WORKAROUND: You will find the checksum right If you do capture inline by a switch mirror. NOTE & WORKAROUND2: Spirent TestCenter (if available) can be used as a Network TAP, and this controller can capture Packets at a lower level with the FCS field in place (without) offloading this function to the Network Driver on the Operating System. if need assistance for setting up STC as network TAP, please create a new support ticket for the STC Support Team.