[kazen44]

avoid spanning tree like the plague in large datacenter networks as well. because of the scale and it becomes an impossible black box.

there is a reason evpn exists, and is it to solve this exact issue by making gateways handle all logic normally stretched across to the other side of a l2vpn.

[ArchOversight]

I am a firm believer in layer 3 everywhere. No more layer 2 connectivity as much as possible.

It's how I deployed VM's at scale using BGP from the VM host to the top of rack switch. VM's could route to each other, but no layer 2 connectivity.

It allowed for easy migration of systems between VM hosts too, as the ToR would learn the /128 or /32 and traffic would route to the new VM host.

[p_l]

Exactly - your L2 Ethernet shouldn't go beyond immediate connection between end system and first L3 router, in DC conditions it should be to Tor... Or on-Hypervisor router.

Larger L2 spans should be done only when required, and preferably with things like TRILL/SPB.