Roadmap
        •  What’s the Internet
            – Nuts&bolts view
            – Service view 
            – Distinction between network edge and network core 
        •  Layers of abstraction, protocols
        •  ISO/OSI & Internet layer structure
        •  Data communication through layers: physical and logical 
           view
    Marina Papatriantafilou –  Introduction to computer communication      3a-2
     the Internet: “nuts and bolts” view (1)
                    •    millions of connected 
          PC             computing devices: hosts                            Mobile network
           server        = end systems                                                                Global ISP
           wireless        –  running network apps
           laptop
           cellular                                                          Home network
           handheld
                          •    communication links                                                 Regional ISP
                                 •   fiber, copper, radio, 
                access               satellite
                points           •   transmission rate =                             Institutional network
               wired                 bandwidth
               links
                          •    routers: forward packets 
          router               (chunks of data)
                                                                                Introduction                                  1-3
      Marina Papatriantafilou –  Introduction to computer communication 
     “Fun” internet appliances
                                      Web-enabled toaster +
                                      weather forecaster
       IP picture frame
       http://www.ceiva.com/
                                             Tweet-a-watt: 
                                             monitor energy use
                    Slingbox: watch,
                    control cable TV remotely
        Internet 
        refrigerator                    Internet phones
                                      Introduction        1-4
   Marina Papatriantafilou –  Introduction to computer communication 
   the Internet: “nuts and bolts” view (2)
   • protocols control sending,     Mobile network
     receiving of msgs                         Global ISP
      – e.g., TCP, IP, HTTP, Skype,  
        Ethernet
   • Internet: “network of          Home network
     networks”                                Regional ISP
      – loosely hierarchical
                                       Institutional network
                                      Introduction        1-5
   Marina Papatriantafilou –  Introduction to computer communication 
    the Internet: service view
    •  communication infrastructure 
       enables distributed 
       applications:
        – Web, VoIP, email, games, e-
          commerce, file sharing
    •  communication services 
       provided to apps:
        – Reliable, in-order data 
          delivery from source to 
          destination
        – “best effort” (unreliable) 
          data delivery
    Marina Papatriantafilou –  Introduction to computer communication      1-6