Cisco ACI L2 Out

Hi Guys,

Im planning to setup a ACI Fabric with 4 spines and a bunch of leafs and want to stretch a L2 domain to some legacy cisco 3850 switches out of the aci.

as ACI is acting in that case like a Ethernet Hub it will forward BPDU Packets over the Fabric, but will, as it doesnt support it, not be part of the spanning tree.

has anybody already expierience with such a architecture or similar? How do you rate the chance of a loop if STP fails?

cheers