350-501 Question #631: Real Exam Question with Answer & Explanation

Question

Refer to the exhibit. This enterprise configured MPLS within its network to connect offices that span different geographic areas, with LDP running between connected neighbors. At each office, including headquarters, the networks are running OSPF with a similar configuration. Which additional action must the engineering team take to support a more reliable connection between MPLS and OSPF?

Options

• AImplement targeted LDP sessions between the peers connected to interface g0/1 and g0/2.
• BImplement MD5 authentication between LDP and OSPF neighbors to secure the connection.
• CImplement LDP session protection to maintain uptime during outages.
• DImplement MPLS LDP sync to synchronize OSPF and LDP.

Explanation

To achieve a more reliable connection between MPLS and OSPF, the network engineering team needs to implement a mechanism that can sustain LDP sessions during link failures.

Common mistakes.

• A. Targeted LDP sessions are used for non-directly connected peers or specific VPN applications, not for improving general reliability over directly connected links during outages.
• B. MD5 authentication secures LDP sessions against unauthorized access but does not prevent session termination or improve reliability during link failures.
• D. MPLS LDP sync synchronizes LDP with IGP convergence to prevent routing blackholes during IGP changes, but it does not protect the LDP session itself from going down due to a link outage.

Concept tested. MPLS LDP session protection

Reference. https://www.cisco.com/c/en/us/td/docs/ios/mpls/configuration/guide/12_0sr/mp_12_0sr_book/mp_ldp_sess_prot.html

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