wTCP本身已经确保传输的成功性。
HTTP The Definitive Guide
4.2.4 Delayed Acknowledgments
Because the Internet itself does not guarantee reliable packet delivery (Internet routers are free to
destroy packets at will if they are overloaded), TCP implements its own acknowledgment scheme to
guarantee successful data delivery.
Each TCP segment gets a sequence number and a data-integrity checksum. The receiver of each
segment returns small acknowledgment packets back to the sender when segments have been received
intact. If a sender does not receive an acknowledgment within a specified window of time, the sender
concludes the packet was destroyed or corrupted and resends the data.
TCP implements its own acknowledgment scheme to guarantee successful data delivery
原文：http://www.cnblogs.com/yuanjiangw/p/6360343.html