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Chapter Overview

TCP/IP Overview Configuring TCP/IP Clients Using TCP/IP Utilities

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TCP/IP Overview

Transmission Control Protocol/Internet Protocol (TCP/IP) is an industry-standard suite of protocols used on local area networks (LANs) and wide area networks (WANs).

Microsoft Windows 2000 supports TCP/IP.

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Architectural Overview of the TCP/IP Protocol Suite

The TCP/IP protocols Provide networking connectivity support for

computers (called hosts) on LANs and WANs Follow a set of standards for how computers

communicate and how networks are interconnected

Follow the four-layer Department of Defense (DOD) model

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The Four-Layer TCP/IP Model

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Application Layer Software programs gain access to the

network through the application layer. This layer maps roughly to the session,

presentation, and application layers of the Open Systems Interconnection (OSI) model.

The following TCP/IP utilities and services run at the application layer: Hypertext Transfer Protocol (HTTP) File Transfer Protocol (FTP) Simple Mail Transfer Protocol (SMTP)

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Application Layer (Cont.)

TCP/IP utilities and services that run at the application layer (Cont.): Telnet Domain Name System (DNS) Simple Network Management Protocol (SNMP)

Microsoft TCP/IP provides two interfaces for applications to use: WinSock Network Basic Input/Output System (NetBIOS)

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Transport Layer Transport protocols

Provide communication sessions between computers

Define the type of transport service as either connection-oriented or connectionless datagram-oriented

This layer maps roughly to the transport layer in the OSI model.

The transport layer protocols are TCP: connection-oriented, reliable UDP: connectionless, no guarantee of packet

delivery

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Internet Layer The Internet layer protocols encapsulate

transport layer data into units called datagrams, address them, and route them to their destinations.

This layer maps roughly to the network layer in the OSI model.

Windows 2000 implements three main protocols at this layer: Internet Protocol (IP) Address Resolution Protocol (ARP) Internet Control Message Protocol (ICMP)

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Link Layer This layer sends and receives frames,

which are packets of information transmitted on a network as a single unit.

The link layer is equivalent to the data-link and physical layers of the OSI model.

Two protocols often used for WAN connections are part of the TCP/IP suite: Point-to-Point Protocol (PPP) Serial Line Internet Protocol (SLIP)

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Transmission Control Protocol Transmission Control Protocol (TCP) is a

reliable, connection-oriented delivery service. TCP achieves reliability by using a system

called positive acknowledgment with retransmission.

Many Internet client applications, such as Web browsers and FTP clients, rely on TCP to transmit files.

Virtually every application that transmits large amounts of data over a network uses TCP.

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User Datagram Protocol (UDP) Provides a connectionless datagram service

that does not guarantee delivery or correct sequencing of delivered packets

Used by applications that Do not require an acknowledgment of data receipt Usually transmit small amounts of data at one time

Used by Broadcast transmissions Services and applications such as DNS, Dynamic

Host Configuration Protocol (DHCP), and SNMP

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Internet Protocol

Internet Protocol (IP) does the actual delivery of datagrams.

IP adds the following header fields to each packet: Source IP Address Destination IP

Address Protocol

Checksum Time to Live (TTL)

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IP Addressing Every host on a TCP/IP network must have a

unique IP address (a 32-bit number that identifies both the host and the network the host is located on).

IP addresses are expressed in dotted-decimal format, such as 192.168.123.132.

Each set of four dotted-decimal numbers represents eight bits of the binary address. The addresses range from 00000000 to

11111111, or, in decimal notation, from 0 to 255.

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IP Addressing (Cont.) An IP address is accompanied by a subnet mask. The subnet mask, when compared to the IP

address, identifies the part of the IP address that is the network identifier and the part that is the host identifier.

The 1s identify network bits and the 0s identify host bits.

In the subnet mask 255.255.0.0, the first 16 bits (2 octets) are the equivalent of all ones in binary form.

The first two octets of the IP address are the network identifier. The last two octets represent the host identifier.

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Understanding IP Address Classes To communicate on the Internet, a computer must

use an IP address that is registered with the Internet Assigned Numbers Authority (IANA).

In practice, you obtain a valid network address from your Internet service provider (ISP), not directly from the IANA.

The IANA assigns network identifiers only; the administrator assigns a unique host identifier to each computer.

There are three primary classes of network addresses: A, B, and C.

The actual class used is based on the size of the network. Each address class has a different default subnet mask.

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IP Address Classes

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IP Address Class Characteristics

You can identify the class of an IP address by looking at the value of its first octet.

Because a Class A address uses only eight bits for its network ID, only 126 possible Class A addresses exist.

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General Guidelines for IP Address Assignments There are several general guidelines for how to

assign IP addresses: The first octet of the network ID cannot be 127. The network and host ID bits cannot be all 1s. The network and host ID bits cannot be all 0s. The host ID for each computer must be unique. A unique network ID is required for each network

and wide area connection. A registered network ID is required for connecting to

the Internet. All TCP/IP hosts require unique host IDs. Each host requires a subnet mask.

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Using Private Addresses

Workstations protected by firewalls and computers that do not connect to the Internet can use unregistered, private IP addresses.

When building a private network, you should use one of the special ranges of private IP addresses, rather than assigning IP addresses randomly.

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IP Address Ranges for Private Networks

Class Network Addresses

A 10.0.0.0 through 10.255.255.255

B 172.16.0.0 through 172.31.255.255

C 192.168.0.0 through 192.168.255.255

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Understanding IP Routing Routing is the process of choosing a

path over which to send packets, which is the primary function of IP.

A router (also called a gateway) is a device that forwards packets from one physical network to another.

Routers match packet headers to a LAN segment and choose the best path for the packet, which optimizes network performance.

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Packet Routing Example

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IP Routing To make routing decisions, the IP layer

consults a routing table, which consists of a series of entries, called routes.

On a computer running Windows 2000, a routing table is built automatically based on its TCP/IP configuration.

To view a routing table on a computer running Windows 2000, at a command prompt, type route print, and then press Enter.

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Static and Dynamic IP Routing Static routing can only use fixed routing

tables. Static routers require building and updating

routing tables manually. Use the Route.exe command to add static

entries to the routing table. Dynamic routing

Automatically updates routing tables Uses routing protocols, such as Routing Information

Protocol (RIP) and Open Shortest Path First (OSPF), to periodically transmit the contents of their routing tables to the other routers on the network

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Lesson Summary TCP/IP follows the four-layer DOD model:

application, transport, Internet, and link. IP is the primary protocol of the Internet layer. TCP is a connection-oriented protocol that

provides reliable delivery for applications that generate large amounts of data.

UDP is a connectionless protocol used to transmit small amounts of data without packet acknowledgment.

Every computer on a TCP/IP network must have a unique IP address, consisting of a network ID and a host ID.

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Installing TCP/IP The Windows 2000 setup program

automatically installs TCP/IP if it detects a network interface adapter in the computer.

You need to manually install TCP/IP on a computer running Windows 2000 only if

The default protocol selection was overridden during setup

You have deleted it from a connection In Windows 2000, TCP/IP is implemented as a

single module called Internet Protocol (TCP/IP), which is installed from the Network And Dial-Up Connections application in Control Panel.

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Installing TCP/IP (Cont.)

To manually install TCP/IP:1. Log on using an administrator account.2. Click Start, point to Settings, and then click Network And Dial-Up Connections. 3. Right-click the Local Area Connection icon, and then select Properties to display the Local

Area Connection Properties dialog box.

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Installing TCP/IP (Cont.)

To manually install TCP/IP (Cont.): 4. Click Install. 5. In the Select Network Component Type

dialog box, select Protocol, and then click Add.

6. In the Select Network Protocol dialog box, select Internet Protocol (TCP/IP) in the Network Protocol list, and then click OK. (You might need to supply Windows 2000 installation files.)

7. Click Close.

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The Local Area Connection Properties Dialog Box

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Configuring TCP/IP Create a detailed plan for using IP

addressing on your network. You might be able to use private IP

addresses for most of your computers, but connecting to the Internet requires a registered IP address.

You can configure Windows 2000 TCP/IP clients to Assign IP addresses dynamically by using DHCP Use Automatic Private IP Addressing Configure TCP/IP manually

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Configuring TCP/IP with DHCP By default, computers running Windows

2000 try to obtain TCP/IP configuration parameters from a DHCP server on the network.

If a computer running Windows 2000 currently has a static TCP/IP configuration, you can change it to obtain its IP address automatically by selecting Obtain An IP Address Automatically in the Internet Protocol (TCP/IP) Properties dialog box of a connection.

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Configuring Your Computer to Obtain TCP/IP Settings Automatically

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Configuring TCP/IP Manually Some servers, such as DHCP, DNS,

Windows Internet Name Service (WINS), Internet Web, and FTP servers, should be assigned an IP address manually.

If you do not have a DHCP server on your network, you must manually configure computers to use a static IP address.

To manually configure a computer to use a static IP address, configure TCP/IP in the Internet Protocol (TCP/IP) Properties dialog box of a connection.

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Assigning Special Permissions for an Active Directory Object You can also configure a Microsoft TCP/IP

client with additional IP addresses, subnet masks, and default gateways.

To configure additional IP addresses, subnet masks, and default gateways:

1. In the Internet Protocol (TCP/IP) Properties dialog box for a connection, click

Advanced.2. Configure settings in the Advanced TCP/IP

Settings dialog box.

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The Advanced TCP/IP Settings Dialog Box

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Using Automatic Private IP Address Assignment By default, if a computer running

Windows 2000 that is configured to use DHCP cannot obtain an IP address from a DHCP server, Windows 2000 uses Automatic Private IP Addressing to assign itself an IP address. The addresses range from 169.254.0.1

through 169.254.255.254. The computer uses this IP address until it

successfully contacts a DHCP server, from which it receives a new IP address.

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Testing TCP/IP with Ipconfig and Ping You should always test and verify your TCP/IP

configuration. Use Ipconfig to view the TCP/IP configuration

settings on a host, including IP address, subnet mask, and default gateway.

At a command prompt, type ipconfig and then press Enter.

Use Ping to test connectivity. Ping uses Echo Request messages to determine whether

a specified TCP/IP host is available and functioning. At a command prompt, type ping target (where target

is the IP address or name of the target computer) and then press Enter.

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Lesson Summary Windows 2000 installs TCP/IP by default if it detects

a network interface adapter in the computer. You can manually install TCP/IP in the Network And

Dial-up Connections application. To configure TCP/IP manually, use the Internet

Protocol (TCP/IP) Properties dialog box of a connection.

By default, computers running Windows 2000 try to obtain their IP addresses automatically by using DHCP.

If a DHCP server is not available, Automatic Private IP Addressing assigns an IP address to the computer.

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Using TCP/IP Utilities

TCP/IP includes an assortment of utilities that gather information about various protocols and the network.

TCP/IP utilities are usually command-line utilities.

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Using Ping Ping is a command-line utility that uses Echo

Request messages to determine if the TCP/IP stack of another computer on the network is functioning normally.

From a command prompt, type ping target (where target is the IP address or the name [DNS or NetBIOS] of the computer you are trying to contact). A successful ping results in several reply

messages from the target computer. If the ping fails, one or both computers might

have a networking hardware or software problem.

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Using Traceroute

Tracert.exe, a variant of Ping, displays the path that packets take to their destination.

From a command prompt, type tracert target (where target is the IP address or the name [DNS or NetBIOS] of the target computer).

Use Tracert.exe to isolate the location of a network communications problem, particularly when a router is suspected.

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Using Pathping Pathping is a route tracing tool that

Sends packets to each router on the way to a final destination over a period of time

Computes results based on the packets returned from each hop

You can use Pathping.exe to isolate problems because it shows the degree of packet loss at any given router or link.

From the command line, type pathping target (where target is the IP address or the name [DNS or NetBIOS] of the target computer).

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Using Ipconfig.exe Use Ipconfig.exe to view the TCP/IP

configuration settings on a host, including IP address, subnet mask, and default gateway. At the command prompt, type ipconfig or

ipconfig /all and then press Enter. Use the /all parameter to display more

information. Running Ipconfig is an easy way to view the

IP address and other parameters that the DHCP server has assigned to your computer.

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Using Route.exe

Use Route.exe to create, delete, or modify static routes in a routing table on a computer running Windows 2000.

Route.exe uses the following syntax:ROUTE [-f] [-p][command[destination] [MASK netmask] [gateway] [METRIC metric] [IF interface]]

The Route.exe command variable takes one of four values:

PRINT ADD

DELETE CHANGE

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Using Route.exe (Cont.) The ROUTE PRINT command displays the

current contents of the routing table. To delete an entry, use ROUTE DELETE

with a destination variable. To create a new entry, use ROUTE ADD

with parameters that specify the values for the entry.

To modify an entry, use ROUTE CHANGE with the appropriate destination variable.

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Adding a Static Route by Using Route.exe

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Using Arp.exe

IP uses ARP to discover the hardware address that each datagram is transmitted to.

Resolved addresses are stored in an ARP cache.

Use Arp.exe to view or change the contents of the ARP cache.

Arp.exe uses the following syntax: ARP [-a {ipaddress}] [-n ipaddress] [-s ipaddress hwaddress {interface}] [-d ipaddress {interface}]

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Using Netstat.exe

Netstat.exe is a Windows 2000 command-line utility that displays information about The current network connections of a

computer using TCP/IP The traffic generated by various TCP/IP

protocols Netstat.exe uses the following syntax: NETSTAT [interval] [-a] [-p protocol] [-n] [-e] [-r] [-s]

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Using Nbtstat.exe Nbtstat.exe is a Windows 2000 command-

line utility that displays information about the NetBIOS over TCP/IP connections used by Windows 2000 when communicating with other Windows computers on a TCP/IP LAN.

Nbtstat.exe uses the following syntax:NBTSTAT [-a name] [-A ipaddress] [-c] [-n] [-r] [-R] [-s] [-S] [-RR]

The parameters for Nbtstat.exe are case-sensitive.

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Using Nslookup.exe Nslookup.exe is a Windows 2000 command-

line utility that enables you to generate DNS request messages and transmit them to a specific DNS server on the network.

Nslookup.exe uses the following syntax: NSLOOKUP DNSname DNSserver

DNSname specifies the DNS name you want to resolve.

DNSserver specifies the DNS name (or IP address of the DNS server) you want to query for the name you want to resolve.

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Using Netdiag.exe The Netdiag command-line utility helps

isolate networking and connectivity problems by performing a series of tests on a computer.

Netdiag.exe checks all aspects of a computer's network configuration and connections, including TCP/IP, Internet Packet Exchange (IPX), and NetWare configurations.

Run Netdiag whenever a computer is having network problems.

At a command prompt, type netdiag and then press Enter.

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Lesson Summary Use Ping to determine if the TCP/IP stack of

another computer on the network is functioning normally.

Tracert.exe displays the path that packets take to their destination.

Pathping is a route tracing tool that Sends packets to each router on the way to a final

destination over a period of time Computes results based on the packets returned from

each hop Use Ipconfig.exe to view the TCP/IP configuration

settings on a host, including IP address, subnet mask, and default gateway.