This option controls how the
SO_SNDBUF limit is applied to TCP sockets. In the default mode the limit applies to the size of the send queue and retransmit queue combined. When this option is set to
0 the limit applies to the send queue only.
When this option is set to
2, the SNDBUF size is automatically adjusted for each
TCP socket to match the window advertised by the peer (limited by EF_TCP_SOCKBUF_MAX_FRACTION). If the application sets
SO_SNDBUF explicitly then automatic adjustment is not used for that
socket. The limit is applied to the size of the send queue and retransmit queue
combined. You might also want to set EF_TCP_RCVBUF_MODE to give automatic adjustment of RCVBUF.