Common multicast tree shared by all layers/streams belonging to one session,
is essential to provide multicast-based congestion avoidance. It enables both
synchronization of layered data (in the case of layered multicast) or streams (in
the case of multicast stream replication) and stable congestion control. 
Although many authors have been addressed the problem of multicast 
transmission, the methodology of building common delivery trees still remains
an unresolved issue. In the paper, a new solution of that problem is proposed - 
a multigroup communication based on active network technology.