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The local port (it can be shown by the
–show_links
command):
mstlink –d <device> --port_type PCIE –port
1
–margin –measure_time
10
Rx-to-Tx Loopback Mode Activation
This capability enables Rx-to-Tx remote loopback mode.
Prerequisite
The port should be disabled and configured with Force mode [Disable the Auto-negotiation]
Remote loopback is supported for 25G/50G per lane speed
If the NIC has 2 ports, both ports should be configured with the same speed
To enable Rx-to-Tx remote loopback mode:
Disable the port.
mstlink -d /dev/mst/mt4123_pciconf0 –port_state DN
Configure the link mode to Force [Disable the Auto-negotiation].
mstlink -d /dev/mst/mt4123_pciconf0 --speeds 100G --link_mode_force
Configure loopback with remote loopback [RM].
mstlink -d /dev/mst/mt4123_pciconf0 –loopback RM
Enable the port.
mstlink -d /dev/mst/mt4123_pciconf0 –port_state UP
To return to the normal link operation:
Disable the port.
mstlink -d /dev/mst/mt4123_pciconf0 –port_state DN
Clear the loopback configuration using the "NO loopback" option.
mstlink -d /dev/mst/mt4123_pciconf0 –loopback NO
Enable the port.
mstlink -d /dev/mst/mt4123_pciconf0 –port_state UP
Tool Usage with NIC vs. Switch (-p Flag)
When using mstlink on NVIDIA Quantum HDR switch split ports, make sure you use the split formula
below to calculate the port number:
