TCPIP_Chapter9UserDatagramProtocol(UDP)讲解.ppt

网络工程系 * 电子科大通信学院 * Well-known port number的分配算法： 全局指派 动态查询 TCP/IP Protocol Suite TCP/IP Protocol Suite TCP/IP协议原理 吴凡 通信与信息工程学院网络工程系 E-mail: wufan@ Phone:(O) * TCP/IP Protocol Suite * Transport Layer Protocol Transport Layer protocol: To serve as the intermediary between the application programs and the network operations Responsibilities To create a process-to-process communication To provide a control mechanism at the transport layer flow control error control To provide a connection mechanism for the processes Data stream 2 Protocols for transport layer Transmission Control Protocol，TCP User Datagram Protocol，UDP * TCP/IP Protocol Suite * Chapter 9 UDP Process-to-process communication User datagram Checksum UDP operation Use of UDP UDP package * TCP/IP Protocol Suite * Process-to-Process Comm. Internet 进程 Process 进程 Process Domain of IP protocol Domain of transport protocols IP地址 协议端口（port） 端点（endpoint） ＋ * TCP/IP Protocol Suite * IP entity Transport Layerprotocol entity Port Numbers 21 2000 ( 21 ) ( 23 ) ( 80 ) Process1 Process2 Process3 80 3450 23 6490 IP Address * TCP/IP Protocol Suite * Process-to-Process Communication UDP负责将IP数据报交付给适当的进程 Process（进程）: a running application program A computer can run several processes at the same time C/S application model Client: a process on the local host which needs services Sever: a process on the remote host which provides the services For Process-to-Process Communication, must define the: Local host (IP), local process (Port Number) Remote host (IP), remote process (Port Number) * TCP/IP Protocol Suite * Port Numbers VS. C/S Port number: to define the processes Ephemeral port number（短暂端口号）: can be chosen randomly by the client process Well-known port number（熟知端口号）: is universal port number for server process 传输协议 Data 13 52000 Data 13 52000 传输协议 13 52000 Client Server … … 多目标 并发通信 Well-known ports used with UDP * TCP/IP Protocol Suite * * TCP/IP Protocol Suite * IP Address Port Number 13 52001 13 520