Why does the Stratix® 10 25G Ethernet IP core receive random erroneous packets in open ended condition?

In rare cases, the Stratix® 10 25G Ethernet IP core may still receive random erroneous packets when operating in open ended condition, i.e. there is no fiber or QSFP28 module connected.

A workaround for this problem is to edit the SYNOPT_STRICT_SOP parameter in the top level IP wrapper file to 1.

This workaround is only available for designs with Preamble Pass-Through feature disabled.

Locate the 25G Ethernet IP variant wrapper file at /synth/<file_name>.v.

At the instantiation of the version specific 25G Ethernet IP, change the SYNOPT_STRICT_SOP parameter setting from (0) to (1).

Do not regenerate the 25G Ethernet IP core. Compile your design.

Example design IP variant file at /synth/ex_25g.v:

ex_25g_alt_e25s10_191_dyjat6a #(

    .SYNOPT_READY_LATENCY          (0),

    .SYNOPT_CORE_VAR                      (0),

    .SYNOPT_KHZ_REF_EN                  (0),

    .SYNOPT_RSFEC                              (0),

    .SYNOPT_DIV40                               (1),

    .SYNOPT_LINK_FAULT                    (0),

    .SYNOPT_STRICT_SOP                  (1),

    .SYNOPT_PREAMBLE_PASS          (0),

Please note that you may observe junk data on the 64-bit l1_rx_data bus. The l1_rx_valid should be used as an indicator to accept or ignore the data.

This problem is scheduled to be fixed in a future release of the Quartus® Prime Pro Edition Software.