Transmission Control Protocol provides a reliable ordered byte-stream service between its endpoints, using sequencing, acknowledgements and retransmission. Receipt by that transport does not establish that a receiving application has durably stored the data or completed a user operation.[ref]
A zero-window probe solicits a current receive window advertisement when a sender has been stopped by a zero window. Repeated probes recover from a lost reopening acknowledgement.
The persist timer schedules repeated zero-window probes, preventing an exchange from waiting forever after a window-reopening message is lost.
Silly window syndrome is inefficient transmission in tiny TCP segments, arising through small writes or small increments of advertised receiving space. Sender and receiver measures address different causes.
Nagle's algorithm coalesces small writes while data are unacknowledged, permitting another send when a full TCP segment can be formed or the outstanding data have been acknowledged. It reduces tiny transmissions but can add delay.
A TCP segment contains a TCP header and zero or more data bytes. The header carries sequencing, acknowledgement and receive window information.
