You are asked to design an RSVP-TEL LSP protection solution for a large service provider network .Which traffic protection mechanism is highly scalable and ensure that multiple LPS always terminate…

Question

Options

• AShared explicit protection.
• BDetour LSPs.
• C1:N protection.
• D1:1 protection.

• A
  13% (5)
• B
  5% (2)
• C
  80% (32)
• D
  3% (1)

Explanation

1:N protection is correct because it uses a single backup LSP to protect N working LSPs simultaneously. The architectural requirement for 1:N to function is that all N protected LSPs must share the same merge point (egress node) - this is not a coincidence but a hard design constraint. This makes it extremely scalable: one pre-signaled backup handles failures across many working paths without multiplying state or resource consumption.

Why the distractors are wrong:

• A (Shared explicit protection): Shares backup bandwidth among LSPs but does not enforce a common merge point - LSPs can terminate at different egress nodes, making it a different (more flexible but less constrained) model.
• B (Detour LSPs): A Fast Reroute local repair technique that creates per-LSP bypass tunnels around a single failure point. It is per-LSP state-heavy and does not require or guarantee a shared merge point.
• D (1:1 protection): Dedicates one backup LSP per working LSP, which is the least scalable option - resource usage scales linearly with the number of protected paths.

Memory tip: Think of the ratio literally - 1:N means one backup, many workers, one destination. The "one destination" is the shared merge point that makes the math work. If LSPs went to different places, the single backup couldn't serve them all.

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