Overview (kỹ THUẬT TRUYỀN số LIỆU SLIDE)

Overview of Data Communication and Computer Networks Outline  Data Communication Overview  Definition  Components  Protocols and standards  Network Overview  Connectivity  Categories  Internetworks Motivations  Efficient way to share resources  Cost – less expensive  Accessibility – easier  Efficient way to exchange information  Time – faster  Size – bigger  Correctness – more accurate Data Communication: Definition  Data Communication: Transfer Transferof ofdata datafrom fromone onedevice deviceto toanother anothervia via some someform formof oftransmission transmissionmedium medium Data Communication Hi, Hi, how how are are you? you? Hi, how are you? Hi, how are you? Computer 01010001 Click to edit Master text styles 01010001 Second level Third level Fourth level User Communications Characteristics  Effectiveness of a data communications system depends on characteristics:  Delivery: correct destination, user…  Accuracy: accurate data reception at destination  Timeliness: same order without significant delay  real-time transmission  Jitter: variation in the packet arrival time Components in Communication Message Hi, how are you? Protocol Sender Receiver Medium Data Representation  Numbers  8/16/32 bit integers  floating point 150  Text  ASCII, Unicode  Images 255  Bit patterns, Graphics formats JPG/GIF/etc  Audio → Samples of continuous signal  Video → Sequence of bitmap images Protocols and Standards  Protocol  A set of rules governing data communications  Syntax: format of data block  Semantics: meaning of each section  Timing: speed and sequencing  Standards  De facto (in practice) standards → not approved but widely adopted  De jure (in law) standards → approved by an organization 10 Bus Topology  Pros:  Little cabling  Easy to install  Cons:  Difficult to modify  Difficult to isolate fault  Break in the bus cable stops all transmission 31 Ring Topology C D B A 32 Ring Topology 33 Ring Topology  Pros:  Easy to install  Easy to identify fault  Cons:  Delay in large ring  Break in the ring stops all transmission 34 Hybrid Topologies 35 Network Categories  Local Area Network (LAN)  Wide Area Network (WAN)  Metropolitan Area Network (MAN) 36 Local Area Networks  Network in a single office, building, or campus 37 Wide Area Networks  Network providing long-distance communication over a country, a continent, or the whole world 38 Metropolitan Area Networks  Network extended over an entire city Bangkhen Kampangsaen 40 Switching  Dedicated circuits  Circuit switching  Telephone switches establish circuits for communication  Packet switching  Data are put into packets telephon e  Each stamped with switch source and destination addresses  Routers know where to forward packets Packe Route t r 41 Network of Networks Company B Company A Network Interface Card (NIC) Company C Company D 42 Internetworking  How to allow devices from different standards to communicate  Gateways/routers – devices capable of communicating in several standards  These become "network of networks" 43 Internetworks  Two or more networks connected become an internetwork, or internet Network1 Network2 Gateway Network3  Example: The Internet 44 The Internet  The largest internetwork (network of networks) in the world  Devices communicating with TCP/IP protocol suite Stanford U of Utah UC Santa Barbara UCLA 45 Summary  Data communication  Protocols and standards  Computer networks  Topologies  LAN/MAN/WAN  Internetworks (networks of networks) 46 ...Outline  Data Communication Overview  Definition  Components  Protocols and standards  Network Overview  Connectivity  Categories  Internetworks Motivations