Label Switching Routers
Page 32 7450 ESS MPLS Guide
When the manual bypass tunnel is back into the UP state, the node will not switch the protected
LSPs from the dynamic bypass tunnel into the manual bypass tunnel.
FRR Node-Protection (Facility)
The MPLS Fast Re-Route (FRR) functionality enables PLRs to be aware of the missing node
protection and lets them regularly probe for a node-bypass. The following describes an LSP
scenario:
Figure 4: FRR Node-Protection Example
Where:
• LSP 1: between PE_1 to PE_2, with CSPF, FRR facility node-protect enabled.
• P_1 protects P_2 with bypass-nodes P_1 -P_3 - P_4 - PE_4 -PE_3.
• If P_4 fails, P_1 tries to establish the bypass-node three times.
• When the bypass-node creation fails, P_1 will protect link P_1-P_2.
• P_1 protects the link to P_2 through P_1 - P_5 - P_2.
• P_4 returns online.
Since LSP 1 had requested node protection, but due to lack of any available path, it could only
obtain link protection. Therefore, every 60 seconds the PLR for LSP 1 will search for a new path
that might be able to provide node protection. Once P_4 is back online and such a path is available,
A new bypass tunnel will be signalled and LSP 1 will get associated with this new bypass tunnel.
al_0205
P_5
PE_4
PE_3
PE_1
P_1
P_2
PE_2
P_3
P_4
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