350-501 Question #412: Real Exam Question with Answer & Explanation

Question

Refer to the exhibit. An engineer must implement a traceroute operation to verify the R1 point-to- multipoint LSP connections. The traceroute operation must return all labels and hop-by-hop IP addresses for destinations 10.20.0.1, 10.30.0.1, and 10 40.0.1, and the maximum number of hops is 4. Which command must be executed to meet the requirements?

Options

• Atraceroute mpls ipv4 10.30.0.1/32 fec-type generic
• Btraceroute mpls ipv4 10.20.0.1/32 ttl 4
• Ctraceroute mpls traffic-eng tunnel-mte 10 ttl 4
• Dtraceroute mpls traffic-eng tunnel-mte 10 responder-id 10.40.0.1

Explanation

To verify point-to-multipoint MPLS Traffic Engineering LSP connections and gather hop-by-hop label and IP information for all branches, the traceroute mpls traffic-eng tunnel-mte command is used with the specified maximum hop count.

Common mistakes.

• A. traceroute mpls ipv4 is used for tracing LDP or IP-routed MPLS paths to a single IPv4 destination, not specifically for P2MP Traffic Engineering LSPs.
• B. Similar to A, traceroute mpls ipv4 targets a single destination and does not provide comprehensive tracing for a P2MP TE tunnel's multiple branches.
• D. The responder-id option in traceroute mpls traffic-eng tunnel-mte is used to trace a specific branch to a single leaf of a P2MP tunnel, not all destinations or branches as required by the question.

Concept tested. MPLS TE P2MP traceroute

Reference. https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/mpls/command/mpls-cr-a-d/mpls-cr-a-d-chapter_010.html#wp4029141065

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