When the client issues connect, the tcp_output function is called at the protocol layer, which outputs the SYN packet onto the interface.

当客户端发布connect时，在协议层调用tcp _ out put函数，将SY n包输出到接口。

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Transport Layer protocols, such as the Transmission Control Protocol (TCP), the User Datagram Protocol (UDP), specify a source and destination port number in their packet headers.

传输层协议，诸如传输控制协议（TCP），用户数据报协议（UDP）， 会在它们的头部指定一个资源和目的地的端口号。

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In wireless packet networks, because we need radio to receive or send data, so a basic problem is how to attach radio protocol to DTE's data link layer and assure communication running well.

无线分组网中，由于需要利用电台收发数据，于是在DTE的数据链路层中加入电台协议，保证DTE与电台的通信正常进行是需要解决的基本问题。

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