The P2MP TE feature does not support penultimate-hop popping. Therefore, the egress router must allocate
an explicit null or non-null label.
Note
Figure 4: How Packets Traverse the P2MP Tree
When sub-LSPs share a common router (branch point) and use the same ingress interface of the router, the
same MPLS label is used for forwarding. The multicast state is built by reusing the MPLS labels at the branch
points, as shown in the figure below, where MPLS label 17 is shared by two sub-LSPs that both use router
C.
Figure 5: Reusing MPLS Labels in Branch Points
MPLS Traffic Engineering Path Calculation and Setup Configuration Guide, Cisco IOS XE Release 3S (Cisco ASR
920 Series)
15
MPLS Point-to-Multipoint Traffic Engineering
How P2MP TE Traffic Is Forwarded