A service provider is designing a new backbone based on an IGP and MPLS what are two valid reasons for implementing MPLS-TE as well? (Choose two)

Question

Options

• AMPLS-TE is required to reroute traffic within less than 1 second in case of a link failure inside the
• BMPLS-TE can detect and react to neighbor failures faster than IGPs can
• CMPLS-TE is required to route different MPLS QoS Service classes through different paths
• DMPLS-TE is required to create backup paths independently from the IGP
• EMPLS-TE is a prerequisite for implementing RSVP in the backbone

Explanation

MPLS-TE: Valid Reasons for Implementation

C and D are the correct answers.

C is correct because standard MPLS with an IGP routes all traffic along the same shortest path - it has no concept of routing different QoS service classes (e.g., voice vs. best-effort) through separate physical paths. MPLS-TE with DS-TE (Differentiated Services Traffic Engineering) enables this by establishing class-specific Label Switched Paths (LSPs).

D is correct because MPLS-TE explicitly computes and signals backup tunnel paths using CSPF (Constrained Shortest Path First) and RSVP-TE, independently of IGP shortest-path decisions. This allows pre-provisioned failover paths that the IGP would never naturally select.

Why the distractors are wrong:

• A is misleading - sub-second rerouting is achievable with MPLS-TE FRR, but IGPs combined with BFD can also achieve fast convergence without MPLS-TE, so MPLS-TE is not strictly required for this.
• B is false - MPLS-TE has no native failure detection mechanism; BFD handles fast detection and works with IGPs directly.
• E reverses the dependency - RSVP (as RSVP-TE) is a prerequisite for MPLS-TE signaling, not the other way around.

Memory tip: Think of MPLS-TE as solving two problems IGPs can't: Quality separation (C - different paths per class) and Diverging from the IGP's shortest path for backup (D - independent backup paths). "TE = Traffic Engineering = Tailor Every path."

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