Hello,
I'm not that pro in TCP/IP communication but it seems that only 1 packet
is lost.
When A retransmit the missing one plus some more data, your board is
finally able to rebuild the stream and continue acknowledging all
received data. A does not retransmit the last 18 bytes because they have
been successfully received & acknowledged.
Is IP_REASSEMBLY activated and how big is your IP_REASS_MAX_PBUFS ?
Except for the part where you lose a packet, the flow does not seems to
me that buggy.
--
Le 23/08/2013 22:30, Rodrigo Garbi a écrit :
Hi!
I'm working with FreeRTOS v7.0.1 and LwIP 1.4.0 and I'm facing the
following problem:
Device A and B transmit data every 40 ms to my board (where I'm
running LwIP) and once in a while I can notice some data from device A
is being missed.
So I did some research with CommView and found that:
1) Device A sends data (9 bytes length) to my board and get correct
ACK from it:
Sequence: 0x13D5388C (332740748)
Acknowledgement: 0x00001A57 (6743)
Response from my board:
Sequence: 0x00001A57 (6743)
Acknowledgement: 0x13D53895 (332740757)
2) Device A send 9-bytes data to my board, but this won´t ACK:
Sequence: 0x13D5389E (332740766)
Acknowledgement: 0x00001A57 (6743)
Sequence: 0x00001A57 (6743)
Acknowledgement: 0x13D5389E (332740766)
3)Device A does not care about it (maybe because data is already in
ethernet transceiver buffer) and sends a new data (9-bytes); my board
will not ACK it:
Sequence: 0x13D538A7 (332740775)
Acknowledgement: 0x00001A57 (6743)
Sequence: 0x00001A57 (6743)
Acknowledgement: 0x13D5389E (332740766)
4)Same as 3
Sequence: 0x13D538B0 (332740784)
Acknowledgement: 0x00001A57 (6743)
Sequence: 0x00001A57 (6743)
Acknowledgement: 0x13D5389E (332740766)
5) Same as 3
Sequence: 0x13D538B9 (332740793)
Acknowledgement: 0x00001A57 (6743)
Sequence: 0x00001A57 (6743)
Acknowledgement: 0x13D5389E (332740766)
6) Finally, device A is aware of the problem and retransmits data, but
instead of transmitting 36 bytes (9 x 4), only transmits 18 bytes
Sequence: 0x13D5389E (332740766)
Acknowledgement: 0x00001A57 (6743)
Data length: 0x12 (18)
And my board running Lwip 1.4.0 will acknowledge 36 bytes instead of 18:
Sequence: 0x00001A57 (6743)
Acknowledgement: 0x13D538C2 (332740802)
So device A won´t transmit last two 9-bytes packets, and they will be
lost!
Anyone can help me with this? Is it a bug in LwIP or what is happening?
Thank you!
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