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Hierarchy Level


Calculate post-convergence MPLS fast reroute (FRR) backup next hops for the IS-IS protocol using segment routing (SR). Topology-independent loop-free alternate (TI-LFA) provides protection against link failure, node failure, and fate-sharing failures. By default, Junos OS provides link protection. Junos OS allows you to control the maximum number of equal-cost multipath (ECMP) backup paths installed for a given destination. Junos OS also allows you to control the maximum number of labels in the installed backup paths. Configure the use-source-packet-routing statement at [edit protocols isis backup-spf-options] hierarchy level to allow the backup paths to be available for inet.0 routing table along with inet.3 routing table.



Set the maximum number of equal-cost post-convergence backup paths to be installed. For remote LFA, the IS-IS protocol installs only one backup path. The maximum backup path range allows you to install multiple backup paths

  • Default: 1

  • Range: 1-8


Set the maximum number of labels used to construct a post-convergence backup path. If the backup path for a particular prefix requires more number of labels than the configured maximum labels then the backup path for that particular prefix is not installed.


If the maximum-labels option is not configured, then the number of labels that gets pushed stops at 3.

  • Default: 3

  • Range: 2-5

Required Privilege Level


Release Information

Statement introduced in Junos OS Release 17.4R1 for MX Series, PTX Series, and QFX Series.