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400-007 · Question #259

A business requirement stating that failure of WAN access for dual circuits into an MPLS provider for a Data Centre cannot happen due to related service credits that would need to be paid has led to…

The correct answer is B. Provision of an additional MPLS provider. Diversely routed circuits to different PoPs of the same provider eliminate local access failures but still expose a single provider as a failure domain. Adding a second MPLS provider is the logical next step to achieve true carrier-level redundancy.

Designing Network Infrastructure

Question

A business requirement stating that failure of WAN access for dual circuits into an MPLS provider for a Data Centre cannot happen due to related service credits that would need to be paid has led to diversely routed circuits to different points of presence on the providers network. What should a network designer also consider as part of the requirement?

Options

  • ADual PSUs & Supervisors on each MPLS router
  • BProvision of an additional MPLS provider
  • COut of band access to the MPLS routers
  • DEnsuring all related remote branches are dual homed to the MPLS network

How the community answered

(44 responses)
  • A
    11% (5)
  • B
    64% (28)
  • C
    20% (9)
  • D
    5% (2)

Why each option

Diversely routed circuits to different PoPs of the same provider eliminate local access failures but still expose a single provider as a failure domain. Adding a second MPLS provider is the logical next step to achieve true carrier-level redundancy.

ADual PSUs & Supervisors on each MPLS router

Dual PSUs and supervisors on MPLS routers address on-premises hardware redundancy but provide no protection against the provider network itself becoming unavailable.

BProvision of an additional MPLS providerCorrect

Even with circuits routed to geographically diverse PoPs, a single MPLS provider remains a single point of failure for major outages, bankruptcy, or provider-wide events. Provisioning a second independent MPLS provider introduces true carrier diversity, ensuring the Data Centre maintains WAN connectivity even if the primary provider suffers a total service failure and service credits must be paid.

COut of band access to the MPLS routers

Out-of-band management access allows engineers to reach routers during outages but does not restore or maintain data-plane connectivity through the MPLS network.

DEnsuring all related remote branches are dual homed to the MPLS network

Dual-homing remote branches improves resilience at branch sites but does not address the core requirement that the Data Centre WAN access must not fail.

Concept tested: MPLS WAN carrier diversity and provider-level redundancy

Source: https://www.cisco.com/c/en/us/td/docs/solutions/Enterprise/WAN_and_MAN/CVD/WAN_Design_Guide.html

Topics

#WAN redundancy#MPLS#provider diversity#dual homing

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