[lwip-users] Retransmission problems on server sockets

[Luca Ottaviano]

Hi list,
I'm using lwIP 1.3.2 but I hope someone can give me a suggestion.

I'm having a few problems in case of lost packets, which don't seem to
be retransmitted. My test case is a simple echo server using the sockets
API, sample code is attached.
The server resides on an embedded device on which runs lwIP, the client
is a netcat instance connecting from a PC.

First I establish a connection with the device, then I activate a
firewall on the PC, dropping all incoming packets from the device (to
simulate lost packets). After a few seconds I disable the firewall again
to let the communication complete.
In this test case, strings sent from the PC they are never echoed
because the device doesn't realize that the PC has not ACKed the bytes
in the dropped packet.
See attached tcpdump for an example session.

The problem does not show up if I use a client socket, that is if I
connect from the device to an echo server on the PC. In this case,
packets are retransmitted correctly.

Am I doing something wrong? Where should I start looking at?
Thanks!
-- 
Luca Ottaviano - address@hidden
Develer S.r.l. - http://www.develer.com/
.hardware .software .innovation
Tel.: +39 055 3986627 - ext.: 218

retransmission-log.pcap
Description: Binary data

main.c
Description: Text Data

cfg_lwip.h
Description: Text Data