How Home Networking Works


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How Home Networking Works

  1. 1. How Home Networking Works If you are one these multiple-PC owners, you have probably thought about how great it would be if your computers could talk to each other. With your computers connected, you could: • Share a single printer between computers • Use a single Internet connection • Share files such as images, spreadsheets and documents • Play games that allow multiple users at different computers • Send the output of a device like a DVD player or Webcam to your other computer(s) In this article, we'll look at all of the different methods you can use to create a home network. Ways to Connect You can connect your home computers in a variety of ways: • Wire your house with data cables • Run cables across the floor between computers in the same room • Install some form of wireless networking (see How Wireless Networking Works for details) • Link your computers through your power lines (see How Power-line Networking Works for details) • Link your computers through your phone lines (see How Phone-line Networking Works for details) • Walk diskettes back and forth (which is inexpensive but gets to be a drag) Each of these methods has advantages and disadvantages, and in this article we'll discuss them in detail. But all of these methods (except physically carrying diskettes) require you to configure your computers to share printers, files and an Internet connection and to set up some level of security. This configuration process is common to any form of networking, so that's where we'll start. Once we establish a basic understanding of the configuration process, we'll discuss phone- line networking, power-line networking, Ethernet networking and wireless networking in detail. By the time you finish this series, you'll be able to choose the network technology that suits your needs and configure the whole thing! Networking Basics To install a network in your home, there are three steps: 1. Choose the technology you will use for the network. The main technologies to choose between are standard Ethernet, phone-line-based, power-line-based and wireless. There are other technologies that exist, such as Token Ring and FDDI, but they are not recommended for use in a home network unless you already have extensive experience with that particular technology. 2. Buy and install the hardware. 3. Configure the system and get everything talking together correctly.
  2. 2. Step 3 is extremely important. It is also very educational -- if you understand the configuration process, you understand everything a home network is capable of doing for you. Some of the home-networking kits include an installation CD that makes configuration very easy. The program will take you through each step of naming the computer, sharing files, sharing printers and sharing an Internet connection. But if you have problems, or if your kit does not include a configuration program, you'll need to know how to set it up manually. To assist you with setting up your network, we'll discuss the following tasks, which apply no matter which networking technology you choose: • Naming the PC • Sharing files / printers • Security • Sharing an Internet connection Once you understand these tasks, you'll understand just what your new network can do! Naming the PC Before your computer can become part of a network, it has to have a name and a workgroup. Each computer in your home network needs to have a different name, and they all need to be in the same workgroup. Networking Basics: File Sharing and Security One of the most common activities on any computer network is "file sharing." Sharing your entire hard drive is not recommended. It is too easy for someone to accidentally delete an important system file if the whole disk is shared. Instead, create folders that will be used specifically to share files. You may want one folder for the entire family and another one limited to you and your spouse. Restricting access to certain files is crucial for most businesses and can certainly be important to you at home. For example, you may have documents that you would not want your children to be able to see or change. Or perhaps you have important financial information that you wish to keep private. Whatever the reason, it is useful to be able to restrict access to information on each computer through the use of share-level password protection. Networking Basics: Internet Microsoft implemented Internet Connection Sharing. ICS lets you connect one computer to the Internet by whatever means (modem, DSL, ISDN or cable) and share that connection with any other Windows computer on the network. Though simple in theory, the actual implementation of ICS proved problematic for many users. While file and printer sharing are still relatively easy, Internet-connection sharing using only software is a good deal trickier. In most cases, you will need to configure a router or gateway that will bridge between the Internet and your home network.
  3. 3. Networking Basics: Routers and Firewalls Much of the work required to get information from one computer to another is done by routers -- they're the crucial devices that let information flow between, rather than within, networks. Routers are specialized computers that send your messages, and those of every other Internet user, speeding to their destinations along thousands of pathways. When information needs to travel between networks, routers determine how to get it there. A router has two separate but related jobs: • It ensures that information doesn't go where it's not needed. This is crucial for keeping large volumes of data from clogging the connections of "innocent bystanders." • It makes sure that information makes it to the intended destination(s). In performing these two jobs, a router is extremely useful in dealing with two separate computer networks. It joins the two networks, your home network and the Internet in this case, passing information from one to the other. It also protects the networks from one another, preventing the traffic on one from unnecessarily spilling over to the other. Regardless of how many networks are attached, the basic operation and function of the router remains the same. Whether you are one of the growing number of computer users with fast, always-on Internet access or you're still using a dial-up connection, you may want to consider implementing a firewall. A firewall is simply a program or hardware device that filters the information coming through the Internet connection into your private network or computer system. You use a firewall to protect your home network and family from offensive Web sites and potential hackers. If an incoming packet of information is flagged by the filters, it is not allowed through. You should note that some spam is going to get through your firewall as long as you accept e-mail. And, while some firewalls offer virus protection, it is worth the investment to install anti-virus software on each computer. The level of security you establish will determine how many threats can be stopped by your firewall. You can restrict traffic that travels through the firewall so that only certain types of information, such as e-
  4. 4. mail, can get through. The highest level of security would be to simply block everything. Obviously, that defeats the purpose of having an Internet connection. But a common rule of thumb is to start out blocking everything, and then begin to select what types of traffic you will allow. This is a good rule for businesses that have an experienced network administrator who understands what the needs are and knows exactly what traffic to allow through. For most of us, it is probably better to work with the defaults provided by the firewall developer unless there is a specific reason to change them. Hardware firewalls are incredibly secure and not very expensive. One of the best things about a firewall from a security standpoint is that it stops anyone on the outside from logging onto a computer in your private network. While this is a big deal for businesses, most home networks will probably not be threatened in this manner. Still, putting a firewall in place provides some peace of mind. For more information on firewalls, see How Firewalls Work. Building a Network You've learned how to make your computer recognize other computers in its network and begin sharing printers, files and an Internet connection. We'll now look closely at four types of home computer networks -- how each works, what each costs and what the pros and cons are. The options we will discuss are: • Ethernet networking • Phone-line networking • Power-line networking • Wireless networking Ethernet Networking Ethernet is easily the most popular networking system available today. It is also one of the widest ranging systems. The equipment needed for an Ethernet-based network can be as simple as two network interface cards (NIC) and a cable, or as complex as multiple routers, bridges and hubs. It is this versatility that makes it so useful to businesses. We will focus on the basics for creating a home network. Pros and Cons
  5. 5. Ethernet has many advantages: • It is the fastest home-networking technology (100 Mbps). • It can be inexpensive if the computers are close to one another. • It is extremely reliable. • It is easy to maintain after it is set up. • The number of devices that can be connected is virtually unlimited. • There is a great deal of technical support and information available. And a few disadvantages: • If you have more than two computers, you'll need additional equipment. • It can be expensive if wiring and jacks need to be installed. • Set-up and configuration can be difficult. • The technical jargon and the number of options can be confusing. Go on to the next page for complete information on this networking technology. What You Need for Ethernet Ethernet is available in three speeds: 10 Mbps,100 Mbps and 1 Gbps. Most NICs are capable of operating at these speeds, but you should check to be sure before purchasing. There are two different ways to connect Ethernet cards: coax and Cat 5 cabling. Coax was once the more popular of the two, but today just about everyone uses Cat 5 because it is easier to configure. Cat 5 has a cable that looks a lot like a telephone cable. You run one cable to each computer, and each cable connects to a hub at the other end. To connect more than two computers using Ethernet, you will need a hub like this. The hub takes the signal from each computer and sends it to all of the other computers in your home. Hubs come in several sizes, noted by the number of ports available -- a four-port hub can connect four computers, an 8-port hub can connect up to eight computers and so on. Most hubs are stackable. A stackable hub has a special port that can connect it to another hub to increase the capacity of your network. So if you start with a four-port hub but eventually have five computers, you can buy another four-port hub and connect it to the one you already have, increasing the potential number of computers on your network. A cable/DSL router usually
  6. 6. has a four-port Ethernet hub built in. To connect the computers, you will need Unshielded Twisted Pair (UTP) Category 5 cable. This type of cabling is designed to handle the 100-Mbps speed needed by Ethernet. The RJ-45 connector at the end of the cable looks very similar to the RJ-11 connector on a phone cord but is slightly bigger (and not compatible). You can buy Cat 5 cables in predetermined lengths with the connectors already attached. If you plan to install the Cat 5 cabling in the walls of your house, you can buy the cable in rolls, cut it to length and connect the cable to special RJ-45 wall boxes. Unless you have done this type of installation before, you will probably want to hire a professional. *Note: If you want to connect just two computers, you can avoid the hub and use a crossover Cat 5 cable. With a crossover cable, you directly connect one NIC card to the other without a hub. This only works for two computers -- to connect more than two you need a hub. How Wireless Networking Works Wireless networking is one of several ways to connect the computers in your home. It creates a network by sending radio-frequency signals between your computers to share information. In this article, we'll talk about wireless networking and the technology used to make it happen. We'll also discuss the advantages and disadvantages of using a wireless network. Wireless Networking Wireless networking technologies take the concept of "no new wires" one step further. In a wireless network, all of the computers in your home broadcast their information to one another using radio signals. This can make networking extremely easy, especially if you have computers all over your house. It also makes it a whole lot simpler to move computers around. For example, a laptop with a wireless network card is completely portable throughout the house! There are four types of wireless networks, ranging from slow and inexpensive to fast and expensive: • Bluetooth • IrDA • HomeRF (SWAP) • WECA (Wi-Fi) Bluetooth is not expected to replace the need for high-speed data networks between computers. You can read more about this cutting-edge technology in How Bluetooth Short Range Radio Systems Works. IrDA (Infrared Data Association) is a standard for devices to communicate using infrared light pulses. This is how remote controls operate, and the fact that all remotes use this standard allows a remote from one manufacturer to control a device from another manufacturer. Since IrDA devices use infrared light, they depend on being in direct line of sight with each other.
  7. 7. Although you can purchase and install an IrDA-based network capable of transmitting data at speeds up to 4 megabits per second (Mbps), the requirement for line of sight means that you would need an access point in each room, limiting the usefulness of an IrDA network in a typical home layout. Before we talk about SWAP and Wi-Fi, we need to understand the original standard that both of these new specifications are based on. The original Institute of Electrical and Electronics Engineers wireless-Ethernet specification, known as IEEE 802.11, designated two ways of communicating between devices and allowed for speeds up to 2 Mbps. Both communication methods, direct-sequence spread spectrum (DSSS) and frequency-hopping spread spectrum (FHSS), use the frequency-shift keying (FSK) technology we discussed in power- line networking. Also, both are based on spread-spectrum radio waves in the 2.4-gigahertz (GHz) range. Spread spectrum simply means that data is sent in small pieces over a number of the discrete frequencies available for use at any time in the specified range. Devices using direct-sequence spread spectrum (DSSS) communicate by splitting each byte of data into several parts and sending them concurrently on different frequencies. DSSS uses a lot of the available bandwidth, about 22 megahertz (MHz). Devices using frequency-hopping spread spectrum (FHSS) send a short burst of data, shift frequencies (hop) and then send another short burst. Since the FHSS devices that are communicating agree on which frequencies to hop to, and use each frequency for a brief period of time (less than 400 milliseconds) before moving on, several independent FHSS networks can exist in the same physical area without interfering with each other. Also, due to FCC restrictions, as well as the fact that FHSS devices generally send data on just two to four frequencies simultaneously, they only use 1 MHz or less of the available bandwidth. Because they use any given frequency for such a short time, FHSS devices are less prone to interference than DSSS devices. But DSSS is capable of much greater speed than FHSS since these devices can send a lot more data at the same time. Currently, FHSS-based devices are easier and cheaper to produce, which has led the HomeRF group to adopt FHSS as the method of communication for their products. HomeRF and SWAP The HomeRF Working Group (RF stands for radio frequency) was an alliance of businesses that developed a standard called Shared Wireless Access Protocol (SWAP). A sort of hybrid standard, SWAP includes six voice channels based on the Digital Enhanced Cordless Telecommunications (DECT) standard and the 802.11 wireless-Ethernet specification for data. SWAP devices make 50 hops per second and transmit at 1 Mbps. Depending on the manufacturer, some of these can step up to 2 Mbps if there is very little interference in their operational area. Here are the advantages of SWAP: • It's inexpensive • It's easy to install. • It requires no additional wires. • It has no access point. • It uses six full-duplex voice channels and one data channel. • It allows up to 127 devices per network.
  8. 8. • It allows multiple networks in the same location. • You can use encryption to make your data secure. Here are the disadvantages of SWAP: • It's not very fast (normally 1 Mbps). • It has a limited range (75 to 125 ft / 23 to 38 m). • It's not compatible with FHSS devices. • Physical obstructions (walls, large metal objects) can interfere with communication. • It's difficult to integrate into existing wired networks. This wireless PCI card is inserted inside your computer to build a wireless network. The actual wireless transceiver, with a small, integrated antenna, is built into an ISA, PCI or PCMCIA card. If you have a laptop computer, the PCMCIA card plugs directly into one of the PCMCIA slots. For desktop computers, you will either need a dedicated ISA or PCI HomeRF card, or a PCMCIA card with a special adapter. ISA and PCI adapters are inserted inside the computer and have a slot that is accessible from the back of your computer so you can plug in the PCMCIA card. USB adapters are external devices that you plug the PCMCIA card into and then connect to a USB port on the computer. Some of the HomeRF manufacturers sell kits that include the appropriate adapter along with the PCMCIA cards and installation software. Currently, because of the need to use dedicated cards, only computers can participate in a SWAP network. Printers and other peripheral devices need to be physically connected to a computer and shared as a resource by that computer. In most cases, SWAP-based networks are point-to-point. Some manufacturers do offer access points as an option to increase the effective range of the wireless network, but they are not required equipment. Mainly because of this lack of an access point, HomeRF networks are significantly cheaper than the other viable wireless network, WECA's Wi-Fi. But the tradeoffs for cost are speed and distance. If you can set up a wired network using HomePNA or traditional Ethernet, you will get 10 to 100 times the speed for the same amount of money or less. However, unless you plan to send large amounts of data (like video) back and forth, SWAP speed is probably adequate for most home use, and the freedom of no wires can be quite appealing. Just remember that this is still a developing technology. WECA and Wi-Fi The Wireless Ethernet Compatibility Alliance (WECA) has gone in a completely different direction from HomeRF. Targeted more at office use than home networks (although
  9. 9. increasingly used within the home), Wi-Fi (for "wireless fidelity", like Hi-Fi for "high fidelity" in audio equipment) is essentially a seal of approval that says the manufacturer's product is compliant with a variation of the IEEE 802.11 specification known as IEEE 802.11b. This specification drops FHSS and focuses on DSSS because of the higher data rate it can attain. Under 802.11b, devices communicate at a speed of 11 Mbps whenever possible. If signal strength or interference is disrupting data, the devices will drop back to 5.5 Mbps, then 2 Mbps and finally down to 1 Mbps. Though it may occasionally slow down, this keeps the network stable and very reliable. Photo courtesy Nexland The ISB Wavebase by Nexland allows you to connect wireless devices to your fast Internet connection. Here are the advantages of Wi-Fi: • It's fast (11 Mbps). 802.11g • It's reliable. The newest update to the 802.11 • It has a long range (1,000 ft / 305 m in open areas, standard, 802.11g, features 250 to 400 ft / 76 to 122 m in closed areas) major speed gains. 802.11g • It's easily integrated into existing wired-Ethernet offers up to 54 Mbps, as opposed networks. to 11 Mbps for 801.11b. See • It's compatible with original 802.11 DSSS devices. IEEE: Popular Wireless Local Area Networks Gain Large Boost in Speed to learn more. Here are the disadvantages: • It's expensive. • It can be difficult to set up. • Speed can fluctuate significantly. Wi-Fi offers Ethernet speeds without the wires, but you pay for it. There are Wi-Fi compatible PC cards that operate in peer-to-peer mode, but Wi-Fi usually requires access points. Most access points have an integrated Ethernet controller to connect to an existing wired-Ethernet network. It also has an omni-directional antenna to receive the data transmitted by the wireless transceivers.