Microsoft Windows XP Networking Inside Out

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broadband hardware in order to connect. Local area connections are no different—a hardware device is required. That hardware device is called a network adapter. The network adapter connects to the network using wiring or a form of wireless media; depending on your network, you might also need a device that centralizes the connections, such as a hub, a switch, or an access point (depending on the type of network you’re connecting to). The following sections introduce you to the primary hardware devices you’ll encounter when networking.

Installing a Network Adapter

A network adapter works like any other internal or external device that you might install on Windows XP. The ways in which network adapters interface with your computer depends on the type of adapter you use. Network interface cards (NICs), for instance, are typically sold as internal cards that plug into expansion slots on the computer’s motherboard. Network adapters are increasingly being integrated directly onto the motherboard in desktop and laptop computers. Many laptop computers also now come with built-in wireless LAN adapters. Network adapters are also available as

external devices that can connect to your computer’s universal serial bus (USB) port or the PC Card slots on a laptop.

Once the network adapter is installed, your computer has the capability to physically connect to the network, and the necessary networking software can be configured in Windows XP. With most types of networks, cabling is used to connect the network adapter to other computers, either directly or via a centralized hub (see “Connecting with Hubs and Switches,” opposite). Most cabled network adapters are Ethernet NICs, which you can learn more about in “Ethernet Networks,” page 60.

Network adapters are readily available at all computer stores and on the Internet. Their prices vary, but most standard internal NICs will cost you around $30 and up, as will external USB network adapters. PC Cards for laptop computers are a little pricier. Wireless adapters cost even more. You have plenty of brands to choose from, but they all perform the same function. Commonly used brands include 3Com (www.3com.com), Intel (www.intel.com), and Linksys (www.linksys.com), but you’ll find many others. Check your favorite computer store for its current offerings.

note Although it can be tempting to buy the cheapest network adapter available, it never hurts to do a little research before making the purchase. Different types of network adapters provide different features, such as hardware acceleration of some tasks (reducing the demands on the system CPU for network requests) and built-in encryption.

It’s also important to note that some companies do a far better job of updating their adapter drivers than others, and high-quality driver software is key to system stability.

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Connecting with Hubs and Switches

Most forms of wired networks utilize central concentrating devices that allow individual computers to be connected and disconnected from a network without disabling the entire network segment. The two most common forms of concentration device are hubs and switches.

A hub is a device that provides a central link to the computers on a network segment. All computers connected to a hub share the same network bandwidth, and in Ethernet networks, even compete with one another’s traffic. A switch, on the other hand, is a device that actively separates each connection so that they all have a full dedicated pipeline between any other machine on the same switch and do not compete with one another’s traffic for intercomputer communication (although the uplink connection to other networks, if present, is still shared). Switches provide higher-speed connections with greater security.

In either case—using hubs or switches—each computer connects to the device. In large office environments (as well as in some modern homes) where network connection jacks are mounted in walls (like phone jacks), the wiring is typically run to a patch bay located in a wiring closet, and each jack is patched over to a port on a hub or switch. For home and small office networks, however, external devices are almost always used.

A typical hub or switch has the requisite row of RJ-45 ports into which the RJ-45 network cables are plugged (often these are on the back of the unit along with the power cord connection, but not always). The front of the device generally has a bank of LED lights that light up or blink to show which ports are connected and to show traffic moving through the ports. On some devices, additional LEDs show other information, such as the total volume of traffic the network is handling at any given moment. Standard hubs and switches for home networks usually provide four or eight ports for connections (although some devices for large corporate networks provide up to 24 ports). Depending on the model of device you purchase, you can even link them together in a daisy chain format. You’ll need to carefully read the product’s documentation to determine if daisy chaining hubs and switches together is supported.

Some products on the market today also combine firewall capabilities and routing functions. Simple home hubs can cost as little as $50, whereas larger hubs and switches with additional features can cost upwards of $500. The transfer speed of the device also impacts the cost, which is discussed in “Choosing a Network Type,” page 55.

note Hubs are also used in wireless networks where they are called access points, but of course the access point connects to the computers wirelessly rather than with cabling. For more information about setting up a wireless network, see Chapter 19, “Wireless Networking.”

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Wiring the Network

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By definition, all nonwireless networks use some kind of wiring that connects computers to hubs or to each other. The wiring used in today’s networks is relatively standard, so you don’t have to memorize many different specifications in order to network computers. When networking computers, you will typically use one of the following cable types:

●Null modem cable. A null modem cable is used to connect two computers using their serial ports. The computers do not use a NIC, but instead send and receive data over the ports you have connected. A null modem cable connects identical pins on both attached computer ports except it crosses over the send and receive pins so communication can take place between the two machines. Null modem cables provide good temporary solutions, but they are slow.

●DirectParallel. A DirectParallel cable is a lot like a null modem cable except you use the computers’ parallel ports to connect two PCs rather than the serial ports that are used with a null modem cable. Like a null modem cable connection, a DirectParallel cable makes a good temporary networking solution, but the speed, although faster than a serial connection, is still slow.

●RJ-11 cable. RJ-11 cables are standard telephone cables. Each time you plug a phone into a wall outlet or plug a phone line into your computer’s modem, you use an RJ-11 cable. RJ-11 cables can be used in a specialized network called Home Phoneline Network Alliance (HomePNA) where the phone lines inside your home are used to network computers together instead of additional cables.

●RJ-45 cable. RJ-45 cables are by far the most common kind of network cabling in use today. They are used primarily in Ethernet networks. Category 5 cables, consisting of eight wires in four twisted pairs with RJ-45 connectors, are currently the standard for 100 megabit per second (Mbps) network cabling. You’ll find the cable in all kinds of colors and lengths at your favorite computer store, usually at an inexpensive price.

●Crossover cable. Crossover cables look like standard Category 5 cables, but the wires inside the cable are reversed (crossed over), so that signals can be exchanged between the two computers without using a hub or switch. This solution works great when you are only connecting two computers, but should you add a third computer, you’ll need a hub. Crossover cables work well for the smallest networks as well as temporary file transfer situations because, unlike null modem cables, they provide a fast network connection.

These cabling types are discussed further in relation to the types of networks they serve in “Choosing a Network Type,” page 55.

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Networking out of the Box

Because home and small office networking has become so popular these days, your computer store will likely provide complete networking kits for Ethernet, wireless, HomePNA, and possibly even Powerline networks (see the next section). These kits usually provide a few network adapter cards, wiring (if necessary), and a hub (if necessary), along with instructions and possibly even setup software to help you. In many cases, the boxed version of a network is less expensive than buying the components individually, but of course, you’ll need to be a smart shopper and compare labels to make a decision. Before you shop for networking hardware, it is a good idea to prepare a checklist of items you will need beforehand to keep you on track; otherwise,

it is easy to get distracted by the many available products and options.

Adding Routers and Residential Gateways

In addition to basic hubs and switches, you’ll find plenty of router or residential gateway devices on sale in the networking section of most computer stores. In the past, these devices were not needed for small networks, but with Internet connection sharing of Digital Subscriber Line (DSL) and cable Internet connections, these devices can be quite useful. Both can manage the connection between your network and other networks, such as the Internet, and some come with additional features that can enhance security.

A router manages traffic entering and leaving the network from the Internet or other network segments. It maintains internal tables that guide it in determining how to forward outbound traffic to remote destinations and inbound traffic to systems on the local network segment. The default gateway address configured for most TCP/IP configurations, as discussed in Chapter 2, “Configuring TCP/IP and Other Protocols,” normally points to the address of a router.

A residential gateway, on the other hand, is a router with additional features that are quite useful in most home and small office networks. Residential gateways typically combine the features of a router, a hub or switch, a firewall, a network address translation device (described below), and often a Dynamic Host Configuration Protocol (DHCP) server. Some residential gateways even have built-in wireless access points.

So how does a router or residential gateway work, and do you need one? A router or residential gateway is designed to be placed between the Internet and your LAN. The following illustration shows how the router or residential gateway provides the connection from your LAN to your DSL or cable modem.

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Internet

Connecting a LAN to the Internet Using a Residential Gateway

DSL or cable modem

	Router or residential gateway	Internet
		connection
	with integrated network hub
		LAN connections

Workstation

Workstation

Workstation

No computer is directly connected to the cable modem, and therefore no computer is directly connected to the Internet. There are two primary benefits of this kind of setup:

●No single computer acts as the gateway to the Internet. If you use Internet Connection Sharing (ICS), all Internet traffic and requests are handled by the ICS host computer (see “Using Internet Connection Sharing,” page 301, to learn more). With a router or residential gateway, the device handles all Internet requests and return traffic so that an ICS host does not have to. This eliminates the performance burden placed on the computer running ICS. Additionally, if the network computer assigned to run ICS is down, no one on the LAN can access the Internet. But with a router or residential gateway running, only the client computer accessing the Internet needs to be running. The downside of course is that a router or residential gateway costs around $100 for a basic model and more like $200–$300 for one with a firewall, remote management, and switching capabilities, whereas ICS is a free software solution included with Windows XP.

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●The more important benefit of a residential gateway is security. Most residential gateways provide security through a combination of firewalls and network address translation. Firewalls block outside networks from sending traffic to the devices they protect, limiting even response traffic to that specifically requested via outbound connections from systems behind the firewall. Many firewalls block any traffic that crosses them, other than traffic to and from specified addresses or to and from systems using virtual private network (VPN) tunnels. You can read more about firewalls in Chapter 5, “Using Internet Connection Firewall.” Network address translation (NAT) is a feature originally designed to extend IP networks that also provides a form of security by hiding the internal IP addresses of a LAN from the Internet (or other destination of the residential gateway). NAT translates the internal IP addresses of the LAN to a different IP address range. These addresses are then used for communications on the Internet. If a hacker decides to break into your network, he or she must have the real IP address of a computer on your LAN, and with NAT, those IP addresses are not visible. Therefore, any hacker attacks using IP addressing schemes simply fall apart at the residential gateway because the IP address (of the residential gateway) that allows the hacker to access your residential gateway is not the IP address that any of the machines on your LAN are using; so, the hacker is stopped at the gateway. Of course, not all routers and residential gateways provide this service, but it is common to most of them. As an example, Linksys (www.linksys.com), 3Com (www.3com.com), and NetGear (www.netgear.com) provide several different kinds of residential gateways that all perform the same tasks but provide different features. You’ll find these same features in other manufacturers’ models as well.

For more information on security, see Chapter 20, “Maintaining Network Security.”

tip Some routers and residential gateways provide DHCP services in which the router leases IP addresses to your internal network clients so that Automatic Private IP Addressing (APIPA) is not needed. This feature can provide greater client control and IP address management, especially in a growing network. For more information on DHCP, see “Dynamic and Static Addressing,” page 27.

Whether you use a router or residential gateway depends on your needs, Internet usage, and cash flow. (Keep in mind that many devices currently on the market that would meet the definition of a residential gateway are sold as routers with additional security features). However, the sheer number of attacks launched at systems connected to the Internet makes the use of a residential gateway with built-in security features a

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prudent choice, particularly if you intend to connect more than one system to the network. If you decide that a residential gateway is right for you, make sure you buy one that explicitly states that it is compatible with Windows XP. Routers and residential gateways that are compatible with Windows XP will support the Universal Plug and Play (UPnP) standard, which allows Windows XP Remote Assistance and Windows Messenger to work over the Internet without complication. Without UPnP support, you’re likely to have problems configuring these features to work properly without interference from any built-in firewalls.

tip Some routers and residential gateways can also work with additional third-party security software, such as ZoneAlarm (www.zonealarm.com). If security is a serious issue for you, be sure to do some homework before purchasing a residential gateway so that you can find the model that supports the security and software features you need. Most manufacturers’ Web sites have online documentation about their products, so you can easily study and compare products at home.

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Getting to Know NAT

NAT is a standard previously used by server software to manage network traffic between segments as well as provide security between a private network and the Internet. You can think of NAT as a translator tool that keeps the IP addresses of one LAN separate from another. In the case of Internet access, NAT can allow the router or residential gateway to act as one computer using an IP address in a different range. For example, suppose your office network has 10 computers that use a DSL modem connection, and your internal network’s IP address range is 10.0.0.1–10.0.0.10. Instead of each computer using a different IP address to access the Internet, NAT allows the router or gateway to use one IP address in a completely different class and range, such as 207.46.197.100. If an Internet hacker tries to use the 207.46.197.100 address to hack into the network, there is nothing to hack into because there is no actual computer with that IP address. Instead, the real network uses a different range and simply hides behind NAT.

In large IP networks, NAT is used to manage routing between different network segments where IP addressing between network clients and different subnets can be complicated and confusing. In many cases, NAT helps network administrators using router hardware to solve connectivity issues and problems between different network divisions. If you are interested in the technical details of NAT, you can access RFC 1631 on the Internet to learn more. A Request for Comment (RFC) is an official document of the Internet Engineering Task Force (IETF) that specifies the details of new Internet specifications or protocols. RFCs can be found on the Internet by using a Web search engine and entering the RFC number, in this case, RFC 1631.

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Choosing a Network Type

Now that you are familiar with the different types of network hardware you will typically use when networking with Windows XP, this section examines the kinds of networks that are available. So, what hardware products do you need for the kind of network you want, and what performance benefits will you get from one network type to the next? These questions can be difficult to answer, but once you have identified your networking goals and budget, you can determine the kind of network that will best suit your needs. This section explores the different types of networks you can choose when creating a home or smallto medium-size office network.

To learn more about setting up LANs, see Chapter 10, “Managing Workgroup Connections,” where you’ll also find a number of network scenarios and illustrations that explore different kinds of setups and configurations.

Direct Cable Connection (DCC)

Let’s assume that you travel with a laptop computer to a client’s site. You are not a part of the client’s network, and you don’t need to be a part of it on a permanent basis. However, you need to copy a number of files from a computer at the client site. The files are too large for floppy disks, and the client’s computer is not equipped with a Zip or Jazz drive, or a CD burner. To easily transfer the files, you can use a DCC connection. This kind of simple network connection connects two computers using a serial cable, a DirectParallel cable, a modem, or even an Integrated Services Digital Network (ISDN) device. For computers without network adapter cards or in the case of transfers from handheld devices, such as those using the Windows CE operating system, a DCC connection is a great temporary connection you can use to transfer files. You can also use a DCC connection to connect a non-networked computer to a network on a temporary basis. When connected to a computer connected to another network, you might be able to access additional network resources, depending on permissions assigned to those resources. DCC can be a lifesaver in many situations where you need quick and easy connectivity without additional hardware. However, DCC connections tend to be slow, especially null modem cable connections using a serial port. You’ll find that connection speeds are often in the modem range of approximately 24 Kbps to 50 Kbps.

DirectParallel cables that connect the parallel ports on two computers work faster, and Windows XP supports standard or basic 4-bit cables, Enhanced Capabilities Port (ECP) cables, and Universal Cable Module cables. You can purchase null modem cables at any computer store, and you can also find DirectParallel cables at www.lpt.com. Overall, the direct connection method is designed to be a quick networking fix, not a true networking solution.

You can establish a DCC connection between a Windows XP computer and any other Microsoft Windows computer that supports DCC (Windows 95, Windows 98, Windows Me, Windows 2000, or another Windows XP computer) using a null modem cable or a

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DirectParallel cable. When you create a DCC network, you must first attach the two computers together using the desired cable type. When you create a DCC network, one computer acts as the host computer, and the other computer acts as the guest. The guest computer accesses information on the host computer, but the host computer cannot access information on the guest. This solution is a great way to transfer files from one computer to another, but it is not a solution for true network communications between the two computers. Once you have the cable connected between the computers, you can set up the host computer. To set up the host computer, follow these steps:

1Log on to Windows XP with a user account that has administrative privileges. You cannot set up a DCC host unless your account has administrative privileges.

2Open Network Connections. From the Windows XP Start menu, choose Connect To, Show All Connections; from the Classic Start menu, choose Settings, Network Connections.

3In the task pane at the left under Network Tasks, select Create A New Connection. Click Next on the New Connection Wizard’s opening page.

4On the Network Connection Type page of the wizard, shown in Figure 3-1, select Set Up An Advanced Connection and click Next.

Figure 3-1. Select the Advanced Connection option to create a DCC network.

5On the Advanced Connection Options page, select Connect Directly To Another Computer and click Next.

6On the Host Or Guest page, shown in Figure 3-2, select the Host option and click Next.

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Figure 3-2. Select the Host option for the computer that will be accessed by the guest computer.

7On the Connection Device page of the wizard, select the port that you want to use for the connection, such as Infrared Port, DirectParallel, or Communications Port, from the list. The port you select is configured for DCC. You cannot use a port that currently has another device attached to it. Click Next.

8On the User Permissions page, select which users are allowed to access this host through the DCC connection. Notice that you can also create additional user accounts as needed directly from this window, as shown in Figure 3-3. Make your selections and click Next.

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Figure 3-3. Select the users who can access the host computer over the DCC connection.

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