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Hello,
Sorry for asking a non-Keil related question. I am using lwIP on a LPC2478 to quickly send a lot of data to a server. When I connect the product to a VPN located far away (New Zealand...) often some characters are replaced by lwIP device drive due to some race condition that I haven't identified yet (that does not happen when data is sent from less distant locations). I have seen from Wireshark logs that the corrupted frames are marked as having a bad checksum - that is no surprise - but the receiving end never kicks in the TCP re-transmission mechanism (it rather acknowledges the corrupt frames!). Any idea what is going on here?
"but the receiving end never kicks in the TCP re-transmission mechanism"
From the point of view of the TCP stack, it is not the responsibility of the receiver to 'kick' the retransmission. It should ignore the bad packet and the sender (because it sees no acknowledge) should retransmit the data.
"(it rather acknowledges the corrupt frames!)."
That really goes with my last point. If the receiver is returning an acknowledgement, then the sender should assume correct reception has occured.
I think you need to check some details - Especially determine why the receiver is returning an acknowledge.
DJR
OK I get it, thanks.
Or the ZWP packets are incorrectly handled at the sender, that is LwIP I guess.