Can you use the C:\ti\pdk_C6670_1_1_2_6\packages\ti\drv\exampleProjects\PA_simpleExample_exampleProject or PA_emacExample_exampleProject as the starting point? Those two projects tried to send out some packets and loop them back and verify. You can change the code as no loopback and test between 2 6670 EVMs.
Regards, Eric