Huawei Nokia Telefonica Telefonica Infinera China Unicom CTTC NEC Nokia Ericsson There are scenarios, typically in a hierarchical SDN context, in which an orchestrator may not have detailed information to be able to perform an end-to-end path computation and would need to request lower layer/domain controllers to calculate some (partial) feasible paths. Multiple protocol solutions can be used for communication between different controller hierarchical levels. This document assumes that the controllers are communicating using YANG-based protocols (e.g., NETCONF or RESTCONF). This document describes some use cases where a path computation request, via YANG-based protocols (e.g., NETCONF or RESTCONF), can be needed. This document also proposes a yang model for a stateless RPC which complements the stateful solution defined in [TE-TUNNEL].