[lwip-users] Missed Ethernet Frame

[Colin Telfer]

Hi,

 

I have a problem where my embedded target running lwip 1.4.0 is occasional missing a single Ethernet frame, the last of a burst of frames.  I am capturing the TCP/IP traffic through a monitor port on a managed switch.  The only traffic flowing is point to point traffic between a Windows PC and the embedded target.  I see the “missing” frame on the wire, but the lwip stack is not ACKing this frame.  Sometime later a fast retransmission is triggered to recover the missing frame.

 

In the capture frame 100 is missed, with the ACK at 101 only including the sequence number for 99 and not 100.  We see the next duplicate ACK at 105.  Note the target (lwip) IP address is 192.168.0.101 and the Host (WinPC) is 192.168.0.200.

 

Any help would be greatly appreciated.  Are there any known bugs in 1.4.0 that could explain this behaviour?  Would moving to 1.4.1 help this specific failure case?

 

Thanks,

Colin

MissedFrame.pcapng
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