Data Communication and Computer Networking Part # 2
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This document discusses packet switching, layered models, and protocol suites used in computer networks. It describes the differences between circuit switching and packet switching. It explains how networking tasks are divided into layers, with each layer providing distinct functions. The document outlines the layers of the Internet protocol stack and OSI model, describing the responsibilities of each layer. It provides examples of common protocol suites like TCP/IP that ensure communication systems are complete and efficient.
Data Communication and Computer Networking Part # 2
- 1. jndqadar@gmail.comjndqadar@gmail.com Packet Switching, Layer ModelsPacket Switching, Layer Models and Protocol Suitesand Protocol Suites JUNAID QADARJUNAID QADAR MSC ELECTRONICSMSC ELECTRONICS Department of ElectronicsDepartment of Electronics UNIVERSITY OF PESHAWARUNIVERSITY OF PESHAWAR
- 2. 22 OutlineOutline Packet vs. circuit switchingPacket vs. circuit switching Layered tasksLayered tasks Internet protocol suitesInternet protocol suites ISO's OSI modelISO's OSI model
- 3. 33 Communication:Communication: App's ViewpointApp's Viewpoint Two network applications interact as ifTwo network applications interact as if there is a dedicate pipe connecting themthere is a dedicate pipe connecting them But what's going on underneath?But what's going on underneath? What is inside the "cloud"?What is inside the "cloud"? InternetInternet AA AppApp BB AppApp
- 4. 55 Circuit vs. Packet SwitchingCircuit vs. Packet Switching Dedicated circuitsDedicated circuits Circuit switchingCircuit switching Telephone switchesTelephone switches establish circuitsestablish circuits for communicationfor communication Packet switchingPacket switching Data are put intoData are put into packetspackets Each stamped withEach stamped with sourcesource andand destinationdestination addressesaddresses RoutersRouters know where toknow where to forward packetsforward packets telephone switch RouterPacket
- 5. 66 Layered TasksLayered Tasks Computer networks are complex systemsComputer networks are complex systems Tasks involve varieties of hardware andTasks involve varieties of hardware and software components, and protocolssoftware components, and protocols Networking task is divided into severalNetworking task is divided into several subtasks, or layerssubtasks, or layers
- 6. 77 Real World ExampleReal World Example Communication between managers of twoCommunication between managers of two companiescompanies Communicate
- 7. 88 What Actually HappensWhat Actually Happens Communication takes place thru many layersCommunication takes place thru many layers Logical communication Secretary: types a letter Delivery boy: drops the letter Secretary: reads and reports the message Delivery boy: takes the letter Post office: Processes and routes the letter Postal truck
- 8. 1111 Internet Layer ModelInternet Layer Model The Internet Protocol StackThe Internet Protocol Stack Application LayerApplication Layer Transport LayerTransport Layer Network LayerNetwork Layer Data Link LayerData Link Layer Physical LayerPhysical Layer User Transmission Medium Hardware Software
- 9. 1212 Application LayerApplication Layer The only layer to interact with userThe only layer to interact with user Responsible for providing services to the userResponsible for providing services to the userResponsible for providing services to the userResponsible for providing services to the user SMTP HTTP FTP SMTP HTTP FTP Data Data H5 Application Layer to Transport from Transport Data H5 Data Logical communication
- 10. 1313 Transport LayerTransport Layer Duties/servicesDuties/services Port addressingPort addressing Segmentation and reassemblySegmentation and reassembly Connection controlConnection control Flow control (end-to-end)Flow control (end-to-end) Error control (end-to-end)Error control (end-to-end) Responsible for delivery of a messageResponsible for delivery of a message from one process to anotherfrom one process to another Responsible for delivery of a messageResponsible for delivery of a message from one process to anotherfrom one process to another
- 11. 1414 Transport LayerTransport Layer Transport Layer Data from Application Data1 Data2 Data3H4 H4 H4 to Network Data to Application Data1 Data2 Data3H4 H4 H4 from Network (segments)
- 12. 1515 Network LayerNetwork Layer Duties/servicesDuties/services Logical addressingLogical addressing RoutingRouting Responsible for the delivery of packetsResponsible for the delivery of packets from the original source to the destinationfrom the original source to the destination Responsible for the delivery of packetsResponsible for the delivery of packets from the original source to the destinationfrom the original source to the destination
- 13. 1616 Network LayerNetwork Layer Network Layer Data from Transport to Data Link Data to Transport from Data Link Data H3 Data H3 (packet)
- 14. 1717 Network LayerNetwork Layer Network 1 Network 6 Network 5 1.1 1.2 6.6 6.1 6.3 5.7 5.2 Network 3 3.8 3.3 Router Data 1.1 5.7 1.1, 1.2, 6.1, 5.7, ... are logical addresses1.1, 1.2, 6.1, 5.7, ... are logical addresses R1 R3 R2
- 15. 1818 Data Link LayerData Link Layer Duties/servicesDuties/services FramingFraming Physical addressingPhysical addressing Flow control (hop-to-hop)Flow control (hop-to-hop) Error control (hop-to-hop)Error control (hop-to-hop) Access controlAccess control Responsible for transmitting framesResponsible for transmitting frames from one node to the nextfrom one node to the next Responsible for transmitting framesResponsible for transmitting frames from one node to the nextfrom one node to the next
- 16. 1919 Data Link LayerData Link Layer Data Link Layer Data from Network to Physical Data to Network from Physical Data H2 Data H2 (frame) T2 T2
- 17. 2020 Data Link LayerData Link Layer 3B A3, 3B, 82, 9F, ... are physical addressesA3, 3B, 82, 9F, ... are physical addresses 9F 82 A3 Data 9FT2 A3 Data H2
- 18. 2121 Data Link LayerData Link Layer Network 1 Network 6 Network 5 1.1 1.2 6.6 B1 6.3 5.7 5.2 Network 3 3.8 3.3 Data 1.15.7 97 32 25 79 62 54 74 12 88 Data 1.15.7 2597 Data 1.15.7 6279 Data 1.15.7 7454 R1 R3 R2
- 19. 2222 Physical LayerPhysical Layer Duties/servicesDuties/services Physical characteristics of interfacesPhysical characteristics of interfaces and mediaand media Representation of bitsRepresentation of bits Data rate (transmission rate)Data rate (transmission rate) Synchronization of bitsSynchronization of bits Responsible for transmitting individual bitsResponsible for transmitting individual bits from one node to the nextfrom one node to the next Responsible for transmitting individual bitsResponsible for transmitting individual bits from one node to the nextfrom one node to the next
- 20. 2323 Physical LayerPhysical Layer Physical Layer Data from Data Link to Data Link Data 01001011 01001011 Transmission medium (bits)
- 21. 2424 The Big PictureThe Big Picture L5 data H5 L4 data H4 L3 data H3 L2 dataT2 H2 0111011010101001010101001 L5 data H5 L4 data H4 L3 data H3 L2 dataT2 H2 0111010101010010101010101 5 4 3 2 1 5 4 3 2 1 Transmission medium
- 22. 2525 Internet ModelInternet Model ApplicationApplication TransportTransport NetworkNetwork Data LinkData Link PhysicalPhysical NetworkNetwork Data LinkData Link PhysicalPhysical NetworkNetwork Data LinkData Link PhysicalPhysical ApplicationApplication TransportTransport NetworkNetwork Data LinkData Link PhysicalPhysical Transmission medium sender router router receiver
- 23. 262626 Protocol SuitesProtocol Suites A set of protocols must be constructedA set of protocols must be constructed to ensure that the resulting communicationto ensure that the resulting communication system issystem is completecomplete andand efficientefficient Each protocol should handle a part ofEach protocol should handle a part of communication not handled by othercommunication not handled by other protocolsprotocols How can we guarantee that protocolsHow can we guarantee that protocols work well together?work well together? Instead of creating each protocol in isolation,Instead of creating each protocol in isolation, protocols are designed in complete,protocols are designed in complete, cooperative sets calledcooperative sets called suitessuites oror familiesfamilies
- 24. 2727 Internet Protocol SuiteInternet Protocol Suite LayerLayer ProtocolsProtocols ApplicationApplication HTTP, FTP, Telnet, SMTP, ...HTTP, FTP, Telnet, SMTP, ... TransportTransport TCP, UDP, SCTP, ...TCP, UDP, SCTP, ... NetworkNetwork IP (IPv4), IPv6, ICMP, IGMP, ...IP (IPv4), IPv6, ICMP, IGMP, ... Data LinkData Link Ethernet, Wi-Fi, PPP, ...Ethernet, Wi-Fi, PPP, ... PhysicalPhysical RS-232, DSL, 10Base-T, ...RS-232, DSL, 10Base-T, ...
- 25. 2828 OSI ModelOSI Model OSI –OSI – OOpenpen SSystemsystems IInterconnectionnterconnection Developed by theDeveloped by the IInternationalnternational SStandardstandards OOrganizationsrganizations (ISO)(ISO) Two additional layersTwo additional layers Presentation layerPresentation layer Session layerSession layer 7.Application Layer7.Application Layer 6.Presentation Layer6.Presentation Layer 5.Session Layer5.Session Layer 4.Transport Layer4.Transport Layer 3.Network Layer3.Network Layer 2.Data Link Layer2.Data Link Layer 1.Physical Layer1.Physical Layer User Transmission Medium
- 26. 2929 Session LayerSession Layer Duties/servicesDuties/services Interaction managementInteraction management Simplex, half-duplex, full-duplexSimplex, half-duplex, full-duplex Session recoverySession recovery Responsible for establishing, managing andResponsible for establishing, managing and terminating connections between applicationsterminating connections between applications Responsible for establishing, managing andResponsible for establishing, managing and terminating connections between applicationsterminating connections between applications
- 27. 3030 Presentation LayerPresentation Layer Duties/servicesDuties/services Data translationData translation EncryptionEncryption DecryptionDecryption CompressionCompression Responsible for handling differences inResponsible for handling differences in data representation to applicationsdata representation to applications Responsible for handling differences inResponsible for handling differences in data representation to applicationsdata representation to applications