1. Copyright © Genetic Computer School 2008 Computer Systems Architecture SA 12- 0 Lesson 12 The TCP/IP Protocol Suite

2. Copyright © Genetic Computer School 2008 Computer Systems Architecture SA 12- 1 LESSON OVERVIEW  The OSI model  The OSI layers  The TCP/IP protocol stack  TCP/CP application

3. Copyright © Genetic Computer School 2008 Computer Systems Architecture SA 12- 2 OSI Model_1 The Open Systems Interconnection (OSI) reference model is a framework for defining standards for linking heterogeneous computers. The OSI model provides the basis for connecting "open" systems for distributed applications processing.

4. Copyright © Genetic Computer School 2008 Computer Systems Architecture SA 12- 3 OSI Model_2 The term "open" denotes the ability of any two systems conforming to the reference model and the associated standards to connect. A widely accepted structuring technique, and the one chosen by ISO, is layering. The communication functions are partitioned into a vertical set of layers. Each layer performs a related subset of the functions required to communicate with another system.

5. Copyright © Genetic Computer School 2008 Computer Systems Architecture SA 12- 4 OSI Model_3 It relies on the next lower layer to perform more primitive functions and to conceal the details of those functions. It provides services to the next higher layer. Ideally, the layers should be defined so that changes in one layer do not require changes in the other layers.

6. Copyright © Genetic Computer School 2008 Computer Systems Architecture SA 12- 5 OSI Layers  Physical  Data Link  Network  Transport  Session  Presentation  Application

7. Copyright © Genetic Computer School 2008 Computer Systems Architecture SA 12- 6 Perspectives On ]The OSI Architecture

8. Copyright © Genetic Computer School 2008 Computer Systems Architecture SA 12- 7 Layers of TCP/IP Protocol Suite

9. Copyright © Genetic Computer School 2008 Computer Systems Architecture SA 12- 8 Link Layer The first, the link layer, is responsible for communicating with the actual network hardware (e.g., the Ethernet card).

10. Copyright © Genetic Computer School 2008 Computer Systems Architecture SA 12- 9 Network Layer The second, the network layer, is responsible for figuring out how to get data to its destination. Making no guarantee about whether data will reach its destination, it just decides where the data should be sent.

11. Copyright © Genetic Computer School 2008 Computer Systems Architecture SA 12- 10 Transport Layer The third, the transport layer, provides data flows for the application layer. It is at the transport layer where guarantees of reliability may be made.

12. Copyright © Genetic Computer School 2008 Computer Systems Architecture SA 12- 11 Application Layer The fourth, the application layer, is where users typically interact with the network. This is where telnet, ftp, email, IRC, etc. reside.

13. Copyright © Genetic Computer School 2008 Computer Systems Architecture SA 12- 12 A Sample Ethernet Frame

14. Copyright © Genetic Computer School 2008 Computer Systems Architecture SA 12- 13 TCP/IP Application  SMTP  FTP  TELNET

15. Copyright © Genetic Computer School 2008 Computer Systems Architecture SA 12- 14 SMTP The simple mail transfer protocol (SMTP) provides a basic electronic mail facility. It provides a mechanism for transferring messages among separate hosts. Features of SMTP include mailing lists, return receipts, and forwarding.

16. Copyright © Genetic Computer School 2008 Computer Systems Architecture SA 12- 15 FTP The file transfer protocol (FTP) is used to send files from one system to another under user command. Both text and binary files are accommodated, and the protocol provides the features for controlling user access.

17. Copyright © Genetic Computer School 2008 Computer Systems Architecture SA 12- 16 TELNET_1 TELNET provides a remote logon capability, which enables a user at a terminal or personal computer to logon to a remote computer and function as if directly connected to that computer. The protocol was designed to work with simple scroll-mode terminals.

18. Copyright © Genetic Computer School 2008 Computer Systems Architecture SA 12- 17 TELNET_2 TELNET is actually implemented in two modules:  User TELNET  Server TELNET