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350-501 · Question #337
350-501 Question #337: Real Exam Question with Answer & Explanation
The correct answer is A: TI-LFA uses PQ or P and Q nodes on the post-convergence path to compute the backup path.. TI-LFA computes a backup path for Segment Routing by leveraging the post-convergence path and identifying specific P and Q nodes to ensure loop-free forwarding after a failure.
MPLS and Segment Routing
Question
Which two features describe TI-LFA? (Choose two.)
Options
- ATI-LFA uses PQ or P and Q nodes on the post-convergence path to compute the backup path.
- BPost-convergence, TI-LFA considers the next-hop neighbor to calculate the backup repair path.
- CTI-LFA works with point of local repair when the PQ node supports only LDP capability.
- DUnlike RLFA, TI-LFA works without the PQ node and provides double segment failure protection.
- ETI-LFA leverages the post-convergence path that carries data traffic after a failure.
Explanation
TI-LFA computes a backup path for Segment Routing by leveraging the post-convergence path and identifying specific P and Q nodes to ensure loop-free forwarding after a failure.
Common mistakes.
- B. TI-LFA considers the entire post-convergence path and its properties, not just the isolated next-hop neighbor, to ensure loop-freedom for the repair path.
- C. TI-LFA is a Segment Routing FRR mechanism and does not depend on LDP capability for PQ nodes; it uses SR identifiers (SIDs) for its operations.
- D. TI-LFA explicitly relies on the concept of P and Q nodes to compute its backup path, and its primary focus is 100% coverage for single link/node failures, not 'double segment failure protection'.
Concept tested. Segment Routing TI-LFA characteristics
Topics
#TI-LFA#Fast Reroute#Segment Routing#MPLS Protection
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