Forum Discussion

Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
20 years ago

Webserver/LWIP problem

hi guys, ive got a tough one here

im using the altera provided webserver example to pump over data, a 8 meg html file to be exact, and most of the time things go well

i also tweaked the TCP settings of the LWIP stack a bit, i changed the packter buffers from 16 to 4, and changed the TCP send window to 17520, which is the default on the connecting windows PC, for optimal speed, this gave me an improvement of about one second, from 8.1 to 7.1 transfer time

however, with these settings, sometimes the server will crash, the last two packets sent over the network are TCP window updates from the PC to the server, first switching the window to 2596, then back up to 17520, the end result is that the webserver will simply stop sending data, untill the next web page is requested

does anyone know why the server cant handle the sudden change in TCP window? altering any settings on the windows PC is no real option

1 Reply

  • Altera_Forum's avatar
    Altera_Forum
    Icon for Honored Contributor rankHonored Contributor
    20 years ago

    well i seem to have solved the problem at least partially myself

    in the TCP_in file in the LWIP source, i disabled the piece of code in the ACK handling routine where it accepts the TCP window update value and puts the value into code, this stopped the random crashing on two concurrent window updates

    however, i think that by doing this i disabled a part of TCP flow controll, so performance might not benefit, the normal numbers ive seen are similar to how fast it was with the code in original form, but it still isnt recommendable i think to try this

    if i have anymore news ill post here to log the problem/solution for anyone who happens upon the same troubles