1 / 77

Introduction to Computer Networks

Introduction to Computer Networks. 講義網址 http://www.ee.cgu.edu.tw/member/teacher/mfli/index.htm 參考網頁 http://cherry.cs.nccu.edu.tw/~lien/NIIslide.htm. Classification of Computer Networks Network Structure Network Architecture The OSI Reference Model The DoD TCP/IP Model Network Terminologies

damisi
Download Presentation

Introduction to Computer Networks

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Introduction to Computer Networks 講義網址http://www.ee.cgu.edu.tw/member/teacher/mfli/index.htm 參考網頁http://cherry.cs.nccu.edu.tw/~lien/NIIslide.htm • Classification of Computer Networks • Network Structure • Network Architecture • The OSI Reference Model • The DoD TCP/IP Model • Network Terminologies • An Overview of Reliable Data Transfer • Network Addressing • Routing • MAC Protocols

  2. Introduction • What is computer networks? A system consists of two or more autonomous computers/equipment interconnected by transmission media (e.g., coaxial cable, fiber, twisted pair, microwave) . • What is the goals of computer networks? Resource sharing High reliability Economic efficiency

  3. Introduction • PSTN (Public Switched Telephone Networks)

  4. Introduction • PSTN (Public Switched Telephone Networks)

  5. Introduction • Antique Phones

  6. Introduction • Antique Switches

  7. Introduction • IP Networks (Internet)

  8. Introduction • IP Network Architecture

  9. Introduction • Integrated Services via ADSL

  10. Introduction • Integrated Services via ADSL

  11. Introduction • Triple Play Services 影像/語音/數據

  12. Introduction • Cable TV (HFC，Hybrid Fiber Coaxial) Diagram: http://www.cabledatacomnews.com/cmic/diagram.html

  13. Introduction • Cable TV Typically 500 to 5,000 homes cable headend home cable distribution network (simplified)

  14. Introduction • Cable TV

  15. Introduction • Cable TV

  16. AP AP Internet hub, switch or router BSS 1 BSS 2 Introduction • WLAN (WiFi)

  17. Mobile Switching Center Mobile Switching Center Public telephone network, and Internet wired network Introduction • Cellular Mobile Networks

  18. Introduction • WiMAX

  19. Introduction • Satellite Communication Networks

  20. Introduction • Classification of Computer Networks LAN(Local Area Networks) MAN(Metropolitan Area Networks) WAN(Wide Area Networks) SAN(Storage Area Networks)

  21. MAN MAN WAN Introduction • Classification of Computer Networks LAN LAN LAN LAN LAN LAN LAN LAN LAN LAN LAN • Applications of Computer Networks Email(Electronic Mail) E-Library BBS E-Commerce Financial ATM Video Conference Remote Medical SystemE-Learning

  22. 子網路 主機 交換機 傳輸線 傳輸線 Introduction • Network Structure:Components Terminal or Host: PC, Station Transmission Line: wired and wireless media, (circuit, channel, trunk) Switching Elements: switch, router Subnet: responsible for connecting hosts, usuallymaintained by ISP

  23. 1 2 4 6 3 5 Introduction • Network Topologies Star: ATM Ring:Token Ring, FDDI Bus:Ethernet Tree:100-VG-anyLAN Complete Connected Irregular

  24. Introduction • Network Types Broadcast Networks: (1) every host/station can receive the messages from a certain sender, e.g., Bus and Ring (2) usually used in small LAN (3) Ethernet, Token Bus, Token Ring, FDDI,…

  25. Introduction • Network Types (cont.) Point-to-Point Networks: (1) only the two established a connection can communicate each other (2) usually used in large scale MAN or WAN, e.g., ATM networks

  26. Introduction • Network Architecture: Why Protocol Hierarchy? Reduce complexity Provide standard interface Provide symmetric function for the same layers Provide predictable performance and be able to control the changes of SW/micro-code Provide standard language for designers, venders and managers to communicate Network Architecture: Protocol Definition Layer n on Host A carries on a conversation with Layer n on Host B. The rules used in this conversation are known as Layer n Protocol.

  27. 第 n 層協定 第n層 第n層 n / n-1 介面 n / n-1 介面 第 n-1 層協定 第n-1層 第n-1層 n-1 / n-2 介面 n-1 / n-2 介面 主機A 主機B Introduction • Network Architecture: Interface Between each pair of adjacent layers in the same Host there is an Interface

  28. Introduction • ISO OSI Reference Model The Physical Layer The Data Link Layer The Network Layer The Transport Layer The Session Layer The Presentation Layer The Application Layer

  29. receiver sender Actual data transmission path Application Application Presentation Presentation Presentation Protocol Session Session Encapsulation De-capsulation Transport Transport Network Network Data Link Data Link Physical Physical Introduction • ISO OSI Reference Model Message PH Data Data SH Data TH Data NH Data DT DH Bits Encapsulation and De-capsulation

  30. receiver sender Actual data transmission path Application Application Presentation Presentation Presentation Protocol Session Session Encapsulation De-capsulation Transport Transport Network Network Data Link Data Link Physical Physical Introduction • ISO OSI Reference Model Message PH Data Data SH Data TH Data NH Data DT DH Bits Encapsulation and De-capsulation

  31. receiver sender Actual data transmission path Application Application Presentation Presentation Presentation Protocol Session Session Encapsulation De-capsulation Transport Transport Network Network Data Link Data Link Physical Physical Introduction • ISO OSI Reference Model Message PH Data Data SH Data TH Data NH Data Bits Encapsulation and De-capsulation

  32. receiver sender Actual data transmission path Application Application Presentation Presentation Presentation Protocol Session Session Encapsulation De-capsulation Transport Transport Network Network Data Link Data Link Physical Physical Introduction • ISO OSI Reference Model Message PH Data Data SH Data TH Data Data Bits Encapsulation and De-capsulation

  33. receiver sender Actual data transmission path Application Application Presentation Presentation Presentation Protocol Session Session Encapsulation De-capsulation Transport Transport Network Network Data Link Data Link Physical Physical Introduction • ISO OSI Reference Model Message PH Data Data SH Data Data Data Bits Encapsulation and De-capsulation

  34. receiver sender Actual data transmission path Application Application Presentation Presentation Presentation Protocol Session Session Encapsulation De-capsulation Transport Transport Network Network Data Link Data Link Physical Physical Introduction • ISO OSI Reference Model Message PH Data Data Data Data Data Bits Encapsulation and De-capsulation

  35. receiver sender Actual data transmission path Application Application Presentation Presentation Presentation Protocol Session Session Encapsulation De-capsulation Transport Transport Network Network Data Link Data Link Physical Physical Introduction • ISO OSI Reference Model Message Data Data Data Data Data Bits Encapsulation and De-capsulation

  36. Application Message APDU Presentation PPDU Session SPDU Transport TPDU Data Header Network Packet Data Link Frame Data Trailer Header Physical Data Bit/Byte Stream Data Header Data Header Header Data Introduction • ISO OSI Reference Model Small size of message without fragmentation

  37. Application Presentation Message Session Transport Data Header Network Data Link Data Header Physical APDU Data Header PPDU Data Header SPDU Header Data Trailer TPDU Data Packet Frame Bit/Byte Stream Introduction • ISO OSI Reference Model Large size of message with fragmentation

  38. Introduction • The Physical Layer responsible for transmitting a series of bit or byte streams, can use electric or optical signal to carry “0” and “1”. open and close a physical connection transmitting a series of data bits management of physical layer • The Data Link Layer consists of two sub-layers, MAC(Medium Access Control) and LLC(Logical Link Control), data link establishment and release

  39. Introduction • The Data Link Layer (cont.) break upper layer data unit, Packet, into smaller data unit, Frame Sequence Control, Flow Control Error Detection, Error Control, Error Recovery • The Network Layer Routing and Relay Break upper layer data unit, TPDU, into smaller data unit, Packet Congestion Control, Billing and Accounting Subnet Control and Operation Reset service

  40. Introduction • The Transport Layer End-to-End Sequence Control, Error Control, and Flow Control Multiplexing function Mapping Transport address into Network address • The Session Layer Token management Synchronization management Login Management one-to-one mapping for Session connection and Transport connection

  41. Introduction • The Presentation Layer responsible for selection of syntax and semantics Data Compression, Encoding and Decoding Data Encryption and Decryption • The Application Layer File Transfer Virtual Terminal Handling Electronic Mail Remote Login

  42. Introduction • The DoD TCP/IP Model Network Access Layer: Internet Layer Transport/Host-to-Host Layer: Application/Process Layer: receives upper layer packets and then transmits them into physical media, and reverses the actions in the receiving end : packet format, packet transfer, routing, IP protocol end-to-end communication, error detection and control, error recovery, TCP protocol File Transfer, Email, Telnet,…

  43. Introduction • The DoD TCP/IP Model:Protocol Stack • Comparison of OSI and DoD TCP/IP Models OSI TCP/IP

  44. Application Application Presentation Presentation Session Session End-to-End Protocol Transport Transport Perfect Perfect Network Network Network Data Link Data Link Data Link Data Link OK OK OK Physical Physical Physical Physical Introduction • Layering Protocol:Operating Procedure Switch Router

  45. Introduction • Connection-Oriented and Connectionless Services Connection-Oriented Service:includes three phases (1) connection establishment phase (2) data transmission phase (3) connection release phase e.g. TCP • Connection-Oriented and Connectionless Services Connectionless Service: e.g., IP (1) no need of establishing connection (2) each data packet should have complete destination address

  46. Introduction • Network Terminologies Simplex Communication:data only travel in one direction, like one-way road, e.g., TV broadcast Half-Duplex Communication:data can travel in either direction, but not simultaneously, e.g., certain intercom Full-Duplex Communication:data can travel in both direction at once, e.g., telephone system Error Control:a mechanism about data retransmission or correction when error occurs

  47. Introduction • Network Terminologies Flow Control:a mechanism that controls the transmission and receiving rate in order to prevent data overflow and loss Acknowledgement Frame:a control frame used for the receiving end to inform the sender some information and status Bandwidth: bit per second (bps), kbps(103bps), Mbps(106bps), Gbps(109bps), Tbps(1012bps) Delay=transmission+queueing+propagation transmission delay = packet size/transmission rate propagation delay = path length/(2c/3) c: light speed queueing delay: queueing theory

More Related