TCP/IP提供了无连接的传输层协议：UDP(User Datagram Protocol，即用户数据报协

议)。UDP 与 TCP 有很大的区别，因为无连接的 socket 编程与面向连接的 socket 编程也有很

大的差异。由于不用建立连接，因此每个发送个接收的数据报都包含了发送方和接收方的地

址信息。 -TCP/IP provides a connectionless transport layer protocol: UDP (User Datagram Protocol, that is, User Datagram Protocol). UDP and TCP are very different, because there was no connection socket programming and connection-oriented socket programming, there are big differences. Because no connection is established, each sending a received packet contains the sender and recipient address information.