Contoso has two ExpressRoute circuits, each terminating in a different region: one connects a data center in London (peered at a London provider location) and another connects a data center in Chicago (peered at a Chicago provider location). Both circuits use private peering and connect to Azure VNets successfully. The network team now needs the London and Chicago on-premises data centers to communicate directly with each other over the Microsoft backbone, without routing traffic through an Azure VNet or the public internet. Which solution meets this requirement?