TFTPD64 v4.00 "dropping" packets
Posted 22 July 2011 - 02:12 PM
Every once in a while ("often" may be more accurate) I am getting transfer failures where TFTPD has a timeout waiting for an ACK of a data packet it never sent. I am running TFTPD64 on a 64bit Win7 machine. I have tried running as admin and not. I have tried increasing the priority with no improvement.
I wrote the tftp client, and have experimented with different timeouts on both the server and client side (server > client, client < server, etc), but TFTPD never seems to attempt a retransmit. I have also tried never sending an ACK retransmit (sorcerer's apprentice problem), but still no retransmits from TFTPD.
I have wireshark packet capture (from the machine running TFTPD) and TFTPD log files, but I can't seem to find a way to attach them to this post. In the capture, my client receives and ACKs (repeatedly) packet 883, there is no packet 884 in the capture. In the log, TFTPD errors out on an ACK timeout for packet 884.
Also, often TFTPD does not send the the first data packet of a transfer and times out. I have captures and logs of this too.
Any tips/suggestions on what is going on would be greatly appreciated.
Posted 22 July 2011 - 10:59 PM
The other thing to check is that there is only one DHCP server on the network...
Is the file length a factor? what if you try a different file to transfer?
Posted 25 July 2011 - 03:49 PM
The issue is that wireshark is NOT showing the packet which (I am assuming based on the timeout error details) TFTPD thinks it sent.
Good idea about the hub, I will rerun the experiment.
The embedded target client uses a fixed IP, TFTPD's DHCP server is disabled and my PC gets it's IP from the corporate DHCP. Though it hasn't changed, I will set my PC up for fixed IP and rerun the experiment.
Length is a factor in that the larger files (~3.0MB) take longer to transfer and have more opportunity to drop a packet. There does not seem to be any repeatable factors in when the packet gets "dropped", even the smaller files can fail this way.
Do you have any incite as to why TFTPD would not retransmit the "dropped" packet?
Thanks again for your comments,
Posted 25 July 2011 - 03:56 PM
Posted 26 July 2011 - 04:10 PM
So, sorry for the noise on your forum, and thanks for a great tool!
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