Design to use with Transceiver Toolkit

Hi,

I am trying to create a verilog design so that I can connect two SFP+ connectors on the same FPGA with an external cable and do BER tests on the loop using the transceiver toolkit. Can anyone help me get started with setting up a design to do this?

Also, I am having trouble with the pin assignments for the SFP+ ports. I am trying to assign one port as a transmitter by assigning the pin associated with SFPA_TX_n and assigning the other port as a receiver by assigning the pin associated with SFPB_RX_n. However, this leads to errors (ex. Error: The output pin SFP_TX assigned to HSSI Pin_XYZ has no fanin.). For each SFP port, there are multiple different pins, one of them being SFPA_MOD2_SDA for serial wire data. I am wondering if I should be using these pins instead, regardless of if I want to assign a port as input or output.