Physical port loopback
On the 7250 IXR-6/6e, IXR-10/10e, and 7250 IXR-X1b/X3b platforms, SR Linux allows you to put a physical port into loopback mode to perform diagnostic testing or troubleshooting. When a port is in loopback mode, the datapath is changed to internally loop received traffic to the transmitting side of the port or to loop transmitted traffic to the receiving side of the port. Physical port loopback can operate in two modes:
- Facility (also called local loopback): In facility mode, traffic that is normally transmitted from the port is instead redirected as if received from an external source on the same port. If the port receives traffic while in facility loopback mode, the traffic is dropped.
- Terminal (also called line loopback, or remote loopback): In terminal mode, traffic
received from an external source on the port is redirected back to the transmitting
side of the same port.
SR Linux does not support terminal mode.
Configuring loopback mode on a physical port
When an administratively enabled port (non-breakout or breakout) is put in facility (local) loopback mode, the port status immediately transitions to operationally up, even if no transceiver is installed. Similarly, if the port is a member of a static LAG (LACP mode static) and the min-link threshold is met, the LAG immediately becomes fully functional.
If a port fails to enter a configured loopback mode for any reason, the state value for the port shown in the info interface loopback-mode command remains at none.
To configure the loopback mode on a physical port, use the loopback-mode command for the interface. Supported values are: facility and none. SR Linux does not support terminal mode.
Setting the physical port loopback mode to facility
--{ + candidate shared default }--[ ]--
# info interface ethernet-1/2 loopback-mode
interface ethernet-1/2 {
loopback-mode facility
}