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Figure 2-3. The Advanced TCP/IP Settings dialog box enables you to manually configure IP and related settings.

The IP Settings tab shows the configured IP addresses. If static IP addresses are being used, this location allows multiple IP addresses to be bound to a single network interface. This is primarily useful in the case of systems being used for tasks such as production Web servers and is not commonly needed for Windows XP Professional or Windows XP Home Edition. If you are using DHCP, this box will show the message “DHCP Enabled” instead of a list of IP addresses. The Default Gateways section of the dialog box enables you to define one or more default gateways. By assigning different interface metrics (at the bottom of the dialog box), you can specify the order in which these gateways are used. If the Automatic Metric check box is selected, the best gateway will be determined dynamically.

tip The Automatic Metric setting is typically best when multiple IP gateways are available.

The DNS tab allows the specification of multiple DNS servers, as shown in Figure 2-4. The up arrow and down arrow buttons next to the text boxes allow you to configure the order in which the DNS servers are queried when name resolution is needed. The options in the lower portion of the dialog box allow you to specify which DNS suffix is appended to DNS requests for system names that are not FQDNs; for example, a user might want to substitute the shorter mycomputer for the full FQDN mycomputer.microsoft.com. Normally, such a substitution will result in a name resolution failure, but Windows XP will attempt to append each DNS suffix to a name resolution request and retry that request before finally returning an error to the client

software. Staying with the example, if you add microsoft.com to the list of DNS suffixes, Windows XP will automatically attempt to resolve mycomputer.microsoft.com once the resolution request for mycomputer fails.

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Figure 2-4. You can configure specific DNS servers on the DNS tab.

The next tab in the Advanced TCP/IP Settings dialog box is the WINS tab, which is shown in Figure 2-5 on the next page. This tab lets you configure the servers and settings used for WINS-based name registration and resolution. Aside from specifying the address of servers and the order in which to use them, there are two other key settings. The Enable LMHOSTS Lookup option determines what the computer will do if all other attempts to resolve the NetBIOS name fail. If selected, the computer will check a local file known as the LMHOSTS file. This file is sometimes used to create custom NetBIOS computer name-to-IP mappings. If LMHOSTS files are in use on a network and there is a centralized store for the custom LMHOSTS file, clicking the Import LMHOSTS button allows you to import the file. The NetBIOS Setting section determines whether or not NetBIOS over TCP/IP (NetBT) and WINS are used. The default setting is usually best. In pure Active Directory networks, WINS is not required.

For more information on WINS, see “Windows Internet Naming Service (WINS)” on page 27.

The Options tab displays the single entry, TCP/IP Filtering. When you select this option and click Properties, the TCP/IP Filtering dialog box opens, as shown in Figure 2-6 on the next page. If you select Enable TCP/IP Filtering (All Adapters), you can then specify allowed and blocked TCP and UDP ports as well as which IP protocols are permitted for traffic destined for this computer. This is a security feature that allows you to block IP protocols and TCP or UDP ports that should not be used on the network. By filtering traffic that you don’t need for communication, you also block the possibility of malicious users using those ports as access points to your computer.

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Figure 2-5. Use the WINS tab to configure WINS settings.

caution Make sure you do not block any traffic ports unless you have a specific security reason for doing so. Blocking traffic limits the functionality of TCP/IP and what you will be able to do on your network. If security is a major concern, you can block any traffic that you know will not be used, but keep in mind that greater restrictions might cause you to lose some network functionality.

Figure 2-6. You can specify IP protocols and TCP or UDP ports that you want to allow or block using IP filtering.

For more details on using filtering to enhance security under Windows XP, see Chapter 20, “Maintaining Network Security.”

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Understanding Internet

Protocol Version 6 (IPv6)

When TCP/IP was first developed, the Internet Protocol version 4 (IPv4) addressing scheme seemed so large that it could never run out of IP addresses. However, with the hundreds of millions of hosts on the Internet today, the limits of IPv4’s address space is being felt. With IPv4, there is considerable concern about the possibility of IP address exhaustion despite attempts to work around the problem with techniques such as NAT and subnetting. In anticipation of this, the successor to IPv4 has been designed by the Internet Engineering Task Force (IETF). The new standard, IPv6, will utilize a much larger addressing space (128 bits instead of IPv4’s 32 bits), allowing a multitude of new addresses. Additionally, IPv6 is designed from the ground up to provide easier configuration and better built-in security.

note IPv6 provides so many potential IP addresses that every man, woman, and child on Earth could maintain their own dedicated range of IP addresses, and that range could be as large as the entire address space available for the Internet under IPv4!

Because any new IP addressing scheme will eventually affect every computer on the Internet, the details must be well established and migration paths must be clearly defined. It would not be feasible to suddenly switch addressing schemes and have millions of hosts unable to communicate with each other. IPv6 is currently undergoing testing, and some Web sites are not supporting the standard. Eventually, however, the Internet’s entire IP infrastructure will migrate to IPv6.

IPv6 is provided in Windows XP mainly for software developers. You can install IPv6 and use it for testing and application development purposes. However, it should be noted that technical support for IPv6 as a production protocol is not provided, so you’ll have to experiment with it at your own risk.

Using IPv6 with Windows XP

Chapter 2

The following steps will help you install the developer preview IPv6 protocol stack on your computer. Once installed, the IPv6 protocol stack will not appear in the Properties dialog box for any network interface. Not many Web sites or networks currently support IPv6 connections, but the number is growing rapidly. To install IPv6 on Windows XP, follow these steps:

1Log on to the computer using an account with administrative privileges.

2From the Start menu click Run.

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3Type cmd in the text box that appears.

4In the window that opens, type the command ipv6 install and press Enter. If the installation succeeds, you’ll see the message “Succeeded.”

5To reverse the process, repeat steps 1–4 but type the command ipv6 uninstall instead. Uninstalling will take a few more seconds and will require that you restart the machine.

Once the IPv6 protocol stack is installed on a Windows XP computer, it is possible to attach that computer to the publicly accessible IPv6 backbone. For details about connecting to this developmental IPv6 backbone, visit www.6bone.com. For additional information about the use of IPv6 and Windows XP as well as the available IPv6 tools, be sure to check the Microsoft Web site link that provides IPv6 information at www.microsoft.com/ipv6.

Other Networking Protocols

Although the TCP/IP protocol suite is by far the most ubiquitous networking protocol suite, there are other network protocols. The remainder of this chapter examines protocols that come into play when working in a mixed operating system environment.

Keep in mind that if you are on a pure Windows network, you do not need to use any other protocols besides TCP/IP. In fact, you might even be working in a mixed network that only uses TCP/IP because many other operating systems also take advantage of all that TCP/IP has to offer.

This chapter explores the protocol side of mixed networks. However, you can learn more about Windows XP’s interoperability with other networks in Chapter 18, “Interconnectivity with Other Systems.”

Internetwork Packet Exchange (IPX)

The IPX protocol was developed by Novell, Inc. for its NetWare family of operating systems. At one point in the past, NetWare was the most widely distributed server platform in use. NetWare’s market share has somewhat diminished since then, but it is still possible that Windows and NetWare might be required to coexist for some time. With newer versions of NetWare, the support for TCP/IP has greatly improved. Regardless, it is still very likely that if NetWare is present, support for IPX will be useful if not required.

IPX Addressing

IPX, like IP, requires that all hosts have unique addresses. IPX addresses are 80 bits in length and include a network portion and a node portion. In addition to a node and network portion, there is a component known as the socket number. All IPX addresses

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are stored in a hexadecimal format. The following is a description of the key IPX network addressing components:

●Network number. The first 32 bits of any IPX address is the network portion of the address and is assigned manually by an administrator. Typically, this simple number is 0001 or 1000. Because IPX does not transport over the Internet (which uses IP), there is no need for complex unique addresses. A site with six IPX segments could use (in binary form) 0001, 0002, and 0003 to 0006 to separate the six networks.

●Host number. The remaining 48 bits are (in most cases) the MAC address of the NIC participating in the IPX network. Some MAC addresses are programmable, so this portion of the address is also potentially manageable. But in most cases, the host number is a fixed value.

●Socket number. The socket number identifies a process running on an IPX node and is analogous to a TCP or UDP port. It is used to determine what application the incoming or outgoing traffic should be routed to.

●Service Advertising Protocol (SAP). SAP is a broadcast protocol used to advertise the set of service names and addresses across the IPX network and to resolve service names to the IPX network and node addresses. Each server advertises the services offered using a numeric type, name, and network address. IPX routers accumulate this information to use in IPX routing activities.

Implementing IPX with Windows XP

You can install the IPX protocol on Windows XP so that Windows XP can function in an IPX network. The following steps are required to install support for the IPX environment under Windows XP:

1From the Start menu, open Network Connections.

2Locate the connection to the network. It will probably be labeled with the default name, Local Area Connection.

3Right-click the Local Area Connection icon, and choose Properties from the shortcut menu.

4On the General tab, click the Install button.

5In the Select Network Component Type dialog box, select Client, and click Add.

6Select Client Service For NetWare, as shown in Figure 2-7 on the next page, and click OK. This will install the NetWare client components as well as Microsoft’s NWLink IPX/SPX/NetBIOS protocol.

After a few moments, the client and IPX/SPX protocol stack will be installed and will appear in the Local Area Connection Properties dialog box.

Chapter 2

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note Some NetWare environments might require the use of Novell’s own NetWare client and IPX protocol software. Contact your network administrator to determine if this is the case before attempting to use the Microsoft implementation of IPX.

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Figure 2-7. Choose the protocol you want to install.

AppleTalk

Created by Apple for Macintosh computers, AppleTalk was originally designed to support small workgroups, but was later revised to support larger, more complex networks. On an AppleTalk network, addressing is divided into four components: zones, networks, nodes, and sockets. All addresses are assigned dynamically on an AppleTalk network. When a node joins the network, it selects an address and sends out a broadcast to determine whether anyone replies at that address. If another node replies, the newly joined node chooses another address. This process repeats until the new node obtains an available network address. A brief explanation of the four components in AppleTalk addressing follows:

●Zones. A zone is a collection of individual nodes or networks. Zone membership is a user-configured characteristic. Nodes and networks need not be connected to the same network segment to share zone membership.

●Networks. A collection of nodes connected to the same switch, bridge, or router is considered a member of the same network. This is equivalent to a physical network segment. There are two types of AppleTalk networks: extended and nonextended. Extended networks can use what Apple refers to as a cable range to assign multiple network numbers to a single physical segment. This is conceptually similar to an IP virtual LAN (VLAN). Nonextended networks are physical segments that all share the same network number.

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Managing Broadcast Protocols

in Mixed OS Environments

Many network protocols make extensive use of broadcasts to maintain consistent communications across the network. Although this is rarely an issue on smaller networks, as networks begin to scale upward, broadcasting can result in out-of-control traffic that can be crippling. The biggest offenders when it comes to generating broadcast traffic include SAP and AppleTalk.

To prevent broadcast traffic from consuming an inordinate amount of the bandwidth available on the network, routing must be used. Routers can be configured to block broadcasts. This ability to segregate broadcast traffic allows a broadcast-dependent protocol such as SAP to operate on one portion of the network without negatively impacting the rest of the network.

●Nodes. The AppleTalk term node has the same meaning as the generic terms node, host, client, and so forth. Any device connected to the network that is capable of participating in networked communications is a node.

●Sockets. Sockets are the equivalent of the TCP or UDP port number. Sockets identify applications that are sending and receiving data.

Implementing AppleTalk with Windows XP

Chapter 2

Although Windows XP can communicate with AppleTalk-enabled computers, the communication is indirect. Windows XP does not come with a user installable AppleTalk protocol suite. Earlier versions of Windows did support various forms of the AppleTalk protocol suite, but Windows XP does not. Server versions of Windows 2000, however, continue to offer support for AppleTalk clients, and Windows XP Professional users can access an AppleTalk network when a server version of Windows 2000 acts as an intermediary. Only then can you access files and printing services in the AppleTalk environment from Windows XP.

The lack of support for AppleTalk is not likely to be of significant concern for very long. Newer Apple operating systems, such as Mac OS X, include robust support for TCP/IP, so interconnectivity between those systems is much easier.

note Both NetWare and Mac OS systems have moved away from proprietary protocols and support TCP/IP as their standard protocol suite (much as Microsoft moved away from NetBIOS to use only TCP/IP in pure Active Directory environments). However, an understanding of these legacy protocols is still important because their use is still widespread.

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Avoiding Spanning Tree

Protocol Communication Problems

One of the more insidious problems that can occur on a mixed operating system network is incompatibilities with protocols used by networking devices. These incompatibilities often manifest themselves sporadically and can be extremely hard to track down. One very real concern with AppleTalk-enabled hosts is a known defect that causes AppleTalk communications to occasionally fail when the Spanning Tree Protocol (STP) is in use. STP is used on a wide range of network devices to provide redundancy. For example, a pair of network switches can have two links connecting each other together, so that if either link fails, communication can still occur. To prevent communication loops (which can disable the whole network), STP is used to make one of the links inactive, but kept on standby. STP is active by default on a great number of network devices. When it is active, computers using the AppleTalk protocol are likely to experience serious communications problems. The solution is to either move to another network protocol (such as IP) or to disable STP.

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Chapter 3

Understanding
Network Hardware	47
Components
Choosing a	55
Network Type
Installing NICs	68
Managing
Network	69
Connections

1: Windows XP Networking

Creating Network

Connections

To create any kind of network connection, you must have two components—hardware that allows your computer to connect to the physical network and software that allows your computer to communicate on the network. Microsoft Windows XP includes the software you need to create network connections, but you must determine what hardware you need and install it before you can set up the networking software. Your computer might have preconfigured networking hardware, but there are a number of different network solutions that you can employ, and you should understand them all before you make a final decision on which to employ.

In this chapter, network hardware, types of networks, and connections will be explored, with an emphasis on networking your local Windows XP computer.

Understanding Network

Hardware Components

Network hardware enables a computer to connect to other computers, either directly or via a shared network medium. Without networking hardware, each computer lives on its own island, so to speak. Even if you are simply accessing the Internet, your computer must have either a dial-up modem or some kind of

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