Redundant Switch Issue

I’m running into an issue with a new lab build that is probably more complex than it needs to be but it is what it is.

Here is what I have:

  • 2x Netgate 2100
  • 2x USW-48-POE

Right now I have copper SFP’s in ports 49-50 on the two switches. Switch1 Ports 49 and 50 go to Port 1 on both 2100s. Switch2 Ports 49 and 50 go to Port 2 on the 2100s. I’m going for redundant uplinks so that if for any reason SW01 goes down, SW02 can carry the load.

This setup works great as long as I only have one switch in the picture. As soon as I add SW02 both switches go offline in the Unifi application. Traffic is still being passed by SW01 but anything connected to SW02 will not.

I assume I created a loop but no idea. The Unifi app is less than helpful with troubleshooting. Anyone have any ideas?

Here is a horrible drawing of what I am trying to accomplish.

There is a write up in pfsense covering that here:
https://docs.netgate.com/pfsense/en/latest/highavailability/layer-2-redundancy.html

Thank you for the link Tom, very much appreciated. However, I was hoping more for a sample config rather than discussing how to plan for a redundant network.

I may have figured it out. I ran a CAT6 cable between the two USWs on Port 52. I’ll know more here in a bit when I reapply the VLAN configs to the switch and start powering things on but for now, it looks like I am in a good spot.

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Do you have Spanning Tree running on the switches? Absolutely required to be running or you will make a loop. If it has Rapid Spanning Tree, then that is a better option (STP or RSTP). That’s just for the switches, not sure what to do with the routers but the link Tom gave probably has the solution.