In one to one backup each LSP has its own detour LSP in one to one backup policy although it requires more granularity but it consumes more resources.
The HE router sends a path message with the one to one desired flag set.
If the node protection is desired the session attribute flag also has the node protection desired flag set.
After the FRR is established all the routers except the tail router assumes the role of PLR and creates a detour path.
The detour LSP has the same tunnel-id and LSP-id as the primary LSP
They all have a Detour object containing the PLR router ip address and the ip address that the detour LSP is trying to avoid.
All the detour LSP have the following naming conventions Protected LSP name::Protected LSP path name_detour.
lsp-to-163::163_detour means that this detourlsp-to-163 and path name 163.
If a primary LSP traverses n hops in the network then there will be n-1 LSP's in there network, although no detour configuration is necessary however in a highly scalable network this increases the number of LSP to a huge number.
The PLR notifies the HE router of the failure by setting the local-repair-in-use flag set in the path error message.
When there is a failure the PLR tries to establish node protection with 3 attempts if node protection is not possible then the router resorts to link protection.
First the primary LSP is set up by exchanging the labels
When the PLR signals the detour LSP to the merge point, the merge point distributes labels for the detour LSP and also It programs to swap the label 200 with label 100 if the detour LSP is used.
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