Label stack reduction is only attempted when the path protection local-sr-protection command is disabled or is configured to the value of preferred.
If local-sr-protection is configured to a value of none or mandatory, the command is ignored, and the fully explicit path computed out of Phase 1 is returned by the TE-DB CSPF routine to MPLS. This is because a node SID used to replace an adjacency SID or an adjacency set SID can be unprotected or protected by LFA and this is based on local configuration on each router which resolves this node SID but is not directly known in the information advertised into the TE-DB. Therefore, CSPF cannot enforce the protection constraint requested along the path to that node SID.