广播和多播仅应用于UDP，它们对需将报文同时传往多个接收者的应用来说十分重要。TCP是一个面向连接的协议，它意味着分别运行于两主机（由IP地址确定）内的两进程（由端口号确定）间存在一条连接。-broadcast and multicast only used UDP. they need to be reported - the same time as the recipient of several important applications. TCP is a connection-or