network transport layer

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course notes for COMPUTER NETWORKING

  • two type of network app:

    • client and server programs are created by different programmer, follow the rules

    • .. same: client-server application

    • a transport-layer protocol provides logical communication between processesrunning on different hosts, a network-layer protocol provides logical communication between hosts

    • TCP congestion control prevents any one TCP connection from swamping the links and routers between communicating hosts with an excessive amount of traffic.
  • transport layer nultiplexing and demultiplexing
    • demultiplexing
      • delivering the data in a transport-layer segment to the correct socket
    • multiplexing
      • gathering data, encapsulation, pass segment to network layer
      • note that port number are examined by the transport
  • transport layer protocol
    • UDP
      • socket is identified by: dest IP + dest port num
        • diff source IP+port + same dest IP+port => same pocket in server
        • The TCP segment has 20 bytes of header overhead in every segment, whereas UDP has only 8 bytes of overhead.
    • TCP
      • socket is identified by: dest-IP+port num + source-IP+port
      • have two socket in one communication:
        • welcome socket: common use?
        • connection socket: for paricular client; close after server send reply
  • some abbr
    • RFC:
      • request for comments: some standard documents -
    • FTP:
    • HTTP:
      • use TCP protocol