Skip to main content
Version: current

Bridging and Switching Case Studies

These case studies show common RouterOS bridging and switching designs, including VLAN switching, IGMP and MLD snooping, spanning tree, loop protection, and switch-chip behavior. Use them as practical examples for Layer 2 deployments and troubleshooting.

📄️Loop Protect

The loop protect feature can prevent Layer2 loops by sending loop protect protocol packets and shutting down interfaces in case they receive loop protect packets originating from themselves. The feature works by checking the source MAC address of the received loop-protect packet against the MAC addresses of loop-protect enabled interfaces. If the match is found, loop protect disables the interface that received the loop protect packet. A log message warns about this event and the interface is marked with a loop protect comment by the system. The RouterOS loop protect feature can be used on bridged interfaces as well as on Ethernet interfaces which are set for switching in RouterBoard switch chips.

📄️Wireless VLAN Trunk

A very common task is to forward only a certain set of VLANs over a Wireless Point-to-Point (PtP) link. This can be done using bridge VLAN filtering and should be used instead of any other methods (including bridging VLAN interfaces). Let's say we need to forward 2 different VLANs over a Wireless link and all other VLAN IDs should be dropped. VLAN 10 is going to be our Internet traffic while VLAN 99 is going to be for our management traffic. Below you can find the network topology: