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350-501 · Question #631

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…

The correct answer is C. Implement LDP session protection to maintain uptime during outages. 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.

MPLS and Segment Routing

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?

Exhibit

350-501 question #631 exhibit

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.

How the community answered

(31 responses)
  • A
    6% (2)
  • B
    13% (4)
  • C
    77% (24)
  • D
    3% (1)

Why each option

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.

AImplement targeted LDP sessions between the peers connected to interface g0/1 and g0/2.

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.

BImplement MD5 authentication between LDP and OSPF neighbors to secure the connection.

MD5 authentication secures LDP sessions against unauthorized access but does not prevent session termination or improve reliability during link failures.

CImplement LDP session protection to maintain uptime during outages.Correct

LDP session protection enhances reliability by maintaining the LDP session between two neighbors even if the direct link or interface connecting them fails, provided there is an alternative path through the IGP. This prevents the immediate withdrawal of labels and allows traffic to continue flowing over available backup paths, thus improving uptime during outages.

DImplement MPLS LDP sync to synchronize OSPF and LDP.

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

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

Topics

#MPLS LDP#LDP Session Protection#Network Reliability#OSPF Integration

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