L2 Loop Protection feature allows loop detection in downstream switches that do not run spanning tree. It can optionally disable the associated port on loop detection.
The Loop Protection feature is not intended for ports that serve as uplinks between spanning tree aware switches. Loop Protection feature is designed for unmanaged switches which drop spanning Tree BPDUs. This feature detects physical and logical loops between Ethernet ports on a device. The feature needs to be enabled globally before enabling it at the interface level for the system policy filter to be installed.