•
From PE1 to PE3, the sub-LSP travels the following path: PE1 -> P01 -> P03 -> PE3
•
From PE1 to PE4, the sub-LSP travels the following path: PE1 -> P01 -> P04 -> PE4
Node P01 is a branch node that does packet replication in the MPLS forwarding plane; ingress traffic originating
from PE1 will be replicated towards routers P02, P03, and P04.
Figure 6: P2MP TE Link Protection Example
To protect the three sub-LSPs, separate point-to-point backup tunnels are signaled. . In this example, router
P01 is the Point of Local Repair (PLR) and routers P02, P03, and P04 are Merge Points (MPs).
If a link failure occurs between routers P01 and P04, the following events are triggered:
1
Router P01 switches traffic destined to PE4 to the backup tunnel associated with P04.
2
Router P01 sends RSVP path error messages upstream to the P2MP TE headend router PE1. At the same
time, P01 and P04 send IGP updates (link state advertisements (LSAs)) to all adjacent IGP neighbors,
indicating that the interfaces associated with links P01 through P04 are down.
3
Upon receiving RSVP path error messages and IGP LSA updates, the headend router triggers a P2MP TE
tunnel reoptimization and signals a new sub-LSP. (This occurs if you have specified dynamic path creation.)
MPLS Traffic Engineering Path Calculation and Setup Configuration Guide, Cisco IOS XE Release 3S (Cisco ASR
920 Series)
19
MPLS Point-to-Multipoint Traffic Engineering
Using FRR to Protect P2MP TE Links
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