Exam 350-501 topic 1 question 381 discussion

Answer is "C". Directly from the Cisco Press Wedbsite: Facility backup uses label stacking to reroute multiple protected TE LSPs using a single backup TE LSP. https://www.ciscopress.com/articles/article.asp?p=520184&seqNum=4

I think it comes down to the interpretation of the word "provide" at the end of the question. Both A and C seem correct to me, but C is more like how RSVP-TE FRR Facility Backup works, not what it actually does or "provides". I also really like the phrasing of A. It specifically says 'a' bypass, which is exacly what facility backup is. One pipe for all the tunnels that pass through the router, packed into one single bypass LSP.

I go with C. https://www.ciscopress.com/articles/article.asp?p=520184&seqNum=4

Answer: C is correct https://www.ciscopress.com/articles/article.asp?p=520184&seqNum=4 Note MPLS TE FRR specifications offer two protection techniques: facility backup and one-to-one backup. Facility backup uses label stacking to reroute multiple protected TE LSPs using a single backup TE LSP. One-to-one backup does not use label stacking, and every protected TE LSP requires a dedicated backup TE LSP. The remainder of this section focuses on the facility backup approach because of its greater scalability and wider use.

From MPS TE of Cisco Press: MPLS TE FRR specifications offer two protection techniques: facility backup and one-to-one backup. Facility backup uses label stacking to reroute multiple protected TE LSPs using a single backup TE LSP. One-to-one backup does not use label stacking, and every protected TE LSP requires a dedicated backup TE LSP. The remainder of this section focuses on the facility backup approach because of its greater scalability and wider use. So option C is correct

How FRR works FRR works by creating a backup tunnel for each MPLS TE LSP. The backup tunnel is pre-provisioned and is configured to bypass the failed link or node. When a link or node failure is detected, the router at the point of failure (PLR) will quickly reroute traffic over the backup tunnel. This rerouting process is called local repair.