RFC2544 testing will not pass on when connected to Cisco Nexus switch, has anyone else had this issue? We have connected to E5 on same card on Nexus and get one way traffic. Is there some special protocol that is used to establish if there is a loopback set on far end device? Cisco is not sure why it will not work. We can move same two test E5-308 to any other cisco device in network and run test okay. Normal customer traffic will pass without any problem.