TCP/IP ?
          TCP/IP ?
           TCP = Transmission Control Protocol
            TCP = Transmission Control Protocol
           IP = Internet Protocol
            IP = Internet Protocol
           Almost always includes other protocols:
            Almost always includes other protocols:
             – UDP, User (Unreliable) Datagram
                UDP, User (Unreliable) Datagram
             – ICMP, Internet Control Message
                ICMP, Internet Control Message
             – ARP, Address Resolution
                ARP, Address Resolution
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          Mateti, TCP/IP Refresher             
          Mateti, TCP/IP Refresher             
          What’s a Protocol?
          What’s a Protocol?
           An agreed upon convention for 
            An agreed upon convention for 
            communication.
            communication.
           Protocols must be formally 
            Protocols must be formally 
            defined and unambiguous
            defined and unambiguous
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          Mateti, TCP/IP Refresher             
          Mateti, TCP/IP Refresher             
             Layers
             Layers
                                          TCP
                                             
                             UDP             
                                                      ICMP         other
                           IP layer     IP layer     IP layer    IP layer
  
              Physical     Physical     Physical    Physical     Physical      Physical
             The relative heights indicate the level of functionality. 
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             Mateti, TCP/IP Refresher             
             Mateti, TCP/IP Refresher             
           Unix is a Layered 
           Unix is a Layered 
           System
           System
                            Applications
                              Libraries
                            System Calls
                                Kernel
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          Mateti, TCP/IP Refresher             
          Mateti, TCP/IP Refresher             
          Layers
          Layers
           The routines/methods of Layer N 
            The routines/methods of Layer N 
            will not call Layer N+1.
            will not call Layer N+1.
           The routines/methods of Layer N 
            The routines/methods of Layer N 
            typically do call the same layer 
            typically do call the same layer 
            methods. 
            methods. 
           The routines/methods of Layer N 
            The routines/methods of Layer N 
            typically do call Layer N-1 
            typically do call Layer N-1 
            methods.
            methods.
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          Mateti, TCP/IP Refresher             
          Mateti, TCP/IP Refresher