Chapter I: Introduction
       The slides are adaptation of the  Overview:
          slides made available by the    what’s the Internet
          authors of the course’smain  
          textbook                        types of service
                                          ways of information transfer, routing, 
                                            performance, delays, loss
                                         --------------------------------------------
                                          protocol layers, service models
                                          access net, physical media
                                          backbones, NAPs, ISPs
                                          (history)
                                          quick look into ATM networks
      2                                                               1: Introduction
     What’s the Internet: “nuts and bolts” view
          PC         millions of connected                                  Mobile network
           server         computing devices: hosts =                                                  Global ISP
           wireless       end systems 
           laptop            running network apps
           cellular                                                          Home network
           handheld
                      communication links                                                         Regional ISP
                            fiber, copper, radio, 
                access 
                points          satellite                                            Institutional network
               wired        
               links            transmission rate = 
                                bandwidth
                      routers: forward packets 
          router           (chunks of data)
      1-3                                                                                                  Introduction
    What’s the Internet: “nuts and bolts” view
    protocols control sending, receiving         Mobile network
       of msgs                                                    Global ISP
         e.g., TCP, IP, HTTP, Skype,  Ethernet
    Internet: “network of networks”
         loosely hierarchical                    Home network
         public Internet versus private intranet                Regional ISP
    Internet standards
         RFC: Request for comments                    Institutional network
         IETF: Internet Engineering Task 
           Force
    1-4                                                               Introduction
   What’s the Internet: a service view
    communication infrastructure enables 
      distributed applications:
       Web, VoIP, email, games, e-
         commerce, file sharing
    communication services provided to 
      apps:
       reliable data delivery from source 
         to destination
       “best effort” (unreliable) data 
         delivery
   1-5                                               Introduction
     A closer look at network structure:
    network edge: 
       applications and hosts
    access networks, physical 
       media: wired, wireless 
       communication links 
     network core: 
        interconnected routers
        network of networks
   1-6                                                Introduction