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Re: [lwip-users] Re-Transmission from PC is ignored due to sequence numb

From: address@hidden
Subject: Re: [lwip-users] Re-Transmission from PC is ignored due to sequence number
Date: Mon, 23 Apr 2018 20:29:45 +0200
User-agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.7.0

On 23.04.2018 17:08, Sergio R. Caprile wrote:
Take a look at frame #22, my Wireshark says "previous segment info not
captured" and its SEQ is 216.
Previous device frame in capture is #19 with SEQ 178 and len 21, which
is consistent with the PC ACKing 199 in frames #20/21.
There is a missing frame with SEQ 199 and len 17 that was supposedly
sent by lwIP.
Consistent with a Modbus response for 4 registers, as you ask on #20/21

Did you wait long enough ? Your capture file ends right there. Perhaps
lwIP timer is longer ?

lwIP should retransmit the lost packet after a time between some 100ms and some sconds. The capture is clearly not long enough. However, If the packet that gets retransmitted got lost before, it could be a bug that makes it get lost again...

Otherwise... We' found a bug in lwIP or in your driver/hardware.

I'll vote for the driver. At least if it's a hardware vendor driver ;-)


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