1. M. R. Kharazmi Chapter 1 Data Communications and Networks Overview

2. Book Computer Networking:A Top Down Approach Featuring the Internet, 3nd edition. Jim Kurose, Keith Ross Addison-Wesley, July 2002. Communications and Networking, 3rd edition, Behrouz A Forouzan, McGraw-Hill. ISBN 007-123241-9. Course Material

3. Information and Data Information—many meanings Information is: -the necessary property of a message, it includes something to be communicated from the sender to the receiver - any represented pattern -any type of sensory input - Any type of pattern that influences the formation or transformation of other patterns Data Representation of information Symbols with a certain syntax

4. Communication Sharing or transfer of information “Telecommunication” Communication at a distance Traditionally speach Sound, pictures, text,... “Communications” “The branch of technology concerned with the representation, transfer, interpretation, and processing of data among persons, places, and machines also known as information systems.” ”Data communications” ” the exchange of data between two devices over some form of transmission medium”

5. A Communications Model Source generates data to be transmitted Transmitter Converts data into transmittable signals Transmission System Carries data Receiver Converts received signal into data Destination Takes incoming data

6. Communications Tasks Transmission system utilizationAddressing InterfacingRouting Signal generationRecovery SynchronizationMessage formatting Exchange managementSecurity Error detection and correctionNetwork management Flow control

7. Communications Tasks Ways to transfer information on a link Signal format Addressing Identify sender and receiver Routing Find a path between sender and receiver Buffering Compensate for differences in speed Variations in traffic load Error detection and control If data is lost or corrupted Congestion control To protect the network from being overloaded Management and network operations

8. Signals

9. Sine Wave

10. Time and Frequency Domains

11. Composite Signals

12. Fourier Analysis Any composite signal can be represented as a sum of simple sine waves

13. Bandwidth Important property of a medium Difference between highest and lowest frequency that can pass through the medium Measured in Hertz [Hz] Limits the channel’s capaci

14. Simplified Communications Model - Diagram

15. Simplified Data Communications Model

16. Requirements on Communication

17. Connectivity

18. Point-to-point Connections

19. Multipoint Connection

20. Networking Aset of nodes connected by links Hosts, switches, routers, stations, Need devices between sender and receiver Signals regeneration and amplification Different equipment, formats, etc Sharing of links Routing, addressing, traffic control,... Links form a topology Distributed processing Tasks are divided among multiple units (computers)

21. Physical Topologies

22. Mesh Topology

23. Star Topology All links to a central node (hub) Common office installation today Advantages Less costly than mesh Easy to install and maintain Disadvantages Hub is single point of failure One cable from each node to hub

24. Bus Topology

26. Network Types Classification depends on: Ownership Size and distance Physical architecture

27. Local Area Networks (LANs)

28. Metropolitan Area Network (MAN)

29. Wide Area Networks Large geographical area Crossing public rights of way Rely in part on common carrier circuits Alternative technologies Circuit switching Packet switching Frame relay Asynchronous Transfer Mode (ATM)

30. Kurose CH.1

31. Circuit Switching Dedicated communications path established for the duration of the conversation e.g. telephone network

32. Packet Switching Data sent out of sequence Small chunks (packets) of data at a time Packets passed from node to node between source and destination Used for terminal to computer and computer to computer communications

33. Frame Relay Packet switching systems have large overheads to compensate for errors Modern systems are more reliable Errors can be caught in end system Most overhead for error control is stripped out

34. Asynchronous Transfer Mode ATM Evolution of frame relay Little overhead for error control Fixed packet (called cell) length Anything from 10Mbps to Gbps Constant data rate using packet switching technique

35. Local Area Networks Smaller scope Building or small campus Usually owned by same organization as attached devices Data rates much higher Usually broadcast systems Now some switched systems and ATM are being introduced

36. LAN Configurations Switched Switched Ethernet May be single or multiple switches ATM LAN Fibre Channel Wireless Mobility Ease of installation

37. Metropolitan Area Networks MAN Middle ground between LAN and WAN Private or public network High speed Large area

38. Networking Configuration