Helo all. I have a CRS317-1g-16s+ running in Switch Mode. I'm sure i'm being plagued by terminology, but I'm hoping someone else on the forum has done what I'm trying to do.
So we have an existing network of FortiSwitch. Those use FortiLink to communicate with each other (I think it's just a LAG setup with an unknown vlan) but i'm not sure.
What I am trying to accomplish is utilize the CRS317-1g-16s+ as an aggregation switch so that the remote switches and core switch can live on the Mikrotik, rather than switch to switch on the fortinet sfp ports.
So, I have tried messing with VLANs, I've tried LAG, but I can' seem to get traffic to cross the Mikrotik CRS. I dont believe Forti is doing anything proprietary with their switches on fortilink.

Has anyone else tried this? Any ideas where I might look next?

Thank you!

Out of the box, it should come configured as a "dumb switch", with all ports in a single bridge, which is then hardware-offloaded. The MTU is usually set at 1500, so you might have to go in and change the L2MTU on all the ports.

You might have to disable RSTP on the bridge, but be careful not to plug more than one cable per switch until you identify exactly what's going on.

The MTU is usually set at 1500, so you might have to go in and change the L2MTU on all the ports.

Why? MTU has nothing to do with L2MTU.

I have tried messing with VLANs, I've tried LAG, but I can' seem to get traffic to cross the Mikrotik CRS. I dont believe Forti is doing anything proprietary with their switches on fortilink.

FortiLink defines the management interface and remote management protocol, i.e. just the control plane.

You need to know how they are configured and implement the equivalent on the Mikrotik. LAG or MLAG? What type of STP? What tagged and untagged VLANs?