《计算机网络和 与因特网》课件第五章可靠传输服务.ppt

works and s
《计算机网络与因特网》课件
林坤辉
PART III working
Chapter 5 TCP: Reliable Transport Service
T C P:可靠传输服务
The Need for Reliable Transoprt可靠传输的必要性
The application write data to the device, but does not need to verity that data arrives intact.
Instead, the application relies on the puter system to ensure reliable transfer; the system guarantees that data will not be lost, duplicated, or delivered out of order.
The Transmission Control Protocol传输控制协议
TCP is the transport level protocol.
TCP provides reliable transport service.
Most applications are built to use TCP.
TCP provides pletely reliable(no data duplication or loss), connection-oriented, full-duplex stream transport service.
The Service TCP Provides To ApplicationsTCP为应用提供的服务
Connection orientation
Point-To-plete reliability
Full munication
Stream interface
Reliable connection startup
Graceful connection shutdown
Achieving Reliability实现可靠性
The major problems are:
Unreliable delivery by the munication system.
Computer reboot.
Packet Loss and Retransmission包丢失与重发
By implementing a retransmission scheme.
IP数据报文丢失的处理
目标端
TCP程序对于每一个收到的IP数据报文,向源端发送一个响应报文作为确认
源端
TCP程序重传丢失的IP报文
重传条件:一定时间内没有收到响应报文
重传时间:根据一定算法确定的超时等待时间