The 5G-TRANSFORMER project aims at transforming today's mobile transport networks into an SDN/NFV-based platform, which offers slices tailored to the needs of vertical industries. The paper describes the 5G-TRANSFORMER resource management layer, namely MTP, and its main functionalities such as resource abstraction, resource information modeling and orchestration, and service instantiation. Then, it focuses on the ETSI-based interfaces exploited for the interaction between the control and management plane elements. Finally, the paper reports an MTP implementation including messages reporting resource abstraction.