Leveraging Software-Defined Networking (SDN) and middleboxes, application-level policies can be propagated to the network. SMART is an SDN middlebox architecture that differentiates network flows based on tenant inputs. By leveraging FlowTags software middlebox in addition to the OpenFlow rules, it supports a larger scope of tenant preferences and rules from the application layer to alter the network flow behaviour. It thus ensures timely delivery of priority flows by dynamically diverting them to a less congested path or even cloning the packets of higher priority flows along with the original flow.