350-501 Question #384: Real Exam Question with Answer & Explanation

Question

How does Cisco MPLS TE use OSPF extensions to allow for optimized transit between a headend router and a destination router?

Options

• ARouter LSAs share router link advertisements to each router within the MPLS environment so that
• BASBR Summary LSAs share OSPF domain information so that the two routers know how to
• CNetwork LSAs share RSVP information to build the tunnel between the two routers.
• DOpaque LSAs calculate and establish unidirectional tunnels that are set according to the network

Explanation

Cisco MPLS Traffic Engineering leverages OSPF Opaque LSAs to distribute critical traffic engineering attributes, enabling headend routers to calculate and establish explicit, unidirectional tunnels based on network constraints.

Common mistakes.

• A. Router LSAs (Type 1) advertise directly connected links and their metrics but do not carry the extended attributes required for MPLS Traffic Engineering.
• B. ASBR Summary LSAs (Type 4) are used to advertise the location of an Autonomous System Boundary Router to other areas, not for MPLS TE path computation.
• C. Network LSAs (Type 2) are generated by the Designated Router to describe the multiaccess segment and the routers connected to it, not to share RSVP information for tunnel building.

Concept tested. MPLS TE OSPF extensions

Reference. https://www.cisco.com/c/en/us/td/docs/ios_xr_sw/iosxr_r4-0/mpls/command/reference/cr-mpls/mplste.html

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