On Tue, 2010-03-02 at 17:19 +0700, PHAM ANH THIEN wrote: > hi Kieran, > > So you mean the current lwip stack configured sliding window 2 packets > in window and fixed it & can not change it?
No. There are two parts of TCP that you are putting together and confusing: 1) A sliding window where the sender can send to use up all the window, and the receiver sends ACKs to update it bit by bit as more buffer space is available. The size of this window is configured by setting TCP_WND on the receiver, but the sender can also be limited by other things (e.g. congestion, its send buffer, the application, and so on) and so not send immediately there is space in the receiver's window 2) The delayed ACK mechanism. This makes TCP more efficient by not sending as many ACKs, at the expense of not updating the sender as often. It sends at least one ACK for every second packet. Not all ACKs will update the window and allow it to slide so the sender can send some more: this depends on whether the application has read the packets when the ACK is sent. Kieran _______________________________________________ lwip-users mailing list lwip-users@nongnu.org http://lists.nongnu.org/mailman/listinfo/lwip-users
