1. 1. Introduction and Background Network Performance and Quality of Service

2. Things you need to know … Instructor:  Dr. Rehan Qureshi Reference Books:  High-speed Networks and Internets- W. Stallings  High Performance TCP/IP Networking- Hassan,Jain Email:  riqureshi@gmail.com, rqureshi@iqra.edu.pk RQ20122

3. What is … ? Communication  Information transfer, according to agreed conventions using hand signals, language, Morse code, smoke signals etc. Telecommunication  Communication at a distance, includes telephony, telegraphy, television etc. Data Communication  Transfer of data from one or more sources to one or more destinations. Computer Network  A network of data processing nodes that are interconnected for the purpose of data communication. RQ20123

4. Components of data communication system Message, Sender, Receiver, Medium, Protocol RQ20124 A set of rules that governs data communication The physical path by which a message travels The data (information) to be communicated

5. Data communication system Its effectiveness depends upon three characteristics …  Delivery To deliver data to correct destination  Accuracy To deliver data accurately  Timeliness To deliver data in a timely manner RQ20125

6. Direction of data flow Simplex Half-duplex Full-duplex RQ20126

7. What is a network? It is a set of devices (nodes) connected by communication links. A node can be a computer or printer etc. RQ20127

8. Why make a network? Because of networks we can …  Share resources ( Peripherals, files, internet connection etc.)  Communicate and collaborate  Save data RQ20128

9. Network criteria Three most important criteria for evaluating a network are …  Performance  Reliability  Security RQ20129

10. Types of Connection Point-to-point Multipoint RQ201210

11. Point-to-point connection Provides a dedicated link between devices. Entire capacity of the link is reserved for the two devices. RQ201211

12. Multipoint connection More than two specific devices share a single link. The capacity of the channel is shared. RQ201212

13. Categories of networks A Network is categorized with respect to its size, its ownership, the distance it covers and its physical architecture. RQ201213

14. What is a protocol? It is a set of rules that governs data communication RQ201214

15. Standardized Protocol Architectures Required for devices to communicate Vendors have more marketable products Customers can insist on standards based equipment Two standards:  OSI Reference model Never lived up to early promises  TCP/IP protocol suite Most widely used Also: IBM Systems Network Architecture (SNA) RQ201215

16. The OSI Model International Standards Organization (ISO)  An organization dedicated to worldwide agreement on international standards. Open Systems Interconnection (OSI)  An ISO standard/model that covers all aspects of network communications. RQ201216

17. OSI Model All People Seems To Need Data Processing RQ201217

18. The OSI model RQ201218

19. OSI vs. TCP/IP RQ201219

20. Internet (TCP/IP) Model RQ201220

21. Protocol Hierarchies The entities comprising the corresponding layers on different machines are called peers. RQ201221

22. Protocol Hierarchies RQ201222 Layer 5 (Application)

23. Protocol Hierarchies RQ201223

24. Protocol Hierarchies RQ201224 PDU Fragmentation Assembly

25. Internet Layers RQ201225

26. Physical Layer It is responsible for transmitting individual bits from one node to the next. It is mainly concerned with …  Characteristics of transmission medium  Signal levels  Data rates RQ201226

27. Data Link Layer It is responsible for transmitting frames from one node to the next. Its major duties are …  Framing  Physical Addressing  Flow Control  Error Control  Access Control RQ201227

28. Node to node delivery A node with physical address 10 sends a frame to a node with physical address 87. The two nodes are connected by a link. At the data link level this frame contains physical addresses in the header. These are the only addresses needed. The rest of the header contains other information needed at this level. The trailer usually contains extra bits needed for error detection RQ201228

29. Node to node delivery RQ201229

30. Network Layer Responsible for the delivery of packets from the original source to the final destination. Performs routing functions across multiple networks Implemented in end systems and routers RQ201230

31. Source to destination delivery RQ201231

32. Source to destination delivery RQ201232

33. Transport Layer It is responsible for delivery of a message from one process to another. Its major functions are …  Port Addressing  Connection Control  Flow Control  Error Control RQ201233

34. Process to process delivery RQ201234

35. Process to process delivery RQ201235

36. Application Layer It is responsible for providing services to the user. RQ201236

37. Summary RQ201237