TFTP Server does not retransmit packets if it does not receive acknowledgement within the negotiated timeout

We noticed TFTP Server does not retransmit packets if it does not receive acknowledgement within the negotiated time

In our case - In Packet 89 the TFTP client requests o Blocksize: 1432 o Timeout: 1 - Those values are acknowledged by the server in packet 90

In packet 1515 contains datablock 472 which is acknowledged in Packet 1516
The next datablock (473) is sent by the server in packet 1518 but it seems it is not received by the TFTP client (this might happen for many reasons in TFTP)
The client signals this by retransmitting the acknowledgement of block 472
Since the client receives no retransmission of block 473 after the agreed timeout of 1 second, it retransmits the acknowledgement of block 472
This repeats six times
The server finally sends the retransmission after 8 seconds -- clearly breaking the agreed timeout of 1 second, but still in time to continue the filetransfer
The same thing then happens again from packet 2472 (datablock 753) onward
Only this time the server does not retransmit the missed data block (754) at all
So after 10 retransmissions of the acknowledgement for block 753 and no retransmission of block 754 from the server the client eventually aborts the transmission.

So the reason for the failed transfer seems to be:

The server does not retransmit missed datablocks after the agreed timeout of 1 second (or at all).

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