H3C Technologies H3C S3100 Series Switches - Manual (Page 146)

1-5
z If you have additionally enabled the loopback port auto-shutdown function on the port, the system
will shut down the port, and send log and trap messages to the terminal. After the loop is removed,
you need to use the undo shutdown command to bring up the port.
z If you have not enabled the loopback port auto-shutdown function on the port, the port will
automatically resume the normal forwarding state after the loop is removed.
2) If a loop is found on a trunk or hybrid port, the system sends log and trap messages to the terminal.
If you have additionally enabled the loopback port control function or the loopback port
auto-shutdown function, the system will deal with the port accordingly:
z If the loopback port control function is enabled on the port, the system will set the port to the block
state (ports in this state cannot forward data packets), send log and trap messages to the terminal,
and remove the corresponding MAC forwarding entry. After the loop is removed, the port will
automatically resume the normal forwarding state.
z If the loopback port auto-shutdown function is enabled on the port, the system will shut down the
port and send log and trap messages to the terminal. After the loop is removed, you need to use the
undo shutdown command to bring up the port.
You cannot enable both the loopback port control function and the loopback port auto-shutdown
function on a port. If you do so, the function configured later will take effect.
Table 1-5 Configure loopback detection for Ethernet port(s)
Operation Command Remarks
Enter system view system-view —
Enable loopback detection
globally
loopback-detection enable
Optional
By default, the global loopback detection
function is enabled if the device boots with
the default configuration file (config.def); if
the device boots with null configuration, this
function is disabled.
Enable loopback detection
on the specified ports in
bulk
loopback-detection
interface-list enable
Optional
By default, the loopback detection function
is enabled on ports if the device boots with
the default configuration file (config.def); if
the device boots with null configuration, this
function is disabled.
Set the interval for
performing port loopback
detection
loopback-detection
interval-time time Optional
The default is 30 seconds.
Enter Ethernet port view
interface interface-type
interface-number
—