352-001 Question #459: Real Exam Question with Answer & Explanation

The correct answer is C: 1:N protection. 1:N protection uses a single shared backup LSP to protect multiple primary LSPs that all converge at the same merge point, making it the most scalable RSVP-TE protection model.

Question

You are asked to design an RSVP-TE LSP protection solution for a large service provider network. Which traffic protection mechanism is highly scalable and ensures that multiple LSPs always terminate at the same merge point?

Options

Adetour LSPs
B1:1 protection
C1:N protection
Dshared-explicit reservation style

Explanation

1:N protection uses a single shared backup LSP to protect multiple primary LSPs that all converge at the same merge point, making it the most scalable RSVP-TE protection model.

Common mistakes.

A. Detour LSPs provide per-LSP local repair by creating individual bypass tunnels around a failed node or link, which does not scale well in large networks because every protected LSP requires its own dedicated detour path.
B. 1:1 protection dedicates one unique backup LSP for every single primary LSP, consuming significantly more bandwidth and signaling resources, making it poorly suited for large-scale deployments.
D. Shared-explicit reservation style is an RSVP session attribute that allows multiple senders to share a single reservation object, but it is not a defined LSP protection model and does not prescribe a common merge point architecture.

Concept tested. RSVP-TE 1:N LSP protection scalability and merge point

Reference. https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/mp_te_path_protect/configuration/xe-16/mp-te-path-protect-xe-16-book/mp-te-1-to-1-path-protection.html

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