A system comprising: a plurality of non-last-hop routers 'non-LHRs' of a network , the non-LHRs configured with a multicast distribution tree for a multicast group to transport first multicast packets of a multicast flow toward one or more last-hop routers 'LHRs' , wherein a router of the non-LHRs is configured to send, to each of the one or more LHRs, a multicast group notification message including an association of the multicast group and a session identifier for an application session, wherein each of the one or more LHRs is configured to store the association of the multicast group and the session identifier for the application session, wherein the router of the non-LHRs is configured to receive unicast packets for the application session associated with the multicast group, encapsulate the unicast packets in a multicast header to generate the first multicast packets for distribution using the multicast distribution tree, and output the first multicast packets; the one or more LHRs, wherein the one or more LHRs are interested receivers of the multicast group, wherein an LHR of the one or more LHRs is configured to receive a content request from a client of one of the clients of the application session, wherein the LHR is configured to, in response to determining a session identifier for the content request matches the session identifier for the application session, based on the association of the multicast group and the session identifier for the application session, request to join the multicast group, and wherein the one or more LHRs are configured to receive the first multicast packets of the multicast flow, extract the unicast packets for the application session, and send the unicast packets to one or more clients of the application session. a plurality of non-last-hop routers 'non-LHRs' of a network , the non-LHRs configured with a multicast distribution tree for a multicast group to transport first multicast packets of a multicast flow toward one or more last-hop routers 'LHRs' , wherein a router of the non-LHRs is configured to send, to each of the one or more LHRs, a multicast group notification message including an association of the multicast group and a session identifier for an application session, wherein each of the one or more LHRs is configured to store the association of the multicast group and the session identifier for the application session, wherein the router of the non-LHRs is configured to receive unicast packets for the application session associated with the multicast group, encapsulate the unicast packets in a multicast header to generate the first multicast packets for distribution using the multicast distribution tree, and output the first multicast packets; the one or more LHRs, wherein the one or more LHRs are interested receivers of the multicast group, wherein an LHR of the one or more LHRs is configured to receive a content request from a client of one of the clients of the application session, wherein the LHR is configured to, in response to determining a session identifier for the content request matches the session identifier for the application session, based on the association of the multicast group and the session identifier for the application session, request to join the multicast group, and wherein the one or more LHRs are configured to receive the first multicast packets of the multicast flow, extract the unicast packets for the application session, and send the unicast packets to one or more clients of the application session. <EOS>