[lwip-users] [lwip] Some lwIP findings : ACKs and slow start

[Chris Borrelli]

Does anyone know why lwIP sends out ACK segs without data in the payload.  I
am using an echo server for some tests, and lwIP sends 2x the number of
packets it should because it sends empty ACKs...

Another thing I noticed is that lwIP echo server and a Windows client have
trouble sending large sized segments. The size of the packets ramps up from
100 bytes to 500 bytes... then it goes back down to 100 bytes..  here is the
situation:

my MSS = 536.

PC: sends 100 byte segment
lwIP: ACK
lwIP: echos 100 byte segment
PC: sends 200 byte segment, ACK
lwIP: ACK
lwIP: echos 200 byte segment