[lwip-users] TCP [TCP Window Update]

[Alain Mouette]

Hi, I am getting quite a lot of these in WireShark:

TCP [TCP Window Update]

0) I am using the socket interface :)
1) lwip sends a 15 byte packet to the server
2) the server responds an 11 byte packet, with ACK
3) lwip sends an ACK with a reduced window, from 2048 to 2037, delay is 
between 5 and 66ms
4) lwip sends an extra ACK with the full window size, delay is around 250ms.
5) next packet is sent usualy many minutes later...

What I can understand that is happening is this: I take a little too 
long to read the received data. I am using select to poll for data, with 
1ms delay, but it is with FreeRTOS and so it might take a little longer 
sometimes...

My question is: is there a way to delay that ack so that it only goes 
after I read the data? Or store it somewhere (like buffers)?

This is to be with GPRS and I am getting over 20% extra trafic just for 
that :(

Thanks,
Alain