Learning objectives of this chapter include: Understand the architecture of the OSI model, understand the layers of the OSI model and their functions, understand the architecture of the TCP/IP Protocol Suite, differentiate between the OSI model and the TCP/IP Suite, differentiate between the three types of Internet addresses. | Chapter 2 The OSI Model and TCP/IP Protocol Suite CONTENTS THE OSI MODEL LAYERS IN THE OSI MODEL TCP/IP PROTOCOL SUITE ADDRESSING TCP/IP VERSIONS THE OSI MODEL ISO is the organization. OSI is the model. Figure 2-1 OSI Model Figure 2-2 OSI layers Headers are added to the data at layers 6, 5, 4, 3, and 2. Trailers are usually added only at layer 2. Figure 2-3 An exchange using the OSI model LAYERS IN THE OSI MODEL Figure 2-4 Physical Layer Figure 2-5 Data Link Layer Figure 2-6 Node-to-node delivery Figure 2-7 Network Layer Figure 2-8 End-to-end delivery Figure 2-9 Transport Layer Figure 2-10 Reliable end-to-end delivery of a message Figure 2-11 Session Layer Figure 2-12 Presentation Layer Figure 2-13 Application Layer Figure 2-14 Summary of layers TCP/IP PROTOCOL SUITE Figure 2-15 TCP/IP and OSI model ADDRESSING Figure 2-16 Addresses in TCP/IP Figure 2-17 Relation- ship of layers and addresses in TCP/IP Example 1 Figure shows an example of physical addresses. Figure 2-18 Physical addresses Example 2 Most local area networks use a 48-bit (6 bytes) physical address written as 12 hexadecimal digits, with every 2 bytes separated by a hyphen as shown below: 07-01-02-01-2C-4B A 6-byte (12 hexadecimal digits) physical address Example 3 Figure shows an example of Internet addresses. Figure 2-19 IP addresses Example 4 As we will see in Chapter 4, an Internet address (in IPv4) is 32 bits in length, normally written as four decimal numbers, with each number representing 1 byte. The numbers are separated by a dot. Below is an example of such an address. Example 5 Figure shows an example of transport layer communication. Figure 2-20 Port addresses Example 6 As we will see in Chapters 11 and 12, a port address is a 16-bit address represented by one decimal number as shown below. 753 A 16-bit port address TCP/IP VERSIONS Versions: Version 4 (current) Version 5 Version 6 (future) | Chapter 2 The OSI Model and TCP/IP Protocol Suite CONTENTS THE OSI MODEL LAYERS IN THE OSI MODEL TCP/IP PROTOCOL SUITE ADDRESSING TCP/IP VERSIONS THE OSI MODEL ISO is the organization. OSI is the model. Figure 2-1 OSI Model Figure 2-2 OSI layers Headers are added to the data at layers 6, 5, 4, 3, and 2. Trailers are usually added only at layer 2. Figure 2-3 An exchange using the OSI model LAYERS IN THE OSI MODEL Figure 2-4 Physical Layer Figure 2-5 Data Link Layer Figure 2-6 Node-to-node delivery Figure 2-7 Network Layer Figure 2-8 End-to-end delivery Figure 2-9 Transport Layer Figure 2-10 Reliable end-to-end delivery of a message Figure 2-11 Session Layer Figure 2-12 Presentation Layer Figure 2-13 Application Layer Figure 2-14 Summary of layers TCP/IP PROTOCOL SUITE Figure 2-15 TCP/IP and OSI model ADDRESSING Figure 2-16 Addresses in TCP/IP Figure 2-17 Relation- ship of layers and addresses in TCP/IP Example 1 Figure shows an example of physical addresses.
