1. Network Protocol Models and Architecture Networks and Protocols Prepared by: TGK First Prepared on: Last Modified on: Quality checked by: Copyright 2009 Asia Pacific Institute of Information Technology

2. Networks and Protocols Network Protocol Models and Architecture Slide 2 of 27 Topic & Structure of the lesson Network Standards and Protocols The ISO-OSI Model Comparing TCP/IP Architecture and the OSI Model

3. Networks and Protocols Network Protocol Models and Architecture Slide 3 of 27 Learning Outcomes At the end of this module, YOU should be able to: Explain the importance of Network standards and Protocols Explain the purpose of the OSI standards model and its contribution to network communications Explain the purpose of the TCP/IP architecture and the implementation for network communications Explain the differences between the OSI model and TCP/IP architecture

4. Networks and Protocols Network Protocol Models and Architecture Slide 4 of 27 Key Terms you must be able to use If you have mastered this topic, you should be able to use the following terms correctly in your assignments and exams: Reference model Protocol suite

5. Networks and Protocols Network Protocol Models and Architecture Slide 5 of 27 Main Teaching Points OSI Model Layering OPEN communications Communication process TCP/IP architecture Protocols

6. Networks and Protocols Network Protocol Models and Architecture Slide 6 of 27 Network Standards and Protocols Standards are important, especially to an area such as interconnectivity In data communications, the International Organization for Standards (ISO) has a proposed standard called the Open System Interconnect (OSI) Model Complexity of communication system has increased tremendously however, all networks share common functions ISO has identified and stratified these functions in the Reference Model for Open Systems Interconnection

7. Networks and Protocols Network Protocol Models and Architecture Slide 7 of 27 The Open Systems Interconnect OPEN - means any two systems conforming to the reference model and standards can communicate. i.e. different networks can interconnect The Model defines a “ Communications Architecture” using a seven (7) layer model which provides a blueprint for building a computer network Characteristics of the ‘Layer’ ConceptCharacteristics of the ‘Layer’ Concept Peer Layer Concept Entities on each layer communicate with their equivalent on the other side The ISO-OSI Model

8. Networks and Protocols Network Protocol Models and Architecture Slide 8 of 27 Service Concept Each layer uses the ‘service’ provided by the next lower layer Each layer provides ‘service’ to the next higher layer Independence Concept Each layer is independent It carries out its own task independently of other layers Implementation of each layer is independent within the standards The ISO-OSI Model

9. Networks and Protocols Network Protocol Models and Architecture Slide 9 of 27 A layer does not care or need to know how the next layer does its job The OSI layers The ISO-OSI Model Application Presentation Session Transport Network Data link Physical

10. Networks and Protocols Network Protocol Models and Architecture Slide 10 of 27 The ISO-OSI Model OSI communication process

11. Networks and Protocols Network Protocol Models and Architecture Slide 11 of 27 The ISO-OSI Model OSI layers’ headers and trailer

12. Networks and Protocols Network Protocol Models and Architecture Slide 12 of 27 The ISO-OSI Model OSI Application layer Includes functions defined by user Sometimes application programs must communicate with each other across the network Content & Format of data exchanged dictated by needs of organization Application Presentation Session Transport Network Data link Physical Data Date=mm/dd/yy

13. Networks and Protocols Network Protocol Models and Architecture Slide 13 of 27 The ISO-OSI Model OSI Presentation layer Receiving Application Has a different set of formatting rules Uses a different date format Presentation layer is responsible for translating from one format to another This can be done by changing: To a standard transmission format, which is converted by its peer layer / Directly to a format expected by receiving application

14. Networks and Protocols Network Protocol Models and Architecture Slide 14 of 27 The Presentation layer operation The ISO-OSI Model Application Presentation Session Transport Network Data link Physical Data (compressed) Date Date=dd/mm/yy

15. Networks and Protocols Network Protocol Models and Architecture Slide 15 of 27 The ISO-OSI Model OSI Session layer Establishes connection between applications Try to re-establish connection if a failure occurs Enforces rules for carrying on a dialogue between applications Rules Specify: Order in which application is allowed to communicate Pacing of information transfer so as not to overload recipient (flow control) How to bring session to an orderly conclusion

16. Networks and Protocols Network Protocol Models and Architecture Slide 16 of 27 Direction of information flow The Session layer operation The ISO-OSI Model Application Presentation Session Transport Network Data link Physical ID Length Data (compressed) connection established, Half-duplex, etc

17. Networks and Protocols Network Protocol Models and Architecture Slide 17 of 27 The ISO-OSI Model OSI Transport layer First layer concerned with world external to its processor Generates address of end user (the SENDER of data) Ensures no packets have been lost in transmission and no duplicate packets occur OSI Network layer Routes packets - is concerned with the establishing connections across network Collects billing and accounting information

18. Networks and Protocols Network Protocol Models and Architecture Slide 18 of 27 Upon receiving message from Transport Layer the Network layer:  Logs event to the accounting system  Prepares message for transmission to next node on path to destination  Looks up address of next node in Routing Table and appends address  If message is long, divides it into transmission units and appends a sequence number to each unit  Sends each unit The ISO-OSI Model

19. Networks and Protocols Network Protocol Models and Architecture Slide 19 of 27 The ISO-OSI Model The Network layer operation Application Presentation Session Transport Network Data link Physical address of next network node Routing TSAP Chksum ID Length Data Seq no Header

20. Networks and Protocols Network Protocol Models and Architecture Slide 20 of 27 OSI Data link layer Establishes and controls the physical path to next node. Tries to make the physical link reliable, in particular includes: Error detection and correction Defining beginning and end of data field Resolving competing requests for use of shared communications link OSI Physical layer Specifies electrical connections between transmission medium and computer system such as: The ISO-OSI Model

21. Networks and Protocols Network Protocol Models and Architecture Slide 21 of 27 Number of wires use to carry signals Size and shape of Connectors Speed of data transmission (BPS) Comparing the IEEE standards with the OSI Physical layer: The ISO-OSI Model OSI Physical (Layer 1) 802.3 10Base-T 802.3 10Base-T 802.3 100Base-T 802.3 100Base-T 802.3 Other Physical Layer 802.3 Other Physical Layer 802.5 Physical Layer 4 Mbps 802.5 Physical Layer 4 Mbps 802.5 Physical Layer 16 Mbps 802.5 Physical Layer 16 Mbps Other Physical Layer Other Physical Layer Multiple Physical Layer Standards Added as technology matures Added if standards creators cannot decide on one Multiple Physical Layer Standards Added as technology matures Added if standards creators cannot decide on one

22. Networks and Protocols Network Protocol Models and Architecture Slide 22 of 27 Comparing TCP/IP and OSI model

23. Networks and Protocols Network Protocol Models and Architecture Slide 23 of 27 Comparing TCP/IP and OSI model TCP/IP Chronology Late 1960s: Requirement specified by US DoD Early 1970s: ARPAnet implemented Late 1970s: Widespread use in US universities Mid 1980s: Commercial use increasing Early 1990s: HTTP became largest proportion of Internet traffic Purpose of TCP/IP Provides a common communication standard for network devices

24. Networks and Protocols Network Protocol Models and Architecture Slide 24 of 27 -`mainframes, PCs, workstations, printers, remote devices, telephones, televisions?  Provides a framework for interconnection and interoperation regardless of platform or physical network medium  Where is TCP/IP used  Basic applications: Telnet (23) –remote terminal session Comparing TCP/IP and OSI model

25. Networks and Protocols Network Protocol Models and Architecture Slide 25 of 27 FTP (21/20) –File transfer SMTP/POP (25/110) –Electronic mail NFS (Uses RPC) –Network File System More advanced applications: –HTTP (WWW port 80)  Overview The term TCP/IP is used generically to refer to anything and everything related to the specific network and transport layer protocols: Comparing TCP/IP and OSI model

26. Networks and Protocols Network Protocol Models and Architecture Slide 26 of 27  TCP  UDP  IP  ARP  TELNET  FTP Comparing TCP/IP and OSI model

27. Networks and Protocols Network Protocol Models and Architecture Slide 27 of 27 Quick Review Question 1.List the major disadvantages with the layered approach to protocols. 2.Discuss the need or lack of need for a network layer(OSI layer 3) in a broadcast network.

28. Networks and Protocols Network Protocol Models and Architecture Slide 28 of 27 Follow Up Assignment Presentation on Layered Model Approach (OSI or TCP/IP)

29. Networks and Protocols Network Protocol Models and Architecture Slide 29 of 27 Summary of Main Teaching Points

30. Networks and Protocols Network Protocol Models and Architecture Slide 30 of 27 Q & A Question and Answer Session

31. Networks and Protocols Network Protocol Models and Architecture Slide 31 of 27 Topic and Structure of next session Data Link and Flow Control Overview of Data Link Control and Flow Control Mechanisms  Flow Control Techniques  Error Detection Techniques  Error Control Techniques Next Session