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qwitza's avatar
qwitza
Icon for Occasional Contributor rankOccasional Contributor
3 years ago

Cyclone V rmgii KSZ9031RNX terrasic de10-nano => tcp retransmission

hello, we use the terasic de10-nano board and transferring a huge amount of data bidirectional. The data is copied with scp. Copy data from the pc => de10-nano board is okay. Copy data from the de1...
Kshitij_Intel's avatar
Kshitij_Intel
Icon for Frequent Contributor rankFrequent Contributor
3 years ago

Hi,


In a TCP/IP Client-Server Model arch, TCP retransmission errors can happen ONLY when the transmitting end does not receive TCP-ACK from the receiving end.


Few possibilities of NOT receiving TCP-ACK are:


  1. The receiving end sent back TCP-ACK is LOST in transit.
  2. The transmitting end TCP-DATA is LOST and it did not reach the receiving end at all.


it's normal to see TCP retransmission, but a high number can impact traffic flow.


Usually it's cabling that it's not so good, and causes packet drops.


Check for errors along the traffic path.


Also, you could issue an extended ping see if packets are lost... also do a traceroute and see if there is unusually large delay at a particular hop.


If packets are lost on the ping on and off it could be a load balancing issue. If you know there is load balancing somewhere in your network, one path works and one path doesn't work causing some packets to be lost and some to not be lost.


Also, a lot of retransmissions could be the result of port buffer overflow, and either Tx or Rx or both are dropping packets.


Hope these inputs will resolve your issue.


Thank you

Kshitij Goel


  • qwitza's avatar
    qwitza
    Icon for Occasional Contributor rankOccasional Contributor
    3 years ago

    Hi,

    thanks you a lot for the answer.

    the board is direct connected at the computer, no switch etc, only a 3m cat6 cable.

    i check different boards,

    - de10-nano and our

    - custom board

    but on both boards sometimes we get an retransmission error transfer an 1gb file, i think this is "usal".

    but i am confused about the skew timing, i open an new thread about that issue.

    thanks