IP Multicast is an important enabling service for the current and future Internet. With the explosive, growth of the Internet, a challenging issue facing IP multicast is scalability, in particular, the problem of multicast forwarding state and control explosion. In this paper, we propose a new methodology to address the multicast scalability problem for backbone domains Multicast Tunneling with Branch Filtering (MTBF). This multicast group aggregation scheme is designed on top of the inter-domain protocol architecture such as MASC/BGMP, and is independent of any underlying intra-domain multicast protocols. It aggregates multicast groups by constructing Border Router (BR)-based multicast routing trees and forwards data by using an encapsulation technique called Multicast Tunneling (MT). To minimize excess traffic due to aggregate multicast address based data forwarding, an efficient Dynamic Filtering Point Selection (DFPS) algorithm is used. The feasibility and performance of our scheme is demonstrated through analysis and simulations.