Networks and Protocols

1. Networks and Protocols - What is really going on when we send emails and surf the web? Networks and Protocols - Introduction

2. The Book: Computer Networking A Top-Down Approach Featuring the Internet, by James F. Kurose og Keith W. Ross, Addison-Wesley Longman, Inc., se http://www.awl.com/kurose-ross/ Kan købes på IT-Højskolen d. 6. – 7. Feb 2002 i lokale 1.05 fra 11.00 til 15.00. Pris: Kr. 645,- Networks and Protocols - Introduction

3. Excercises and Instructors Rooms: 3.15 and 3.16, Glentevej 67. Monday Afternoon (13:00 – 15:30): Anders Ejlev, (anders@ejlev.dk) Monday Evening (19:00 – 21:30): Sune Kloppenborg Jeppesen, (jaervosz@it-c.dk) Networks and Protocols - Introduction

4. Examination – June 2002 20 min individual oral examn without preparation, judged using the, Dansih 13-scale, external censor. It is allowed to bring a disposition (one sheet of A4 paper for each question) The book will be available at the exam. Networks and Protocols - Introduction

5. Outline feb 4. 2002 • What is the internet? • What is a Protocol? • Connection-Oriented service. • Connectionless service. • Multiplexing. • Message switching (demo). • Packet switching (demo). • Routing. • Access Networks. • Delay and Packet loss i a network. • Protocol Layering. • Course overview. Networks and Protocols - Introduction

6. Some Internet Applications • Email • Streaming multimedia • www • File transfer • Internet telephony Networks and Protocols - Introduction

7. Some pieces of the Internet Networks and Protocols - Introduction

8. A service description • The Internet: • Allows distributed applications running on it’s end systems to exchange data with each other. • Provides a connection-oriented and a connectionless service. • Makes no promises about time of delivery. Networks and Protocols - Introduction

9. What is a protocol? A human protocol and a computer network protocol. Networks and Protocols - Introduction

10. Definition (protocol): A protocol defines the format and the order of messages exchanged between two or more communicating entities, as well as the actions taken on the transmission and/or receipt of a message or other event. Networks and Protocols - Introduction

11. End systems, Clients and Servers Networks and Protocols - Introduction

12. Connection-Oriented Service • Initial handshake. • Reliable data transfer, using acknowledgements. • Flow Control. • Congestion Control. Note: The Transmission Control Protocol (TCP) implements a connection-oriented service. Used by: Email, www, FTP, Telnet. Networks and Protocols - Introduction

13. Connectionless Service • No Initial handshake. • Unreliable data transfer. • No Flow Control. • No Congestion Control. Note: The User Datagram Protocol (UDP) implements a connectionless service. Used by: audio on demand, intertenet telephony, … Networks and Protocols - Introduction

14. The Network Core Networks and Protocols - Introduction

15. How to share a communication link? • In Curcuit switching (e.g. ordinary telephone) a curcuit is reserved for the duration of the session. • In Packet switching (e.g. internet) the ressource is used on demand. Note: Sharing is called Multiplexing. Networks and Protocols - Introduction

16. Multiplexing (FDM) Frequency-division multiplexing (FDM): Each Connection gets 4 KHz of the total frequency spectrum. Networks and Protocols - Introduction

17. Multiplexing (TDM) Frame Time-division Multiplexing: Each connection get one slot in each Frame. Networks and Protocols - Introduction

18. Multiplexing for Packetswitching. Networks and Protocols - Introduction

19. Message Switching Networks and Protocols - Introduction

20. Packet switching Networks and Protocols - Introduction

21. Example: Message Switching Networks and Protocols - Introduction

22. Example: Packet Switching Networks and Protocols - Introduction

23. Demo: Packet Switching Run the JAVA Applet on: http://www.awl.com/kurose-ross/ Networks and Protocols - Introduction

24. Break • Table Tennis • Table soccer Networks and Protocols - Introduction

25. Routing: Virtual Curcuit Networks VC number translation table for PS1: Networks and Protocols - Introduction

26. Routing: Datagram Networks Using: Hierarchical adresse, e.g: Tom Jones (name) Walnut Street 421 (street) Philadelphia (city) Pennsylvania (state) USA (country) Networks and Protocols - Introduction

27. Access Networks and Physical Media • Residental access networks • Institutional access networks • Mobile access networks Networks and Protocols - Introduction

28. Residental Access Networks • Modem (telephone line, e.g. 56 kbps) • ISDN, 128 kbps • ADSL, up to 8Mbps using frequency Multiplexing • - A high speed downstream channel 50 kHz – 1 MHz • - A medium-speed upstream channel 4 kHz – 50 kHz • - Ordinary telephone 0 – 4 kHz. Networks and Protocols - Introduction

29. HFC: Hybrid Fiber coaxial cable Note: Cable modem needed! Note: HFC is a shared broadcast medium. Networks and Protocols - Introduction

30. Company Access Networks A Local Area Network (LAN) is used to connect end systems to an edge router. Ethernet: A shared medium using twisted-pair copper wire or coaxial cable. Networks and Protocols - Introduction

31. Mobile Access AP = Access Point. Networks and Protocols - Introduction

32. Delay and packet-loss Delay through router A: - nodal processing delay+ - Queuing delay + - Transmission delay+ - Propagation delay Networks and Protocols - Introduction

33. Traffic intensity Packet size: L bits Transmission Rate: R bits/second Average packet arrival: a packets / second Traffic intensity: La/R Hopefully: Traffic intensity < 1 If Traffic Intensity > 1 then queue will overflow and packets are lost. Networks and Protocols - Introduction

34. Average Queuing Delay (Traffic Intensity) Networks and Protocols - Introduction

35. Protocol Layering PDU = Protocol Data Unit. Networks and Protocols - Introduction

36. Internet Protocol stack Networks and Protocols - Introduction

37. Moving data in a network Networks and Protocols - Introduction

38. Course overview • Introduction (today) • Application Layer • Transport Layer • Network Layer • Link Layer + Physical Layer • Multimedia Networking • Security – Encryption • Network Management Networks and Protocols - Introduction