Setup redundant/diverse fiber circuits to the same network at two different sites

Hey all,

There is a network (GoldNet) that exists in two different sites, let’s call them Site A and Site B. These two sites contain switches that allow access to this network as well as routers, etc.

I’m at Site C and setting up diverse fiber paths (two separate 1G wave circuits) to Site A and B. These are diverse paths.

I realize there are probably many different ways to setup connectivity to the GoldNet but I’m looking to hear some ways that you all have set this up in the past to take advantage of automatic failover if one of the fiber circuits gets cut or goes down.

Is there a layer1 or layer2 way to do this? Probably? But is this the best way to do this?

Should the redundancy/failover happen at Layer3?

Thanks in advance!