RouterOS L2 Loop Protect




It prevent Layer2 loops by sending loop protect protocol packets and

shutting down interfaces in case they receive loop protect packets originated from themselves.

Works by

checking the source MAC address of the received loop protect packet against MAC addresses of loop protect enabled interfaces.

Loop Protect works on Ethernet, VLAN, EoIP, VxLAN interfaces and its packets are encapsulated with EtherType 0x9003.


  • loop-protect: default works as turned off.
  • Send Interval: 5s   # Default
  • Disable Time: 5m   # Default

Even though loop-protect can work on interfaces that are added to a bridge,

it is still recommended to use (R/M)STP rather than loop-protect

since (R/M)STP is compatible with most switches STP variants provide much more configuration options to fine-tune your network.



Time        Feb/08/2022 15:52:10
Buffer      memory
Topics      interface warning
Message     ether2-master received loop protect packet originated from 6C:3B:6B:xx:xx:xx (ether2-master)

loop-protect-status (on | off | disable)    

    on - the interface is sending and listening for loop protect packets
    disable - the interface has received loop protect packet and disabled itself to prevent loop.

 * Master Port: "ether2-master" 開了其他port就用到.