Comp net 1


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This is the first lecture of Advanced Computer Network .
the Book is :Computer Networks 4th Ed - by : Andrew S. Tanenbaum

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Comp net 1

  1. 1. Computer Network Course Lecture 1 Introduction
  2. 2. 5/2/2014 2 Computer Network Why network Communications Model Network types Network Software Layering Protocol Stack models A network is a set of devices (often referred to as nodes) connected by communication links. A node can be a computer, printer, or any other device capable of sending and/or receiving data generated by other nodes on the network. A link can be a cable, air, optical fiber, or any medium which can transport a signal carrying information.
  3. 3. 5/2/2014 3 Why Network Resource Sharing Reliability and Availability Communication Medium Access Information E- Commerce Person to Person Communication Others
  4. 4. Some of Network applications 5/2/2014
  5. 5. 5/2/2014 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. 6. 5/2/2014 6 Simplified Communications Model - Diagram
  7. 7. 5/2/2014 7 Simplified Data Communications Model
  8. 8. 5/2/2014 8 Types of Networks Classification according to the covered distance
  9. 9. 5/2/2014 9 Type of Networks Classification according to the access techniques Point to Point (Switched) Network • Circuit switched networks • Packet switched networks Broadcast Network • Local Area Networks • Wireless LAN • Satellite networks
  10. 10. 5/2/2014 10 Type of Networks:
  11. 11. 5/2/2014 11
  12. 12. 5/2/2014 12 Broadcast Networks
  13. 13. Network Software Protocol Hierarchies Design Issues for the Layers Connection-Oriented and Connectionless Services Service Primitives The Relationship of Services to Protocols
  14. 14. Protocol Key Features of a Protocol Syntax • Concerns the format of the data blocks • Indicates how to read the bits - field delineation Semantics • Includes control information for coordination and error handling Timing • Includes speed matching and sequencing
  15. 15. Protocol Hierarchies Layers, protocols, and interfaces. The job of sending message from source to destination would be complex without divided the job into tasks, using the concept of Layers
  16. 16. Protocol Hierarchies Example: information flow
  17. 17. Design Issues for the Layers Addressing Error Control Flow Control Multiplexing Routing
  18. 18. Connection-Oriented and Connectionless Services 5/2/2014 18 Unacknowledged connectionless service. Acknowledged connectionless service. Acknowledged connection-oriented service. Connection-Less Connection Oriented AcknowledgedUN-Acknowledged “Best Effort” Better Quality Reliable Delivery
  19. 19. Service Primitives Five service primitives for implementing a simple connection-oriented service.
  20. 20. Service Primitives Packets sent in a simple client-server interaction on a connection-oriented network.
  21. 21. Relationship of Services to Protocols
  22. 22. Reference Models The OSI Reference Model The TCP/IP Reference Model A Comparison of OSI and TCP/IP
  23. 23. The OSI reference model.
  24. 24. 5/2/2014 24 OSI Application Layer Provides access to the OSI environment for users Provides distributed information services OSI Presentation Layer Provides independence to the application processes from differences in data representation (syntax) OSI Session Layer Provides the control structure for communication between applications Establishes, manages, and terminates connections (sessions) between cooperating applications
  25. 25. 25 OSI Transport Layer Provides reliable, transparent transfer of data between end points Provides end-to-end error recovery and flow control OSI Network Layer Provides upper layers with independence from the data transmission and switching technologies used to connect systems Responsible for establishing, maintaining, and terminating connections OSI Data link Layer Provides for the reliable transfer of information across the physical link Sends blocks (frames) with the necessary synchronization, error control, and flow control
  26. 26. 5/2/2014 26 OSI Physical Layer Concerned with transmission of unstructured bit stream over physical medium Deals with accessing the physical medium  Mechanical characteristics  Electrical characteristics  Functional characteristics  Procedural characteristics
  27. 27. The TCP/IP reference model. 5/2/2014
  28. 28. Protocols and networks in the TCP/IP model initially.
  29. 29. The reference model to be used in this course. 5/2/2014