Frr Node Protection (Facility Backup) - Nokia 7705 SAR-W Series Manual

MPLS Guide
If the manual bypass tunnel goes into the down state on Node B and dynamic bypass
tunnels have not been disabled, Node B will automatically signal a dynamic bypass
tunnel to protect the LSPs if a suitable one does not exist. Similarly, if an LSP is
signaled while the manual bypass tunnel is in the down state, the node will only
signal a dynamic bypass tunnel if the user has not disabled dynamic tunnels. When
the manual bypass tunnel is back up, the node will not switch the protected LSPs
from the dynamic bypass tunnel to the manual bypass tunnel.
3.7.4.2
The MPLS Fast Reroute (FRR) functionality enables PLRs to be aware of the lack of
node protection and lets them regularly probe for a node bypass via the node-
protect command.
When enabled, the node-protect command provides node protection for the
specified LSP. If node protection cannot be provided, link protection is attempted. If
link protection cannot be provided, no protection is provided. When disabled via the
no form of the command, link protection is attempted, and if link protection cannot be
provided, no protection is provided.
For example, assume the following for the LSP scenario in
3HE 18686 AAAB TQZZA

FRR Node Protection (Facility Backup)

1. LSP_1 is between PE_1 and PE_2 (via P1 and P2), and has CSPF, FRR facility
backup, and FRR node protection enabled.
2. P1 protects P2 with bypass nodes P1 - P3 - P4 - PE_4 - PE_3.
3. If P4 fails, P1 tries to establish the bypass node three times.
4. When the bypass node creation fails (there is no bypass route), P1 will protect
link P1-P2.
5. P1 protects the link to P2 through P1 - P5 - P2.
6. P4 returns online.
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Figure 9.
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