note that models do change, and new models are added, so check out the websites. Yet another popular manufacturer is D-Link. http://www.dlink.com I'm not as familiar with them, and they have a zillion models, so you're on your own for selecting from their products.

You can find all three companies' products through various pricing websites, like http://shopper.cnet.com/ Just type in the model number to search for a vendor. And of course you can check popular websites like http://www.buy.com http://www.outpost.com and http://www.computers4sure.com

Cables, plugs, jacks, and wire can also be found at stores like Home Depot and Lowe's. But they'll probably be cheaper from one of the sites listed above.

Connecting your computers — wireless
You can connect your computers together either with twisted-pair cable, or using wireless technology. Wireless is easier, especially if the computers are not in the same room but are still fairly close together, but it is more expensive. Wireless can also let you roam the house, and even sit out on the porch, with your laptop while you use the Internet. And if your neighbors are close enough, you can re-sell your DSL or cable Internet connection to them using wireless (this may not be exactly legal, though).

There are a number of wireless technologies, but WiFi (or IEEE 802.11b) has quickly become the most popular, and it is clear that some of the competing schemes are going to become obsolete soon. In theory, WiFi equipment from different manufacturers will work together in your network. In practice, I'd recommend sticking to one manufacturer for now unless there's a really compelling reason not to.

Wireless is not as fast as wired networks, but it may be completely adequate for your needs (especially if you're sharing an Internet connection, or printers, rather than sharing files). WiFi operates at several different speeds, depending on the distance and the proximity of conflicting devices transmitting on the same frequencies (such as cordless phones, microwave ovens, or your neighbor's WiFi network). The speeds are: 11Mbps (distances of 82 to 524 feet, depending on conditions), 5.5Mbps (115 to 886 feet), 2Mbps (148 to 1312 feet), and 1Mbps (180 to 1500 feet).

Often when you use wireless, you will also connect one or more computers using twisted-pair cable. So you may need to read a little of that section as well. You can save money (and get faster connections) by arranging your network so you use wired connections for as many computers as it's easy to connect that way, and saving the wireless method for the more difficult locations.

Wireless — choosing an access point or router
The first step is to choose between a Wireless Access Point or a Wireless Broadband Router. You'll need one or the other. The router does everything the access point does, plus lets several computers appear to be a single computer to a DSL modem or cable modem. Choose the router if you need that capability, or envision needing it in the future.

Typically Access Points have provisions for connecting to one wired computer or a DSL or cable modem, whereas Broadband Routers have a connection for a DSL or cable modem plus one or more wired computers. If you wish to connect a DSL or cable modem and one or more wired computers to an Access Point — or if you wish to connect more wired computers to a Broadband Router than it has provisions for — you can do that using a hub or switch (see the section on wired connections). Note that in either case, to connect a DSL modem or cable modem, it must be the type that has a 10BaseT Ethernet connection.

Model numbers: Linksys's Wireless Access Point is model SAP11 (note that this device may need to be connected temporarily to a computer using USB in order to configure). Their Wireless Broadband Routers are BEFW11S4 (with connection for 4 wired computers) and BEFW11P1 (with connection for 1 wired computer and 1 printer). SMC's Wireless Access Point is model SMC2655W. Their Wireless Broadband Router is SMC7004AWBR (with connection for 3 wired computers and 1 printer).

The Broadband Routers have a WAN jack that connects to your DSL or cable modem (if you have one) using a 10BaseT twisted-pair Ethernet cable, and one or more LAN jacks that can connect to computers (again, using a twisted-pair Ethernet cable, see the wired section below). Some Broadband Routers have a serial-port WAN jack that can be used for ISDN service (which is a DSL-like service, but slower and available in more areas), or with a regular modem and dial-up service (which can be handy if your DSL or cable service is down). The Access Points have a single jack that can connect to either a DSL/cable modem, or to one computer. All these products are fairly easy to connect, simply follow the instructions that come with them.

Wireless — NIC's
Next, you need to connect each computer using either a wired connection (see the wired section below) or a wireless NIC. Wireless NIC's are available in PCI (plugs directly inside your desktop computer), PCMCIA (also called PC Card, for laptops), or USB. The PCI cards are actually just adapters that let you plug the PCMCIA wireless laptop NIC into your desktop.

Linksys model numbers are WDT11 for PCI (a WPC11 is also required), WPC11 for PCMCIA, or WUSB11 for USB. SMC model numbers are SMC2602W for PCI, SMC2632W for PCMCIA, or SMC2662W for USB.

Again, these are easy to install and come with instructions (note that the PCI cards require you to open your computer's case and use screwdrivers and stuff).

Connecting your computers — wired
There are two widely used Ethernet standards: 10BaseT and 100BaseT (also called Fast Ethernet). They are very similar, the main difference being that 100BaseT is ten times as fast and more picky about the type of wiring used and the distances. You can even combine 10BaseT and 100BaseT with little difficulty.

The general scheme is that the computers do not connect directly to each other. Each computer has a cable that runs to a gadget with lots of jacks: either a hub or a switch. I'll get into the details further on.

Wired — NIC's and cables
First, each computer that's going to be wired into your LAN needs a NIC. Nearly all modern NIC's automatically adjust to use either 10BaseT or 100BaseT. They are available in PCI (plugs directly inside your desktop computer), PCMCIA (also called PC Card, for laptops), or USB. 10BaseT-only NIC's are also available in ISA for older desktop computers.

Note that many computers have an Ethernet NIC built-in. It is easily identified by the RJ45 jack, which looks like a telephone wall jack but it slightly wider (it has 8 conductors, whereas telephone jacks have room for 6 but usually have only 4 or 2 in place).

There are many vendors for NIC's. I doubt there's any huge difference between different brands. Use a brand you're familiar with, or search one of the pricing websites, such as http://shopper.cnet.com/shopping/0-11022-301-0-0.html?tag=st.sh.1372-301-0.lst.list_11022 A brand I've used and had good luck with is SMC http://www.smc.com/smc/pages_html/homef.html

10BaseT and 100BaseT use UTP (Unshielded Twisted-Pair) cable, which is just cable where the 4 (or 8) conductors are twisted together into 2 (or 4) pairs. Both use 2 pairs (4 conductors), but are often wired with 4 pair cable for no apparent reason. One pair is used for transmitted data and the other for received data. The twisting helps keep the wire from picking up (and giving off) radio signals (because as the radio signal hits the wire, it induces a positive voltage at one point, but then at a nearby point after a twist the wiring is reversed, inducing a negative voltage; the positive and negative voltages cancel each other out to some degree). It also keeps one pair from leaking signals into an adjacent pair (or reduces that, anyway). Higher frequencies are physically smaller than lower frequencies, so for the twisting to be effective at higher frequencies there needs to be more twists per inch. Cables have been standardized by “categories” which primarily relate to the number of twists per inch. 10BaseT requires category 3 cable (also called CAT3) and 100BaseT requires category 5 cable (CAT5). You can also use any higher categorization, so CAT5 cable can be used for both 10BaseT and 100BaseT. 10BaseT is actually somewhat forgiving about this, and you may even get reasonable results using untwisted cable (like old-style phone wire) over short distances.

You can buy ready-made cables that already have the RJ45 plugs on each end. (RJ stands for “registered jack”, from the old Bell phone company days, 45 just means this was the 45th jack added to the registration list.) Mostly the cables sold today will either be CAT5 or CAT5e [an “enhanced” CAT5 which may also be used for gigabit-per-second Ethernet] and thus will work for both 10BaseT and 100BaseT. These are ideal for use between equipment located in one room. You can also buy the cable and put the ends on yourself; and you can use wall-mount jacks and run cables inside the walls. I think the details on making your own cables are a bit beyond what we want to get into here.

There are actually two different types of Ethernet jacks even though they both use the RJ45 jack that looks like a big phone jack. The one used on NIC's always has the transmit pair on pins 1 and 2 and the receive pair on pins 3 and 6 (with odd numbered pins positive and even numbered pins negative). The jacks on switches and hubs (and many DSL and cable modems) are wired the other way (with transmit on pins 3 and 6, and receive on pins 1 and 2). That way the data transmitted by your computer on pins 1 and 2 goes into the receive connections of the hub (still on pins 1 and 2). Obviously, a standard cable has all the pins connected “straight through” (that is, pin 1 to pin 1, pin 2 to pin 2, and so on).

Except for “crossovers”. There are cables that are called crossover cables, where each wire-pair connects to transmit (pins 1 and 2) on one end and receive (pins 3 and 6) on the other. You could use a cable like this to connect two computers together without any other equipment — but you wouldn't be able to connect in a third computer this way. Besides crossover cables, there are crossover jacks on some hubs, switches, and modems. It may be labeled crossover, X, uplink, daisy-chain, or something like that (on a modem, it may not be specially labeled at all). And it may be shared with a regular jack (for example, a 5-port hub may have jacks labeled 1 through 5 and one labeled 5X, in which case you can use the 5 jack or the 5X jack but not both at the same time). Or there may be a switch that selects whether a jack is wired normal or crossover.

So here's the cable rules. When you connect a NIC to a hub/switch/modem, you use a normal (or “straight-through”) cable. When you connect two NIC's together, or connect two hub/switch/modems together, you use a crossover cable (but you probably won't need to do this). EXCEPT: pretend that a crossover jack on a hub/switch/modem is a jack on a NIC. It's OK to experiment if you don't know whether a jack or cable is regular or crossover; you won't burn anything out. And most NIC's have a light (and most hubs/switches a light for each port) to tell you whether the connection is working or not.

Wired — hubs and switches
Hubs and switches are similar — they have a bunch of jacks (called “ports”) that you can plug computers or modems into — but they work in different ways. A hub basically just connects all the jacks together. The data transmitted into one jack comes out on all the jacks. This means the speed (10 Mbps with 10BaseT or 100 Mbps with 100BaseT) is shared by everything connected to the hub. It also means you can't connect both 10BaseT and 100BaseT to the same hub (although there are some quasi-hubs that do have this feature).

A switch looks at where the data is supposed to be going, and sends it to the correct jack. So data transmitted into a given jack does not go out to every jack, it goes out the proper jack for the device the transmission is intended to reach. (Although occasionally a computer will “broadcast” data to all other computers, so that does appear on all jacks.) This means that, for example with 100BaseT, two computers could be sending data to each other at 100 Mbps while two other computers are also sending at 100 Mbps. With a hub, they would each send data at around 50 Mbps. (Some switches do have a limit on the total bandwidth.)

Besides possibly being faster, switches have two other advantages. First, most 100BaseT switches can also accept 10BaseT, letting you do any mix of the two standards. Second, switches “regenerate” the signal, letting you use longer wires. As a rough rule, with hubs you should total the length of all the wires and not exceed 328 feet (100 meters), whereas with switches each wire connected to the switch can be up to 328 feet.

Years ago switches were many times more expensive than hubs. Today, they are nearly the same price. I recommend going with switches unless the budget is really tight.

Here are some sample model numbers and prices from buy.com as of 7/19/2001. Linksys: EFAH05W is a 5 port hub $40.80, EZXS55W is a 5 port switch $48.53. SMC: SMC5605DS is a 5 port hub $41.81, SMC6405TX is a 5 port switch $30.29 ($50.29 after rebate ends 7/31).

Wired connections — sharing a DSL or cable modem
If your ISP allows you to connect several computers to one modem, and doesn't charge extra or you're willing to pay the extra, then you can just connect your DSL or cable modem into your LAN the same way you'd connect a computer. (Note: some models of modems do not support multiple computers. You may need a different model if you start with one computer and then want to add more computers.) Typically your modem will have a jack wired like the jack on a hub/switch — so it can be connected directly to a NIC with a straight-through cable. Since you're using more than one computer, you're using a hub or switch (or wireless, in which case read the section above). Here's where a crossover jack on the hub or switch comes in handy — it will connect to the modem with a standard cable. If your hub/switch doesn't have a crossover jack, you'll need a crossover cable instead. (Note: as mentioned before, there are some modems that have crossover jacks rather than hub/switch-style jacks, in which case you'll use a standard cable to a regular port.)

If you want your computers to appear as a single computer to your modem, then you'll need a Broadband Router (or a Wireless Broadband Router, see the wireless section above). Linksys's Broadband Routers include BEFSR11 (with connection for 1 wired computer, which would typically go to a hub or switch), the popular BEFSR41 (includes a 4-port switch), and BEFSR81 (with 8-port switch). SMC's Broadband Routers are SMC7004ABR (includes a 4-port switch, 1 printer connection, and 1 serial-port WAN in addition to the regular WAN port) and SMC7008BR (the same, but with a 7-port switch).

These products all have a WAN jack that connects to your DSL modem or cable modem. The remaining jacks are just like the jacks on a switch. They come with complete setup instructions.

Next...
Now that you've got everything hooked up, go on to Part 2 and learn how to set up Windows. Note that to access the text of Part 2, you'll need to have your Visa, MasterCard or Discover Card handy.
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