Lesson 1: Understanding the TCP/IP Protocol Suite

Lesson 1:?Understanding the TCP/IP Protocol Suite

TCP/IP provides communication across networks of computers with various hardware architectures and operating systems. Microsoft's implementation of TCP/IP enables enterprise networking and connectivity on computers running Windows XP Professional.


After this lesson, you will be able to

  • Describe the TCP/IP protocol suite and the TCP/IP tools that ship with Windows XP Professional

Estimated lesson time: 25 minutes


The TCP/IP Protocol Suite

TCP/IP is an industry-standard suite of protocols that enables enterprise networking and connectivity on Windows XP Professional-based computers. Adding TCP/IP to a Windows XP Professional configuration offers the following advantages:

  • A routable networking protocol supported by most operating systems. Most large networks rely on TCP/IP.
  • A technology for connecting dissimilar systems. You can use many standard connectivity tools to access and transfer data across dissimilar systems. Windows XP Professional includes several of these standard tools.
  • A robust, scalable, cross-platform client/server framework. TCP/IP supports the Microsoft Windows Sockets (Winsock) interface, which is ideal for developing client/server applications for Winsock-compliant stacks.
  • A method of gaining access to Internet resources.

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: network interface, Internet, transport, and application. These layers can be seen in Figure 4.1.

Figure 4.1??The TCP/IP suite of protocols within four layers

Network Interface Layer

At the base of the model is the network interface layer, which puts frames on the wire and pulls frames off the wire.

Internet Layer

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 4.1 describes these four Internet layer protocols.

Table 4.1??Protocols Included in the Internet Layer

Transport Layer

Transport layer protocols provide communication sessions between computers. The desired method of data delivery determines the transport protocol. The two transport layer protocols, described in Table 4.2, are Transmission Control Protocol (TCP) and User Datagram Protocol (UDP).

Table 4.2??Protocols Included in the Transport Layer

Protocol Description

TCP

Provides connection-oriented, reliable communications for applications that typically transfer large amounts of data at once or require an acknowledgment for data received. TCP is connection-oriented, so a connection must be established before hosts can exchange data. TCP provides reliable communication by assigning a sequence number to each segment of data that is transmitted so that the receiving host can send an acknowledgment (ACK) to verify that the data was received. If an ACK is not received, the data is retransmitted. 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 but does not guarantee the delivery or the correct sequence of packets. Applications that use UDP typically transfer small amounts of data at once. Reliable delivery is the responsibility of the application.

Application Layer

At the top of the model is the application layer, in which applications gain access to the network. There are many standard TCP/IP tools and services in the application layer, such as File Transfer 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 4.3 describes these two interfaces.

Table 4.3??Interfaces Through Which Applications Use TCP/IP Services

Lesson Review

Here are some questions to help you determine whether you have learned enough to move on to the next lesson. If you have difficulty answering these questions, review the material in this lesson before beginning the next lesson. The answers are in Appendix A, "Questions and Answers."

  1. What are the four layers to which the TCP/IP suite of protocols maps? What are the functions of the protocols that map to each layer?
  2. Which of the following statements correctly describes IP? (Choose all answers that are correct.)
    1. IP guarantees packet arrival and correct packet sequence.
    2. IP provides connection-oriented, reliable communications for applications that typically transfer large amounts of data at one time.
    3. IP is primarily responsible for addressing and routing packets between hosts.
    4. IP provides connectionless packet delivery for all other protocols in the suite.
  3. Which of the following statements correctly describes TCP? (Choose all answers that are correct.)
    1. TCP provides connectionless communications but does not guarantee that packets will be delivered.
    2. TCP provides connection-oriented, reliable communications for applications that typically transfer large amounts of data at one time.
    3. TCP provides services that allow the application to bind to a particular port and IP address on a host.
    4. TCP provides and assigns a sequence number to each segment of data that is transmitted.
  4. Which of the four layers to which the TCP/IP suite of protocols maps does IGMP map to and what is IGMP used for?
  5. What is multicasting?
  6. The two transport layer protocols are ____________________________ and _______________________________________.
  7. Which of the following statements correctly describes ARP? (Choose all answers that are correct.)
    1. ARP is a protocol included in the Internet layer.
    2. ARP is a protocol included in the transport layer.
    3. ARP provides IP address mapping to the MAC sublayer address to acquire the physical MAC control address of the destination.
    4. ARP is primarily responsible for addressing and routing packets between hosts.

Lesson Summary

  • Microsoft's implementation of TCP/IP provides a robust, scalable, cross-platform client/server framework that is supported by most large networks, including the Internet.
  • Windows XP Professional includes many standard connectivity tools to access and transfer data between dissimilar systems.
  • The TCP/IP suite of protocols maps to a four-layer conceptual model: network interface, Internet, transport, and application.
  • The four Internet layer protocols-IP, ARP, ICMP, and IGMP-encapsulate packets into Internet datagrams and run all the necessary routing algorithms.
  • IP provides connectionless, unreliable packet delivery for all other protocols in the TCP/IP suite and is primarily responsible for addressing and routing packets between hosts.
  • The two transport layer protocols-TCP and UDP-provide communication sessions between computers.
  • TCP provides connection-oriented, reliable communications for applications that typically transfer large amounts of data at once or require an acknowledgment for data received.
  • There are many standard TCP/IP tools and services in the application layer, such as FTP, Telnet, SNMP, 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 NetBT interface.