4. Application to IP multicast transport

As discussed in , an MPLS tree can be used to transport :

• native IP multicast traffic. For example, an MPLS tree can be used to transport an IP multicast group or a set of IP multicast groups;

• multicast traffic from an IP VPN or a Layer 2 VPN (Ethernet, ATM, TDM...). In this case, there will be a separate tree for each VPN;

• MPLS traffic (label stacking), in the case of hierarchical trees.

This last section deals with native IP multicast transport in MPLS trees.

Here, we'll look at a scenario where IP multicast clouds are connected by an MPLS multicast cloud; we'll only be interested in the P2MP MPLS-TE mode, which is the only one implemented at the time of writing.

Figure...