Today, many years after IP multicast was first proposed, is not widely used in the Internet. One of the reasons is the potentially large multicast forwarding state that needs to be maintained in the routers. In this work we investigate this state scalability problem in the context of an IP VPN service built using MPLS. We focus on point-to-multipoint applications such as distribution of TV programs to multiple clients of a VPN provider. Using recent work on multicast MPLS, we show that with some very simple modifications to the signaling protocols used to establish the point-to-multipoint MPLS distribution trees it is possible to achieve significant reduction in the forwarding state required for setting up a large number of distribution trees. These savings in forwarding state can be achieved without having to send multicast traffic to receivers that do not want to receive it, also known as traffic leakage.
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