Policy-based network transmission routing

Policy-based network transmission routing is provided by accessing routing metadata in a wrapper of the transmission packet, the routing metadata representing a feature of the source or the destination, comparing the routing metadata to routing policy data associated with each of multiple routing policies defined within a routing policy structure, identifying, based on the comparing, one or more routing policies applicable to the transmission packet, identifying, based on the routing policy data, a highest priority routing policy from the one or more routing policies, the highest priority routing policy defining a route constraint usable to limit a selection of available routes to the destination, and selecting the route from the available routes based on the route constraint.