The invention relates to a method, network node, router, serving node and system for performing multicast in a point-to-point packet-switched oriented telecommunication network. The basic idea is to introduce pre-configured multicast transmission for parts of a network. This is done by creating pre-configured transport multicast group tunnels between a router and a serving node in order to transport the multicast data. Further the present invention describes the possibility of multiplexing of the multicast data streams on a pre-configured transport multicast group tunnel. In particular the invention is applicable for multicasting in networks, like UMTS with a scarce number of resources, in the IP network between the SGSN and GGSN for example on the Gn interface.