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I am experiencing a problem that has me
very confused and I wonder if anybody has seen this or could
suggest an idea.
My embedded device runs lwip and has been
working great with IPv4. It uses a WiFi module to handle raw
Ethernet packets that I send it and I get raw Ethernet from
it. I updated to latest lwip to add IPv6 support. I was able
to add it and it seemed to work great. That is, with my
windows XP machine (IP6 enabled) I could communicate fine with
the IP6 embedded device. But someone else in my company then
tried it with their Windows 7 machine and couldn’t connect.
Since then we have tried many different machines – XP, Vista,
Win7. Only the Windows 7 machines have problems.
A strange thing is that they can ping the
embedded device fine but can’t open a TCP connection. I have
done many Wireshark captures and can see that the Win7 PC
sends a SYN and the embedded device responds with a SYN,ACK.
But then the PC acts as though it never received the SYN,ACK
because it just times out and sends the SYN again. I have
compared Wireshark captures from PCs that are able to connect
and PCs that are not able to connect and those SYN and SYN,ACK
packets look identical except for IP and MAC addresses.
I thought maybe it’s the WiFi routers but
they are just bridged to pass everything through and it does
seem that they are routing the packets OK as the PC wireshark
logs show – the SYN,ACK from the embedded device gets to the
PC but the PC never responds with the ACK.
Is there some special thing to configure
windows 7 to work with IP6 or something I am missing? Any