TCP/IP allows you to communicate across networks of computers using various hardware architectures and operating systems. Microsoft's implementation of TCP/IP enables enterprise networking and connectivity between computers running Windows 2000.
After this lesson, you will be able to
Estimated lesson time: 65 minutes
Adding TCP/IP to a Windows 2000 configuration offers the following advantages:
The TCP/IP suite of protocols provides a set of standards for how computers communicate and how networks are interconnected. The TCP/IP suite of protocols maps to a four-layer conceptual model that helps to understand the tasks for which each protocol in the suite is responsible: network interface, Internet, transport, and application. These layers are illustrated in Figure 5.1.
At the base of the model is the network interface layer. This layer puts frames on the wire and pulls frames off the wire. There are no protocols in the TCP/IP suite that correspond to this layer of the model.
Figure 5.1 The TCP/IP suite of protocols within four layers
Internet layer protocols encapsulate packets into Internet datagrams and run all the necessary routing algorithms. The four Internet layer protocols are Internet Protocol (IP), Address Resolution Protocol (ARP), Internet Control Message Protocol (ICMP), and Internet Group Management Protocol (IGMP). Table 5.1 describes these four Internet layer protocols.
Table 5.1 Protocols Included in the Internet Layer
Protocol | Description |
---|---|
IP | Provides connectionless packet delivery for all other protocols in the suite. Doesn't guarantee packet arrival or correct packet sequence. |
ARP | Provides IP address mapping to the media access control (MAC) sublayer address to acquire the physical MAC control address of the destination. IP broadcasts a special ARP inquiry packet containing the IP address of the destination system. The system that owns the IP address replies by sending its physical address to the requester. The MAC sublayer communicates directly with the network adapter card and is responsible for delivering error-free data between two computers on a network. |
ICMP | Provides special communication between hosts, allowing them to share status and error information. Higher-level protocols use this information to recover from transmission problems. Network administrators use this information to detect network trouble. The ping utility uses ICMP packets to determine whether a particular IP device on a network is functional. |
IGMP | Provides multicasting, which is a limited form of broadcasting, to communicate and manage information between all member devices in a multicast group. IGMP informs neighboring multicast routers of the host group memberships present on a particular network. Windows 2000 supports multicast capabilities that allow developers to create multicast programs, such as Windows 2000 Server NetShow Services. |
Transport layer protocols provide communication sessions between computers. The desired method of data delivery determines what transport protocol will be used. The two transport layer protocols are Transmission Control Protocol (TCP) and User Datagram Protocol (UDP). Table 5.2 describes the two protocols included in the transport layer.
Table 5.2 Protocols Included in the Transport Layer
Protocol | Description |
---|---|
TCP | Provides connection-oriented, reliable communications for applications that typically transfer large amounts of data at one time or that require an acknowledgment for data received. TCP guarantees the delivery of packets, ensures proper sequencing of the data, and provides a checksum feature that validates both the packet header and its data for accuracy. |
UDP | Provides connectionless communications and doesn't guarantee that packets will be delivered. Applications that use UDP typically transfer small amounts of data at one time. Reliable delivery is the responsibility of the application. |
At the top of the model is the application layer, in which applications gain access to the network. Many standard TCP/IP utilities and services reside in the application layer. These include File Transport Protocol (FTP), Telnet, Simple Network Management Protocol (SNMP), Domain Name System (DNS), and so on.
TCP/IP provides two interfaces for network applications to use the services of the TCP/IP protocol stack: Winsock and the NetBIOS over TCP/IP (NetBT) interface. Table 5.3 describes these two interfaces.
Table 5.3 Interfaces That Applications Use for TCP/IP Services
Interface | Description |
---|---|
Winsock | Serves as the standard interface between socket-based applications and TCP/IP protocols. |
NetBT | Serves as the standard interface for NetBIOS services, including name, datagram, and session services. NetBT also provides a standard interface between NetBIOS-based applications and TCP/IP protocols. |
By default, client computers running Windows 2000, Windows 95, or Windows 98 obtain TCP/IP configuration information automatically from the Dynamic Host Configuration Protocol (DHCP) Service. However, even in a DHCP-enabled environment, you should assign a static IP address to selected network computers. For example, the computer running the DHCP Service can't be a DHCP client, so it must have a static IP address. If the DHCP Service isn't available, you must also configure TCP/IP to use a static IP address. For each network adapter card that uses TCP/IP in a computer, you can configure an IP address, subnet mask, and default gateway, as shown in Figure 5.2.
Figure 5.2 Configuring a static TCP/IP address
Table 5.4 describes options that can be used when configuring a static TCP/IP address.
Table 5.4 Options for Configuring a Static TCP/IP Address
Option | Description |
---|---|
IP address | A logical 32-bit address that identifies a TCP/IP host. Each network adapter card in a computer running TCP/IP requires a unique IP address. Each address has two parts: a network ID, which identifies all hosts on the same physical network, and a host ID, which identifies a host on the network. For the unique IP address 192.168.1.108, for example, the net- work ID is 192.168.1, and the host ID is 108. |
Subnet mask | A network in a multiple-network environment that uses IP addresses derived from a single network ID. Subnets divide a large network into multiple physical networks connected with routers. A subnet mask blocks out part of the IP address so that TCP/IP can distinguish the network ID from the host ID. When TCP/IP hosts try to communicate, the subnet mask determines whether the destination host is on a local or remote network. To communicate on a network, computers must have the same subnet mask. |
Default gateway | The intermediate device on a local network that stores network IDs of other networks in the enterprise or Internet. To communicate with a host on another network, configure an IP address for the default gateway. TCP/IP sends packets for remote networks to the default gateway (if no other route is configured), which forwards the packets to other gateways until the packet is delivered to a gateway connected to the specified destination. |
Follow these steps to configure TCP/IP to use a static IP address:
CAUTION
IP communications can fail if duplicate IP addresses exist on a network. Therefore, you should always check with the network administrator to obtain a valid static IP address.
If a server running the DHCP Service is available on the network, it can automatically assign TCP/IP configuration information to the DHCP client, as shown in Figure 5.3. You can then configure any clients running Windows 2000, Windows 95, and Windows 98 to obtain TCP/IP configuration information automatically from the DHCP Service. Using DHCP to configure TCP/IP automatically on client computers simplifies administration and ensures correct configuration information.
NOTE
Windows 2000 Professional doesn't include the DHCP Service. Only the Windows 2000 Server products provide the DHCP Service.
Figure 5.3 A server running the DHCP Service assigns TCP/IP addresses
NOTE
Windows 2000 Professional also includes an Automatic Private IP Addressing feature that provides DHCP clients with limited network functionality if a DHCP server is unavailable during startup.
You can use the DHCP Service to provide clients with TCP/IP configuration information automatically. However, you must configure a computer as a DHCP client before it can interact with the DHCP Service.
Follow these steps to configure a DHCP client:
The Windows 2000 implementation of TCP/IP supports a new mechanism for automatic address assignment of IP addresses for simple LAN-based network configurations. This addressing mechanism is an extension of dynamic IP address assignment for LAN adapters. It enables configuration of IP addresses without using static IP address assignment or installing the DHCP Service.
For the Automatic Private IP Addressing feature to function properly on a computer running Windows 2000, you must configure a network LAN adapter for TCP/IP and click Obtain An IP Address Automatically in the Internet Protocol (TCP/IP) Properties dialog box.
The process that causes Windows 2000 to utilize the Automatic Private IP Addressing feature, as shown in Figure 5.4, is explained in the following steps:
Figure 5.4 The Automatic Private IP Addressing feature
NOTE
The Internet Assigned Numbers Authority (IANA) has reserved 169.254.0.0 to 169.254.255.255 for Automatic Private IP Addressing. As a result, Automatic Private IP Addressing provides addresses that are guaranteed not to conflict with routable addresses.
After the computer generates the address, it broadcasts to this address and then assigns the address to itself, if no other computer responds. The computer continues to use this address until it detects and receives configuration information from a DHCP server. This allows two computers that are plugged into a LAN hub to restart without any IP address configuration and to use TCP/IP for local network access.
NOTE
Windows 98 also supports Automatic Private IP Addressing.
Automatic Private IP Addressing can assign a TCP/IP address to DHCP clients automatically. However, Automatic Private IP Addressing doesn't generate all the information that typically is provided by the DHCP service, such as the address of a default gateway.
Consequently, computers enabled with Automatic Private IP Addressing can communicate only with computers on the same subnet that also have addresses of the form 169.254.x.y.
By default, the Automatic Private IP Addressing feature is enabled. However, you can disable this feature by adding the IPAutoconfigurationEnabled value to the HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\Interfaces\Adapter subkey of the registry and setting its value to 0.
NOTE
This subkey includes the globally unique identifier (GUID) for the computer's LAN adapter.
The IPAutoconfigurationEnabled entry uses a REG_DWORD data type. A value of 0 disables Automatic Private IP Addressing, and the default value of 1 enables Automatic Private IP Addressing.
Windows 2000 includes several utilities that you can use to troubleshoot TCP/IP and test connectivity, which are illustrated in Figure 5.5.
Figure 5.5 TCP/IP utilities included with Windows 2000
Table 5.5 describes the Windows 2000 utilities that you can use to troubleshoot TCP/IP.
Table 5.5 Utilities Used to Troubleshoot TCP/IP
Option | Description |
---|---|
Ping | Verifies configurations and tests connections |
ARP | Displays locally resolved IP addresses as physical addresses |
Ipconfig | Displays the current TCP/IP configuration |
Nbtstat | Displays statistics and connections using NetBIOS over TCP/IP |
Netstat | Displays TCP/IP protocol statistics and connections |
Route | Displays or modifies the local routing table |
Hostname | Returns the local computer's host name for authentication by the Remote Copy Protocol (RCP), remote shell (RSH), and remote execution (REXEC) utilities |
Tracert | Checks the route to a remote system |
These troubleshooting utilities are all executed from the Command Prompt window. For information on how to use all of these commands, except Hostname and Tracert, open the Command Prompt window, type the command followed by /? and then press Enter. For example, for information on the Ping command, open the Command Prompt window, type Ping /? and then press Enter.
To use the Hostname utility, open the Command Prompt window, type Hostname and then press Enter. Hostname will return the name of the local computer.
For information on how to use the Tracert command, open a Command Prompt window, type Tracert and then press Enter.
Windows 2000 also provides utilities for testing TCP/IP connectivity. Table 5.6 describes these utilities.
Table 5.6 Utilities Used to Test TCP/IP Connectivity
Option | Description |
---|---|
FTP | Provides bidirectional file transfer between a computer running Windows 2000 and any TCP/IP host running FTP. Windows 2000 Server can serve as an FTP client or server. |
Trivial File Transfer Protocol (TFTP) | Provides bidirectional file transfer between a computer running Windows 2000 and a TCP/IP host running TFTP. |
Telnet | Provides terminal emulation to a TCP/IP host running Telnet. Windows 2000 Server can serve as a Telnet client. |
Remote Copy Protocol (RCP) | Copies files between a client and a host that support RCP, such as a computer running Windows 2000 and a UNIX host. |
Remote shell (RSH) | Runs commands on a UNIX host. |
Remote execution (REXEC) | Runs a process on a remote computer. |
Finger | Retrieves system information from a remote computer that supports TCP/IP and the finger utility. |
After configuring TCP/IP and restarting the computer, you should use the ipconfig and ping command-prompt utilities to test the configuration and connections to other TCP/IP hosts and networks. Such testing helps to ensure that TCP/IP is functioning properly.
You use the ipconfig utility to verify the TCP/IP configuration parameters on a host. This helps to determine whether the configuration is initialized, or whether a duplicate IP address exists. Use the ipconfig command with the /all switch to verify configuration information.
TIP
Type ipconfig /all | more to prevent the ipconfig output from scrolling off the screen; to scroll down and view additional output, press the Spacebar.
The result of using the ipconfig /all command is as follows:
After you have verified the TCP/IP configuration, use the ping utility to test connectivity. The ping utility is a diagnostic tool that you can use to test TCP/IP configurations and diagnose connection failures. Use the ping utility to determine whether a particular TCP/IP host is available and functional. To test connectivity, use the Ping command with the following syntax:
ping IP_address
Figure 5.6 illustrates the steps for verifying a computer's configuration and for testing router connections.
Figure 5.6 Using ipconfig and ping
The following are the steps illustrated in Figure 5.6:
NOTE
Typically, if you ping the remote host (step 5) and the ping command is successfully executed, steps 1 through 4, if ran, would also be successful by default. If the ping command isn't successfully executed, ping the IP address of another remote host before completing the entire diagnostic process because the current host might be turned off.
By default, the following message appears four times in response to a successfully executed ping command:
Reply from IP_address
In this practice, you use two TCP/IP utilities to verify your computer's configuration. You then configure your computer to use a static IP address and verify your computer's new configuration. Next you configure your computer to use a DHCP server to automatically assign an IP address to your computer, whether or not a DHCP server is available on your network. Finally you test the Automatic Private IP Addressing feature in Windows 2000 by disabling the DHCP server, if one exists on your network.
To complete this practice, you will need
If you are working on a computer that isn't part of a network and a server isn't running the DHCP service, you won't be able to do certain procedures in this practice.
In the following table, record the IP address, subnet mask, and default gateway that your network administrator provides for you to use during this practice. Also, ask your network administrator whether you can use another computer to test your computer's connectivity, and record the IP address of that computer as well. If you are not on a network, you can use the suggested values.
Variable value | Suggested value | Your value |
---|---|---|
Static IP address | 192.168.1.201 | |
Subnet mask | 255.255.255.0 | |
Default gateway (if required) | None | |
Computer to test connectivity | N/A |
In this exercise, you use two TCP/IP utilities, ipconfig and ping, to verify your computer's configuration.
NOTE
To do the exercises in this practice, you use the Command Prompt and Network Connections windows frequently. For the sake of efficiency, open the windows once and then minimize and restore them as necessary.
The Windows 2000 IP Configuration utility displays the TCP/IP configuration of the physical and logical adapters configured on your computer.
Setting | Value |
---|---|
Host name | |
Description | |
Physical address | |
DHCP enabled | |
Autoconfiguration enabled | |
IP address | |
Subnet mask | |
Default gateway | |
DNS servers |
A response similar to the following indicates a successful ping:
Pinging 127.0.0.1 with 32 bytes of data: Reply from 127.0.0.1: bytes=32 time<10ms TTL=128 Reply from 127.0.0.1: bytes=32 time<10ms TTL=128 Reply from 127.0.0.1: bytes=32 time<10ms TTL=128 Reply from 127.0.0.1: bytes=32 time<10ms TTL=128 Ping statistics for 127.0.0.1: Packets: Sent = 4, Received = 4, Lost = 0 <0% loss>, Approximate round trip times in milliseconds: Minimum = 0ms, Maximum = 0ms, Average = 0ms
In this exercise, you configure TCP/IP to use a static IP address.
To configure TCP/IP to use a static IP address
The Network And Dial-Up Connections window appears.
The Local Area Connection Properties dialog box appears, displaying the network adapter in use and the network components used in this connection.
The Internet Protocol (TCP/IP) Properties dialog box appears.
IMPORTANT
Be careful when manually entering IP configuration settings, especially numeric addresses. The most frequent cause of TCP/IP connection problems is incorrectly entered IP address information.
You are returned to the Local Area Connection Properties dialog box.
To test the static TCP/IP configuration
The Windows 2000 IP Configuration utility displays the physical and logical adapters configured on your computer.
Setting | Value |
---|---|
IP address | |
Subnet mask | |
Default gateway |
What happens?
Answer
What happens?
Answer
In this exercise, you configure TCP/IP to automatically obtain an IP address. Then you test the configuration to verify that the DHCP Service has provided the appropriate IP addressing information. Be sure to perform the first part of this exercise even if you have no DHCP Service server because you will also use these settings in Exercise 4.
To configure TCP/IP to automatically obtain an IP address
The Local Area Connection dialog box appears.
The Internet Protocol (TCP/IP) Properties dialog box appears.
Which IP address settings will the DHCP Service configure for your computer?
Answer
To test the TCP/IP configuration
NOTE
If a server running the DHCP Service isn't available to provide an IP address, skip this procedure and proceed to Exercise 4.
Setting | Value |
---|---|
IP address | |
Subnet mask | |
Default gateway |
The internal loopback test displays four replies if TCP/IP is bound to the adapter.
For this exercise, if you have a server running the DHCP Service, you must disable it on that server so that a DHCP server will not be available to provide an IP address for your computer. Without a DHCP server available to provide an IP address, the Windows 2000 Automatic Private IP Addressing feature provides unique IP addresses for your computer. If the DHCP Service can't be disabled, simply disconnect your network adapter cable.
To obtain an IP address by using Automatic Private IP Addressing
There will be a pause while Windows 2000 attempts to locate a DHCP server on the network.
What message appears, and what does it indicate?
Answer
To test the TCP/IP configuration
Setting | Value |
---|---|
IP address | |
Subnet mask | |
Default gateway |
Is this the same IP address that was assigned to your computer in Exercise 3? Why or why not?
Answer
The internal loopback test displays four replies if TCP/IP is bound to the adapter.
Were you successful? Why or why not?
Answer
In this exercise, you enable the DHCP Service running on the computer that is acting as a DHCP server (or you reconnect your network cable if you disconnected it in Exercise 4). Your computer will obtain IP addressing information from the DHCP server.
NOTE
If a server running the DHCP Service isn't available to provide an IP address, skip this exercise.
After a short wait, a message indicates the adapter's local area connection.
In this lesson, you learned that TCP/IP enables enterprise networking and connectivity on computers running Windows 2000. It provides a robust, scalable, cross-platform client/server framework that is supported by most large networks, including the Internet. You learned that the TCP/IP suite of protocols maps to a four-layer conceptual model: network interface, Internet, transport, and application.
By default, client computers running Windows 2000 obtain TCP/IP configuration information automatically from the DHCP Service. However, even in a DHCP-enabled environment, some computers, such as the computer running the DHCP Service, require a static IP address. For each network adapter card that uses TCP/IP in a computer, you can configure an IP address, a subnet mask, and a default gateway.
You also learned that Windows 2000 includes utilities that you can use to troubleshoot TCP/IP and test connectivity. Ping and ipconfig are two common troubleshooting utilities, and FTP and telnet are two connectivity utilities.
Finally, in this lesson you learned that the Windows 2000 implementation of TCP/IP supports automatic private IP addressing. Automatic private IP addressing is a new mechanism for automatic address assignment of IP addresses for simple LAN-based network configurations. It is an extension of dynamic IP address assignment for LAN adapters and enables configuration of IP addresses without using static IP address assignments or installing the DHCP Service. By default, the Automatic Private IP Addressing feature is enabled. However, you can disable this feature by adding IPAutoconfigurationEnabled to the registry.