A method, in an intermediate node in a control plane network, includes receiving a setup message from an originating node, wherein the setup message is sent towards a terminating node on a computed path in the control plane network, and the setup message indicates associated Layer 0 attributes; validating the associated attributes/constraints based on locally available resources; and performing one of: forwarding the setup message on the path towards the terminating node when validation is successful; forwarding the setup message on the path towards the terminating node with updated information indicating a rejection cause and additional information when the validation is unsuccessful, but a modification of the Layer 0 attributes/constraints is possible; and forwarding a release message on the path back to the originating node with updated information indicating a rejection cause and additional information when the validation is unsuccessful and no modifications of the Layer 0 attributes/constraints are possible.