1. Chapter 1
Introduction

2. Uses of Computer Networks
Business Applications
Home Applications
Mobile Users
Social Issues

3. Business Applications of Networks
A network with two clients and one server.

4. Business Applications of Networks (2)
The client-server model involves requests and replies.

5. Home Network Applications
Access to remote information
Person-to-person communication
Interactive entertainment
Electronic commerce

6. Home Network Applications (2)
In peer-to-peer system there are no fixed clients and servers.

7. Home Network Applications (3)
Some forms of e-commerce.

8. Combinations of wireless networks and mobile computing.
Mobile Network Users
Combinations of wireless networks and mobile computing.

9. Network Hardware Local Area Networks Metropolitan Area Networks
Wide Area Networks
Wireless Networks
Home Networks
Internetworks

10. Broadcast Networks Types of transmission technology Broadcast links
Point-to-point links

11. Classification of interconnected processors by scale.
Broadcast Networks (2)
Classification of interconnected processors by scale.

12. Local Area Networks
Two broadcast networks
(a) Bus
(b) Ring

13. Broadcast Network
Static and Dynamic Static – Divide time into discrete intervals, - Use Round Robin Disadvantage - wastes channel capacity Dynamic Allocation Centralized or Decentralized Centralized – A Bus Arbitration Unit Decentralized – No central entity, each machine decides for itself

14. Metropolitan Area Networks
A metropolitan area network based on cable TV.

15. Relation between hosts on LANs and the subnet.
Wide Area Networks
Relation between hosts on LANs and the subnet.

16. Wide Area Network
Subnet Transmission Lines – move bits between machines Switching Elements – Connect three or more transmission lines Router Subnet – Collection of Communication Lines and Routers Different from Subnet ip

17. A stream of packets from sender to receiver.
Wide Area Networks (2)
A stream of packets from sender to receiver.

18. Wide Area Network
Store and Forward or Packet-Switched When a packet is sent from one router to the other via one or more intermediate router in its entirety, stored there until the required output is free. Message divided into packets Satellite connection

19. Wireless Networks Categories of wireless networks:
System interconnection
Wireless LANs
Wireless WANs

20. Wireless Networks (2)
Bluetooth configuration
Master Slave Paradigm – Master tells the slave what address to use what frequency they can use and when they can broadcast

21. Wireless Networks (3) Wireless LAN – 802.11
(a) Individual mobile computers
(b) A flying LAN

22. 3G Cellular Network – both voice and data (low-speed network)
Wireless WAN
3G Cellular Network – both voice and data (low-speed network)

23. Home Network Categories
Computers (desktop PC, PDA, shared peripherals
Entertainment (TV, DVD, VCR, camera, stereo, MP3)
Telecomm (telephone, cell phone, intercom, fax)
Appliances (microwave, fridge, clock, furnace, airco)
Telemetry (utility meter, burglar alarm, babycam).

24. Features of Home Network
Network and devices have to be easy to install
Read the Manual
Reboot the computer
Remove all the hardware and software except ours and try again
Download Newest driver
Reformat the harddisk
Networks and Devices have to be foolproof in operation
(no big manuals)
Low Price (will pay a little extra atmost)

25. Features of Home Network
Main application is likely to involve multimedia, so the network needs sufficient capacity Possible to start out with one or two devices and expand the reach Security and reliability will be very important Burglars disarm ones security

26. Internetworks
Some LANS connected through WANS Distinct networks are connected

27. Network Software Protocol Hierarchies Design Issues for the Layers
Connection-Oriented and Connectionless Services
Service Primitives
The Relationship of Services to Protocols

28. Network Software Protocol Hierarchies
Layers, protocols, and interfaces.

29. Protocol Hierarchies (2)
The philosopher-translator-secretary architecture.

30. Protocol Hierarchies (3)
Example information flow supporting virtual communication in layer 5.

31. Design Issues for the Layers
Addressing
Error Control
Flow Control
Multiplexing
Routing

32. Connection-Oriented and Connectionless Services
Connection – oriented (telephonic system) Sender, receiver and subnet needs to have a negotiation about the parameters to be used such as maximum message size, quality of services required and other issues Connection-less (postal service) Quality of Service

33. Connection-Oriented and Connectionless Services
Request-reply – Client issues request, server answers.
Six different types of service.

34. Service Primitives
Listen – server, Connect – client to server and then connection is established
Five service primitives for implementing a simple connection-oriented service.

35. Service Primitives (2)
Packets sent in a simple client-server interaction on a connection-oriented network.

36. Difficulties
Unreliable networks Synchronization problem

37. Services to Protocols Relationship
Service – Abstract Data Type or an object in an object-oriented language
The relationship between a service and a protocol.

38. Reference Models The OSI Reference Model The TCP/IP Reference Model
A Comparison of OSI and TCP/IP
A Critique of the OSI Model and Protocols
A Critique of the TCP/IP Reference Model

39. A layer is created where a different abstraction is needed Each layer should perform a well-defined function The function of each layer should be chosen with an eye toward defining internationally standardized protocols The layer boundary should be chosen to minimize the information flow across interfaces The number of layers should be large enough that distinct functions need not be thrown together out of necessity and small enough that the architecture does not become unweildy

40. The OSI reference model.
Reference Models
The OSI reference model.

41. Physical Layer (questions)
How many volts should be used to represent 1 How many nanoseconds a bit lasts Transmission may proceed in one direction or multiple direction How intitial connection established How many pins the network connector has

42. DataLink
Raw transmission facility in a line that appears free of undetected errors to the network layer. Data frames  acknowledgement frame

43. The TCP/IP reference model.
Reference Models (2)
The TCP/IP reference model.

44. Protocols and networks in the TCP/IP model initially.
Reference Models (3)
Protocols and networks in the TCP/IP model initially.

45. IP – Packet Switching Transport Layer – TCP – Flow control UDP – Fast Delivery

46. Comparing OSI and TCP/IP Models
Concepts central to the OSI model
Services
Interfaces
Protocols
TCP – retrofit/
OSI – DataLink Layer (point-to-point)

47. Differences between OSI and TCP/IP model
OSI model supports connectionless and connection-oriented communication in the network layer but only connection-oriented communication in the transport layer TCP/IP model has one mode in the network layer (connectionless) but supports both modes in the transport layer

48. A Critique of the OSI Model and Protocols
Why OSI did not take over the world
Bad timing
Bad technology
Bad implementations
Bad politics

49. The apocalypse of the two elephants. (Standard came much later)
Bad Timing
The apocalypse of the two elephants. (Standard came much later)

50. Bad Implementation
Initial version were huge, unwieldy and slow. Bad Politics TCP/IP part of Unix, OSI – governement pushed

51. A Critique of the TCP/IP Reference Model
Problems:
Service, interface, and protocol not distinguished
Not a general model
Host-to-network “layer” not really a layer
No mention of physical and data link layers
Minor protocols deeply entrenched, hard to replace

52. The hybrid reference model to be used in this book.
Hybrid Model
The hybrid reference model to be used in this book.

53. Example Networks The Internet
Connection-Oriented Networks: X.25, Frame Relay, and ATM
Ethernet
Wireless LANs: 802:11

54. The ARPANET (a) Structure of the telephone system.
(b) Baran’s proposed distributed switching system.

55. The original ARPANET design.
The ARPANET (2)
The original ARPANET design.

56. The ARPANET (3)
Growth of the ARPANET (a) December (b) July 1970.
(c) March (d) April (e) September 1972.

57. NSFNET
The NSFNET backbone in 1988.

58. Internet Usage Traditional applications (1970 – 1990) E-mail News
Remote login
File transfer

59. Architecture of the Internet
Overview of the Internet.

60. ATM Virtual Circuits
A virtual circuit.

61. ATM Virtual Circuits (2)
An ATM cell.

62. The ATM Reference Model

63. The ATM Reference Model (2)
The ATM layers and sublayers and their functions.

64. Architecture of the original Ethernet.

65. Wireless LANs (a) Wireless networking with a base station.
(b) Ad hoc networking.

66. The range of a single radio may not cover the entire system.
Wireless LANs (2)
The range of a single radio may not cover the entire system.

67. Wireless LANs (3)
A multicell network.

68. Network Standardization
Who’s Who in the Telecommunications World
Who’s Who in the International Standards World
Who’s Who in the Internet Standards World

69. ITU Main sectors Classes of Members Radiocommunications
Telecommunications Standardization
Development
Classes of Members
National governments
Sector members
Associate members
Regulatory agencies

70. IEEE 802 Standards
The 802 working groups. The important ones are marked with *. The ones marked with  are hibernating. The one marked with † gave up.

71. The principal metric prefixes.
Metric Units
The principal metric prefixes.