A method comprising: storing a content distribution map by a router, wherein the router is an access network router, is configured to receive multicast data packets over a first network interface, and is configured to communicate with one or more user devices (12-1-12-n) in the access network over a second network interface, and wherein the content distribution map indicates a plurality of permitted multicast groups that the one or more user devices in the access network are permitted to join and indicates a required bandwidth for transmitting each of the plurality of permitted multicast groups; receiving one or more user device communications, at the router across the second network interface, seeking access to one or more multicast groups; ascertaining at the router, using the content distribution map and for a multicast group indicated by a received user device communication, whether the multicast group is one of the plurality of permitted multicast groups that the one or more user devices are permitted to join; conditioned upon ascertaining that the multicast group is one of the plurality of permitted multicast groups, determining (308, 400-1), based on the required bandwidth for transmitting the multicast group indicated by the content distribution map and information describing current data traffic levels for the access network, whether there is sufficient bandwidth on the access network to begin transmitting data of the multicast group to the one or more user devices; conditioned upon determining that there is sufficient bandwidth on the access network to begin transmitting the data of the multicast group to the one or more user devices, transmitting one or more router communications from the router, across the first network interface, requesting membership in the multicast group; receiving multicast data packets at the router, over the first network interface and in response to the one or more router communications, the multicast data packets comprising content data associated with the multicast group; and forwarding data from the multicast data packets over the second network interface. storing a content distribution map by a router, wherein the router is an access network router, is configured to receive multicast data packets over a first network interface, and is configured to communicate with one or more user devices (12-1-12-n) in the access network over a second network interface, and wherein the content distribution map indicates a plurality of permitted multicast groups that the one or more user devices in the access network are permitted to join and indicates a required bandwidth for transmitting each of the plurality of permitted multicast groups; receiving one or more user device communications, at the router across the second network interface, seeking access to one or more multicast groups; ascertaining at the router, using the content distribution map and for a multicast group indicated by a received user device communication, whether the multicast group is one of the plurality of permitted multicast groups that the one or more user devices are permitted to join; conditioned upon ascertaining that the multicast group is one of the plurality of permitted multicast groups, determining (308, 400-1), based on the required bandwidth for transmitting the multicast group indicated by the content distribution map and information describing current data traffic levels for the access network, whether there is sufficient bandwidth on the access network to begin transmitting data of the multicast group to the one or more user devices; conditioned upon determining that there is sufficient bandwidth on the access network to begin transmitting the data of the multicast group to the one or more user devices, transmitting one or more router communications from the router, across the first network interface, requesting membership in the multicast group; receiving multicast data packets at the router, over the first network interface and in response to the one or more router communications, the multicast data packets comprising content data associated with the multicast group; and forwarding data from the multicast data packets over the second network interface.