• State TI Thinks Resolved
  • Locked Locked
  • Replies 2 replies
  • Answers 1 answer
  • Subscribers 33 subscribers
  • Views 1814 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

DP83867IR: Packet loss, how to run far end loop back test

Ken lucas
Intellectual 360 points
Part Number: DP83867IR

Hello,

We are bringing up a custom board with a DP83867IR connected to a ZYNQ FPGA and are having packet loss issues. The problem exists 

regardless of speed i.e. 10MB/100MB or1000MB. At 1000MB small packets under 32 bytes pass a ping test without issue, but larger packet sizes fail. We believe 

we have configured the DP83867 correctly for loopback but we are not sure what IP address we should ping. We allow the device to auto negotiate,

so our assumption is that we will use the IP address configured during auto negotiation, is this correct? Can some one explain how the far end loop 

works. We read the section in the troubleshooting guide, but it would seem like a ping to loopbacked phy would not have an IP address.

Thanks,

Ken

  • 0
    TI__Mastermind 18425 points

    Hi Ken,

    Far end loopback testing is when one PHY sends data to the link partner over ethernet cable and the link partner loops the data back to the sender. In order to establish a loopback test, you will need to connect 2 DP83867 units to each other using a ethernet  cat5e cable. Then the device that you want to test (DUT) should be the sender and the other device should be in reverse loopback mode via register 0x16. Start transmitting data through the DUT and observe the data coming back to check if it has errors.

    Ping is generally handled at a higher level in the application. When reverse loopback is enabled on a PHY, the PHY will forward data to its own MAC. It will just loopback the data to the sender. In this case, IP address would not come into picture because the receiver side MAC never gets the data. For reverse loopback testing, it is recommended to just use raw ethernet data if possible and check for error on the DUT side.

    -Regards

    Aniruddha

  • 0 in reply to Aniruddha Khadye
    Intellectual 360 points

    Thanks for the reply. Is there a document that details how to perform this test using a EVM as the second DP83867 device?

    Do we need to use any special utilities?

    Thanks,

    Ken