TCP/IP

TCP在IP基础上提供了哪些功能?

1. 网络传输包丢失的问题; 2. 接收端如何按照顺序组装包的问题;3. 发送端与接收端速度不一致的问题.

• TCP adds extra header information to IP datagrams. This information allows recipients to
  tell the order in which datagrams were sent and do some fairly robust error-checking on
  the data.
• TCP extends IP by providing a way to acknowledge datagram receipt. That is, when data
  is received, it must be acknowledged. Otherwise, the sender must resend it. This also
  provides a way for recipients to tell senders that the data was received incorrectly.
• TCP defines buffering strategies. The computer receiving data over the network often has
  a fixed amount of space (its buffer) to hold data. If the sender sends information too
  quickly, the recipient may not be able to correctly handle all the information™ there might
  not be enough room in its buffer. The solution to this problem is simple: when using TCP,
  the sender must wait until the recipient tells the sender how much buffer space is
  available. Once it does, the sender may transmit only enough information to fill the buffer.
  It then must wait for the recipient to indicate that more buffer room is available.