Routers of a content network include routing entries that specify aggregation levels, enabling the routers to establish a tree-based topology within an aggregation realm for distribution of broadcast packets. Each router is configured to have a prescribed aggregation level within the aggregation realm, and identify a network-directed broadcast packet based on detecting a prescribed pluricast code at a corresponding prescribed prefix location relative to the prescribed aggregation level. Each router also is configured for storing a registration request within its routing entries, and propagating the registration request to other routers within the aggregation realm. Each registration request includes a bit mask according to one of the prescribed aggregation levels. Hence, client-based registration requests can be propagated throughout the aggregation realm for rules-based coalescence of subscriber groups throughout the aggregation realm.