I have recently just watched an excellent Cisco Live video on UCS performance troubleshooting which demonstrated how to trace network traffic within Cisco UCS. The speaker made a comment though, in order to determine which NIF is used by a VIF when port-channels are used between the FEX and FI there are different commands to run. Have to review the hash result or something he said. Unfortunately he never went into what these commands were.
So when we have veths pinned to port-channels instead of HIFs and NIFs, what commands will show which path is being used?