RE : [lwip-users] what was the concensus on the tcp send problem

[Goldschmidt Simon]

>> If i send a block of data of say 4K the first block is sent but there
>> is a large delay sending the 2nd and 3rd block.
>
> Even with the patch (already check in the CVS HEAD)  from
> https://savannah.nongnu.org/bugs/?20506
> <https://savannah.nongnu.org/bugs/?20506>  ?

The patch raises the initial congestion window from 1mss to 2mss. The initial congestion window is responsible for this delay (tcp slow start algorithm). Until now, it was set to the conservative (and deprecated?) default of allowing only one segment of maximum size to be transmitted without receiving an ack, regardless of the window size it adverts or you set it to. Since the initial window size is now set to 2 mss and most other stacks will send an ack after receiving 2 frames (delayed ack), this should be done now. Simply upgrade to CVS HEAD if you can.

Simon