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Feb. 4., 2002. Kåre J. KristoffersenNetworks and Protocols - Introduction1 Networks and Protocols - What is really going on when we send emails and surf the web?
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Feb. 4., 2002. Kåre J. KristoffersenNetworks and Protocols - Introduction2 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,-
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Feb. 4., 2002. Kåre J. KristoffersenNetworks and Protocols - Introduction3 Excercises and Instructors Rooms: 3.15 and 3.16, Glentevej 67. Monday Afternoon (13:00 – 15:30): Anders Ejlev, (anders@ejlev.dk)anders@ejlev.dk Monday Evening (19:00 – 21:30): Sune Kloppenborg Jeppesen, (jaervosz@it-c.dk)jaervosz@it-c.dk
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Feb. 4., 2002. Kåre J. KristoffersenNetworks and Protocols - Introduction4 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.
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Feb. 4., 2002. Kåre J. KristoffersenNetworks and Protocols - Introduction5 Outline feb 4. 2002 1.What is the internet? 2.What is a Protocol? 3.Connection-Oriented service. 4.Connectionless service. 5.Multiplexing. 6.Message switching (demo). 7.Packet switching (demo). 8.Routing. 9.Access Networks. 10.Delay and Packet loss i a network. 11.Protocol Layering. 12.Course overview.
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Feb. 4., 2002. Kåre J. KristoffersenNetworks and Protocols - Introduction6 Some Internet Applications Email Streaming multimedia www File transfer Internet telephony
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Feb. 4., 2002. Kåre J. KristoffersenNetworks and Protocols - Introduction7 Some pieces of the Internet
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Feb. 4., 2002. Kåre J. KristoffersenNetworks and Protocols - Introduction8 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.
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Feb. 4., 2002. Kåre J. KristoffersenNetworks and Protocols - Introduction9 What is a protocol? A human protocol and a computer network protocol.
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Feb. 4., 2002. Kåre J. KristoffersenNetworks and Protocols - Introduction10 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.
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Feb. 4., 2002. Kåre J. KristoffersenNetworks and Protocols - Introduction11 End systems, Clients and Servers
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Feb. 4., 2002. Kåre J. KristoffersenNetworks and Protocols - Introduction12 Connection-Oriented Service 1.Initial handshake. 2.Reliable data transfer, using acknowledgements. 3.Flow Control. 4.Congestion Control. Note: The Transmission Control Protocol (TCP) implements a connection- oriented service. Used by: Email, www, FTP, Telnet.
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Feb. 4., 2002. Kåre J. KristoffersenNetworks and Protocols - Introduction13 Connectionless Service 1.No Initial handshake. 2.Unreliable data transfer. 3.No Flow Control. 4.No Congestion Control. Used by: audio on demand, intertenet telephony, … Note: The User Datagram Protocol (UDP) implements a connectionless service.
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Feb. 4., 2002. Kåre J. KristoffersenNetworks and Protocols - Introduction14 The Network Core
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Feb. 4., 2002. Kåre J. KristoffersenNetworks and Protocols - Introduction15 How to share a communication link? 1.In Curcuit switching (e.g. ordinary telephone) a curcuit is reserved for the duration of the session. 2.In Packet switching (e.g. internet) the ressource is used on demand. Note: Sharing is called Multiplexing.
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Feb. 4., 2002. Kåre J. KristoffersenNetworks and Protocols - Introduction16 Multiplexing (FDM) Frequency-division multiplexing (FDM): Each Connection gets 4 KHz of the total frequency spectrum.
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Feb. 4., 2002. Kåre J. KristoffersenNetworks and Protocols - Introduction17 Multiplexing (TDM) Time-division Multiplexing: Each connection get one slot in each Frame. Frame
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Feb. 4., 2002. Kåre J. KristoffersenNetworks and Protocols - Introduction18 Multiplexing for Packetswitching.
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Feb. 4., 2002. Kåre J. KristoffersenNetworks and Protocols - Introduction19 Message Switching
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Feb. 4., 2002. Kåre J. KristoffersenNetworks and Protocols - Introduction20 Packet switching
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Feb. 4., 2002. Kåre J. KristoffersenNetworks and Protocols - Introduction21 Example: Message Switching
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Feb. 4., 2002. Kåre J. KristoffersenNetworks and Protocols - Introduction22 Example: Packet Switching
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Feb. 4., 2002. Kåre J. KristoffersenNetworks and Protocols - Introduction23 Demo: Packet Switching Run the JAVA Applet on: http://www.awl.com/kurose-ross/
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Feb. 4., 2002. Kåre J. KristoffersenNetworks and Protocols - Introduction24 Break Table Tennis Table soccer
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Feb. 4., 2002. Kåre J. KristoffersenNetworks and Protocols - Introduction25 Routing: Virtual Curcuit Networks Incoming InterfaceIncoming VC#Outgoing InterfaceOutgoing VC# 112322 263118 37217 197387 ………… VC number translation table for PS1:
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Feb. 4., 2002. Kåre J. KristoffersenNetworks and Protocols - Introduction26 Routing: Datagram Networks Tom Jones(name) Walnut Street 421 (street) Philadelphia(city) Pennsylvania (state) USA(country) Using: Hierarchical adresse, e.g:
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Feb. 4., 2002. Kåre J. KristoffersenNetworks and Protocols - Introduction27 Access Networks and Physical Media Residental access networks Institutional access networks Mobile access networks
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Feb. 4., 2002. Kåre J. KristoffersenNetworks and Protocols - Introduction28 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.
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Feb. 4., 2002. Kåre J. KristoffersenNetworks and Protocols - Introduction29 HFC: Hybrid Fiber coaxial cable Note: Cable modem needed! Note: HFC is a shared broadcast medium.
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Feb. 4., 2002. Kåre J. KristoffersenNetworks and Protocols - Introduction30 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.
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Feb. 4., 2002. Kåre J. KristoffersenNetworks and Protocols - Introduction31 Mobile Access AP = Access Point.
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Feb. 4., 2002. Kåre J. KristoffersenNetworks and Protocols - Introduction32 Delay and packet-loss Delay through router A: - nodal processing delay+ - Queuing delay + - Transmission delay+ - Propagation delay
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Feb. 4., 2002. Kåre J. KristoffersenNetworks and Protocols - Introduction33 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.
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Feb. 4., 2002. Kåre J. KristoffersenNetworks and Protocols - Introduction34 Average Queuing Delay (Traffic Intensity)
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Feb. 4., 2002. Kåre J. KristoffersenNetworks and Protocols - Introduction35 Protocol Layering PDU = Protocol Data Unit.
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Feb. 4., 2002. Kåre J. KristoffersenNetworks and Protocols - Introduction36 Internet Protocol stack
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Feb. 4., 2002. Kåre J. KristoffersenNetworks and Protocols - Introduction37 Moving data in a network
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Feb. 4., 2002. Kåre J. KristoffersenNetworks and Protocols - Introduction38 Course overview Introduction (today) Application Layer Transport Layer Network Layer Link Layer + Physical Layer Multimedia Networking Security – Encryption Network Management
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