1. A method comprising: receiving a request for content, at a requestor having one or more processors, from a first receiver; initiating a quality of service aware hybrid tree construction by sending a multicast service level specification message to a first overlay tree manager; dividing the tree at the overlay tree manager and communicating with other overlay tree managers in the network; computing, at each overlay tree manager, a shortest path tree using a constrained algorithm; sending, from each overlay tree manager, a multicast service level specification message to each IP manager in the network requesting that the IP managers construct an IP multicast tree and install the tree on one or more corresponding routers; and enforcing multicast routes and quality of service on the one or more routers.