Unit I networks

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Network Hardware, Network Software, OSI Reference Model, TCP / IP model

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Unit I networks

  1. 1. Loyola College, Vettavalam. C - Programming Language By REX
  2. 2. Set of devices communicating with each other. Could be a CPU, monitor and other peripheral devices connected (and exchanging data) to each other. Could be a group of people …. A network of friends. Or, could be a set of computers communicating with each other. What is a network? Loyola College, Vettavalam.
  3. 3. On the basis of Applications Model Size of Geographical Area covered Classification of Networks Loyola College, Vettavalam.
  4. 4. Business Applications Home Applications Mobile Users Social Issues Uses of Computer Networks Loyola College, Vettavalam.
  5. 5. . Some forms of e-commerce Loyola College, Vettavalam.
  6. 6. Access to remote information(WWW etc) Person-to-person communication(Email, Instant Messaging etc, Phone) Interactive entertainment(Remote operated or online Games) Electronic commerce Home Network Applications Loyola College, Vettavalam.
  7. 7. Combinations of wireless networks and mobile computing. Mobile Network Users Loyola College, Vettavalam.
  8. 8. Client Server Model : A network with two clients and one server: Employees accessing company’s Information System Business Applications of Networks Loyola College, Vettavalam.
  9. 9. The client-server model involves requests and replies. Business Applications of Networks (2) Loyola College, Vettavalam.
  10. 10. In peer-to-peer system there are no fixed clients and servers. Peer-to-Peer Model of Communication Loyola College, Vettavalam.
  11. 11. Local Area Networks Metropolitan Area Networks Wide Area Networks Internetworks Network Hardware Loyola College, Vettavalam.
  12. 12. Types of transmission technology Broadcast links Point-to-point links Broadcast Networks Loyola College, Vettavalam.
  13. 13. Broadcast Networks (2) Classification of interconnected processors by scale. Loyola College, Vettavalam.
  14. 14. Two broadcast networks (a) Bus (b) Ring Local Area Networks Loyola College, Vettavalam.
  15. 15. A metropolitan area network based on cable TV. Metropolitan Area Networks Loyola College, Vettavalam.
  16. 16. Relation between hosts on LANs and the subnet. Wide Area Networks Loyola College, Vettavalam.
  17. 17. A stream of packets from sender to receiver. Wide Area Networks (2) Loyola College, Vettavalam.
  18. 18. Categories of wireless networks: System interconnection(Bluetooth) Wireless LANs Wireless WANs Wireless Networks Loyola College, Vettavalam.
  19. 19. (a) Bluetooth configuration (b) Wireless LAN Wireless Networks (2) Loyola College, Vettavalam.
  20. 20. (a) Individual mobile computers (b) A flying LAN Wireless Networks (3) Loyola College, Vettavalam.
  21. 21. 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). Home Network Categories Loyola College, Vettavalam.
  22. 22. Protocol Hierarchies Design Issues for the Layers Connection-Oriented and Connectionless Services Service Primitives The Relationship of Services to Protocols Network Software Loyola College, Vettavalam.
  23. 23. OSI Model
  24. 24. Open Systems Interconnection (OSI) is a set of internationally recognized, non-proprietary standards for networking and for operating system involved in networking functions. Loyola College, Vettavalam.
  25. 25. 7 Layers 7. Application Layer Presentation Layer Session Layer Transport Layer Network Layer Data Link Layer Physical Layer All People Seem To Need Data Processing Loyola College, Vettavalam.
  26. 26. Tasks involved in sending letter Loyola College, Vettavalam.
  27. 27. The top layer of the OSI model Provides a set of interfaces for sending and receiving applications to gain access to and use network services, such as: networked file transfer, message handling and database query processing LAYER 7 – The APPLICATION Layer The application layer is responsible for providing services to the user. Loyola College, Vettavalam.
  28. 28. Manages data-format information for networked communications (the network’s translator) For outgoing messages, it converts data into a generic format for network transmission; for incoming messages, it converts data from the generic network format to a format that the receiving application can understand This layer is also responsible for certain protocol conversions, data encryption/decryption, or data compression/decompression A special software facility called a “redirector” operates at this layer to determine if a request is network related on not and forward network-related requests to an appropriate network resource LAYER 6 – The PRESENTATION Layer The presentation layer is responsible for translation, compression, and encryption. Loyola College, Vettavalam.
  29. 29. Enables two networked resources to hold ongoing communications (called a session) across a network Applications on either end of the session are able to exchange data for the duration of the session This layer is: Responsible for initiating, maintaining and terminating sessions Responsible for security and access control to session information (via session participant identification) Responsible for synchronization services, and for checkpoint services LAYER 5 – The SESSION Layer The session layer is responsible for dialog control and synchronization. Loyola College, Vettavalam.
  30. 30. Manages the transmission of data across a network Manages the flow of data between parties by segmenting long data streams into smaller data chunks (based on allowed “packet” size for a given transmission medium) Reassembles chunks into their original sequence at the receiving end Provides acknowledgements of successful transmissions and requests resends for packets which arrive with errors LAYER 4 – The TRANSPORT Layer The transport layer is responsible for the delivery of a message from one process to another. Loyola College, Vettavalam.
  31. 31. Handles addressing messages for delivery, as well as translating logical network addresses and names into their physical counterparts Responsible for deciding how to route transmissions between computers This layer also handles the decisions needed to get data from one point to the next point along a network path This layer also handles packet switching and network congestion control LAYER 3 – The NETWORK Layer The network layer is responsible for the delivery of individual packets from the source host to the destination host. Loyola College, Vettavalam.
  32. 32. Handles special data frames (packets) between the Network layer and the Physical layer At the receiving end, this layer packages raw data from the physical layer into data frames for delivery to the Network layer At the sending end this layer handles conversion of data into raw formats that can be handled by the Physical Layer LAYER 2 – The DATA LINK Layer The data link layer is responsible for moving frames from one hop (node) to the next. Loyola College, Vettavalam.
  33. 33. Converts bits into electronic signals for outgoing messages Converts electronic signals into bits for incoming messages This layer manages the interface between the the computer and the network medium (coax, twisted pair, etc.) This layer tells the driver software for the MAU (media attachment unit, ex. network interface cards (NICs, modems, etc.)) what needs to be sent across the medium The bottom layer of the OSI model LAYER 1 – The PHYSICAL Layer The physical layer is responsible for movements of individual bits from one hop (node) to the next. Loyola College, Vettavalam.
  34. 34. A convenient aid for remembering the OSI layer names is to use the first letter of each word in the phrase: All People Seem To Need Data Processing Remember Loyola College, Vettavalam.
  35. 35. Layers, protocols, and interfaces. Network SoftwareProtocol Hierarchies Loyola College, Vettavalam.
  36. 36. Protocol Hierarchies (2) The philosopher-translator-secretary architecture. Loyola College, Vettavalam.
  37. 37. Example information flow supporting virtual communication in layer 5. Protocol Hierarchies (3) Loyola College, Vettavalam.
  38. 38. Design Issues for the Layers Addressing Error Control Flow Control Multiplexing Routing Loyola College, Vettavalam.
  39. 39. Six different types of service. Connection-Oriented and Connectionless Services Loyola College, Vettavalam.
  40. 40. Five service primitives for implementing a simple connection-oriented service. Service Primitives Loyola College, Vettavalam.
  41. 41. Packets sent in a simple client-server interaction on a connection-oriented network. Service Primitives (2) Loyola College, Vettavalam.
  42. 42. The relationship between a service and a protocol. Services to Protocols Relationship Loyola College, Vettavalam.
  43. 43. 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 Reference Models Loyola College, Vettavalam.
  44. 44. Reference Models The OSI reference model. Loyola College, Vettavalam.
  45. 45. The TCP/IP reference model. Reference Models (2) Loyola College, Vettavalam.
  46. 46. Protocols and networks in the TCP/IP model initially. Reference Models (3) Loyola College, Vettavalam.
  47. 47. Concepts central to the OSI model Services Interfaces Protocols Comparing OSI and TCP/IP Models Loyola College, Vettavalam.
  48. 48. Why OSI did not take over the world Bad timing Bad technology Bad implementations Bad politics A Critique of the OSI Model and Protocols Loyola College, Vettavalam.
  49. 49. The apocalypse of the two elephants. Bad Timing Loyola College, Vettavalam.
  50. 50. 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 Loyola College, Vettavalam.
  51. 51. The hybrid reference model to be used in this book. Hybrid Model Loyola College, Vettavalam.
  52. 52. The Internet Connection-Oriented Networks: X.25, Frame Relay, and ATM Ethernet Wireless LANs: 802:11 Example Networks Loyola College, Vettavalam.
  53. 53. (a) Structure of the telephone system. (b)Baran’s proposed distributed switching system. The ARPANET(Advanced Research Project Agency Net) Loyola College, Vettavalam.
  54. 54. The original ARPANET design. The ARPANET (2) Loyola College, Vettavalam. Loyola College, Vettavalam.
  55. 55. The ARPANET (3) Growth of the ARPANET (a) December 1969. (b) July 1970. (c) March 1971. (d) April 1972. (e) September 1972. Loyola College, Vettavalam.
  56. 56. The NSFNET backbone in 1988. NSFNET Loyola College, Vettavalam.
  57. 57. Traditional applications (1970 – 1990) E-mail News Remote login File transfer Internet Usage Loyola College, Vettavalam.
  58. 58. Overview of the Internet. Architecture of the Internet Loyola College, Vettavalam.
  59. 59. A virtual circuit. ATM Virtual Circuits Loyola College, Vettavalam.
  60. 60. An ATM cell. ATM Virtual Circuits (2) Loyola College, Vettavalam.
  61. 61. The ATM reference model. The ATM Reference Model Loyola College, Vettavalam.
  62. 62. The ATM layers and sublayers and their functions. The ATM Reference Model (2) Loyola College, Vettavalam.
  63. 63. Architecture of the original Ethernet. Ethernet Loyola College, Vettavalam.
  64. 64. (a) Wireless networking with a base station. (b) Ad hoc networking. Wireless LANs Loyola College, Vettavalam.
  65. 65. The range of a single radio may not cover the entire system. Wireless LANs (2) Loyola College, Vettavalam.
  66. 66. 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. Loyola College, Vettavalam.
  67. 67. The principal metric prefixes. Metric Units Loyola College, Vettavalam.
  68. 68. 2.2 THE OSI MODEL Established in 1947, the International Standards Organization (ISO) is a multinational body dedicated to worldwide agreement on international standards. An ISO standard that covers all aspects of network communications is the Open Systems Interconnection (OSI) model. It was first introduced in the late 1970s. Loyola College, Vettavalam.
  69. 69. Layered Architecture The OSI model is composed of seven layers ; Physical (layer1), Data link (layer2), Network (layer3) Transport (layer4), Session (layer5), Presentation (layer6) Application (layer7) Layer Designer identified which networking functions had related uses and collected those functions into discrete groups that became the layers. The OSI model allows complete interoperability between otherwise incompatible systems. The Each layer uses the services of the layer immediately below it. Loyola College, Vettavalam.
  70. 70. Layered Architecture (cont’d) Figure 2.2Seven layers of the OSI model Loyola College, Vettavalam.
  71. 71. Peer-to-peer Processes Layer x on one machine communicates with layer x on another machine - called Peer-to-Peer Processes. Interfaces between Layers Each interface defines what information and services a layer must provide for the layer above it. Well defined interfaces and layer functions provide modularity to a network Organizations of the layers Network support layers : Layers 1, 2, 3 User support layer : Layer 5, 6, 7 It allows interoperability among unrelated software systems Transport layer (Layer 4) : links the two subgroups Loyola College, Vettavalam.
  72. 72. Peer-to-peer Processes (cont’d) Figure 2.3The interaction between layers in the OSI model Loyola College, Vettavalam.
  73. 73. Peer-to-peer Processes (cont’d) Figure 2.4An exchange using the OSI model The data portion of a packet at level N-1 carries the whole packet from level N. – The concept is called encapsulation. Loyola College, Vettavalam.
  74. 74. 2.3 LAYERS IN THE OSI MODEL In this section we briefly describe the functions of each layer in the OSI model. Topics discussed in this section: Physical LayerData Link Layer Network Layer Transport Layer Session Layer Presentation Layer Application Layer Loyola College, Vettavalam.
  75. 75. Physical Layer Physical layer coordinates the functions required to transmit a bit stream over a physical medium. The physical layer is responsible for movements of individual bits from one hop (node) to the next. Loyola College, Vettavalam.
  76. 76. Physical Layer Physical layer is concerned with the following: (deal with the mechanical and electrical specification of the primary connections: cable, connector) Physical characteristics of interfaces and medium Representation of bits Data rate : transmission rate Synchronization of bits Line configuration Physical topology Transmission mode Loyola College, Vettavalam.
  77. 77. Data Link Layer The data link layer is responsible for moving frames from one hop (node) to the next. Loyola College, Vettavalam.
  78. 78. Data Link Layer Major duties Framing Physical addressing Flow control Error control Access control Loyola College, Vettavalam.
  79. 79. Data Link Layer Hop-to-hop (node-to-node) delivery Loyola College, Vettavalam.
  80. 80. Network Layer Loyola College, Vettavalam.
  81. 81. Network Layer Logical addressing Routing Loyola College, Vettavalam.
  82. 82. Transport Layer The transport layer is responsible for the delivery of a message from one process to another. Loyola College, Vettavalam.
  83. 83. Transport Layer Loyola College, Vettavalam.
  84. 84. Transport Layer Service port addressing Segmentation and reassembly Connection control Flow control Error control Loyola College, Vettavalam.
  85. 85. Session Layer The session layer is responsible for dialog control and synchronization. Loyola College, Vettavalam.
  86. 86. Presentation Layer The presentation layer is responsible for translation, compression, and encryption Loyola College, Vettavalam.
  87. 87. TCP/IP Protocol Suite Figure 2.16TCP/IP and OSI model Loyola College, Vettavalam.
  88. 88. Physical Addresses Figure 2.18Relationship of layers and addresses in TCP/IP Loyola College, Vettavalam.
  89. 89. Logical Addresses (cont’d) Figure 2.20IP addresses The physical addresses will change from hop to hop, but the logical addresses usually remain the same. Loyola College, Vettavalam.
  90. 90. Port Addresses (cont’d) Figure 2.21Port addresses The physical addresses will change from hop to hop, but the logical and port addresses usually remain the same. Loyola College, Vettavalam.

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