Peer-Peer transitive routing

 In Azure, peer-to-peer transitive routing describes network traffic between two virtual networks that is routed through an intermediate virtual network. 

For example, assume there are three virtual networks - A, B, and C. A is peered to B, B is peered to C, but A and C are not connected. For network traffic to get from A to C, it would have to travel through network B. This action is transitive routing.

A common topology in Azure is the "hub and spoke" networking architecture. This topology contains a central "hub" virtual network connected to an on-premises network, via either a VPN gateway or an ExpressRoute circuit. Additional "spoke" virtual networks that support distinct workloads, are connected to the "hub" virtual network via peering connections. This topology supports hybrid networking while providing network segmentation and delegated administration.