[lwip-devel] [bug #20640] Request getting lost/unanswered in lwip stack

[Kieran Mansley]

Follow-up Comment #1, bug #20640 (project lwip):

Fundamentally TCP is not a real-time protocol and will not be able to provide
the sort of timing guarantees you're hoping for.  Any packet loss in the
network will mean things take longer than 200ms to complete.

Which IP address is the PC and which is the lwIP board, and at which end did
you get the packet capture (I'm assuming PC)?

Looking at your trace I see a lot of RST packets.  Any idea why the FINs
aren't getting correctly ACKed and instead RST?

I suspect that this may be the cause of some of your problems - if
connections remain active because they haven't been properly closed, it may be
that new connections can't be properly established.  Just a guess though as I
can't spare enough time at the moment to look in detail.

Finally, if the PC is issuing these requests every 200ms, and the capture is
made on the PC, why don't they appear in the trace every 200ms?  That suggests
that the PC is in fact no making requests at the frequency you want.  Perhaps
it is waiting for the response to earlier ones?

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