How to Configure Shared VPC Interconnect for 99.9% SLA?

PCNE By islever Editorial Last updated

Short answer

B Create two Interconnect connections in different edge availability domains of the co-location facility in a project that will contain your connections. Create one VLAN attachment for each physical Cloud Interconnect connection and a single Cloud Router in the Shared VPC host project.

Question

Your organization is connecting their Shared VPC network to their on-premises data center by using Dedicated Interconnect to provide connectivity to all of its service projects. You need to create a design to configure your VLAN attachments and Cloud Routers. You also want to achieve a 99.9% Cloud Interconnect SLA based on Google Cloud s reference design. What should you do?
  1. Create two Cloud Interconnect connections in different edge availability domains of two different co-location facilities in a project that will contain your connections. Create one VLAN attachment and Cloud Router for each physical interconnect in the Shared VPC host project.
  2. Create two Interconnect connections in different edge availability domains of the co-location facility in a project that will contain your connections. Create one VLAN attachment for each physical Cloud Interconnect connection and a single Cloud Router in the Shared VPC host project. Correct Answer
  3. Create two Cloud Interconnect connections in different edge availability domains of the co-location facility in a project that will contain your connections. Create one VLAN attachment for each physical interconnect and a single Cloud Router in the service projects.
  4. Create two Cloud Interconnect connections in different edge availability domains of the co-location facility in a project that will contain your connections. Create a Cloud Router in the Shared VPC host project and the VLAN attachments in the Shared VPC service projects.

Key Takeaways

This question tests your familiarity with Google’s 99.9% availability reference architecture, where the common trap is over-engineering by deploying multiple Cloud Routers or misplacing network resources in service projects.

Achieving a 99.9% SLA for Shared VPC Dedicated Interconnect requires redundant physical links across different edge availability domains within a single co-location facility. Community consensus aligns with Google’s official reference design, which mandates a single Cloud Router in the host project managing one VLAN attachment per physical connection.

Common mistake: Option A is the most frequent incorrect choice, driven by the misconception that high availability requires redundant Cloud Routers; in reality, a single router supports Equal-Cost Multi-Path routing across both attachments, satisfying the SLA without extra overhead.

Expert Analysis

Why the Answer Is Correct

Option B perfectly matches Google’s official 99.9% SLA reference design for Dedicated Interconnect. By provisioning two physical connections in distinct edge availability domains within the same co-location facility, you ensure hardware and path redundancy. Each connection gets its own VLAN attachment, allowing the single Cloud Router in the Shared VPC host project to perform ECMP routing, which distributes traffic optimally while meeting the uptime requirement.

Why the Other Options Are Wrong

Option A unnecessarily creates two Cloud Routers, which adds complexity without improving the SLA since one router already handles dual attachments via ECMP. Option C incorrectly places the Cloud Router in service projects, violating Shared VPC networking principles where routing infrastructure must reside in the host project. Option D splits configuration responsibilities between host and service projects, which contradicts Google’s centralized management model for interconnects and breaks the standardized reference design.

Community Comment Notes

Comment [1] strongly validates Option B and directly references Google’s official tutorial, confirming that two routers are not required for this topology. Comment [2] reinforces the key architectural constraints, emphasizing that redundant interconnects must share a co-location facility while maintaining a single host-project router. Comment [3] advocates for Option A but lacks supporting evidence against the official documentation, highlighting a common exam pitfall where intuition overrides documented best practices.

Official Reference

https://cloud.google.com/network-connectivity/docs/interconnect/tutorials/dedicated-creating-999-availability

This link opens the official vendor documentation in a new tab.

Exam Strategy

Always cross-reference PCNE questions with Google’s official reference architectures and tutorials before relying on intuition. Remember that Shared VPC networking resources like Cloud Routers and VLAN attachments must be created in the host project, and single routers can leverage ECMP to satisfy redundancy and SLA requirements without duplication.

Community Votes

B
80%
A
20%

80% of anonymous learners picked answer B. Votes are pick records left by other test-takers — they are not the verified answer.

Discussion 3 contributions

Compiled from public community threads and reader submissions, lightly edited for clarity. Handles and vote tallies are shown as recorded, and comments reflect the views of individual contributors.

From public community threads 3

  1. 1f01b87 👍 3 Answered B
    B is the correct answer. No need to create 2 cloud routers. https://cloud.google.com/network-connectivity/docs/interconnect/tutorials/dedicated-creating-999-availability#creating_a_999_topology
  2. mohitms1996 👍 1 Answered B
    Your goal is to configure Dedicated Interconnect to connect your Shared VPC to the on-premises data center while achieving a 99.9% SLA based on Google's reference design. Key Requirements for 99.9% SLA: Redundant Interconnects: You must have two Cloud Interconnect connections in different edge availability domains (within the same co-location facility). VLAN Attachments: Each Cloud Interconnect connection must have one VLAN attachment. Cloud Router Placement: A single Cloud Router in the Shared VPC host project is recommended because it simplifies BGP route management for all service projects.
  3. RKS_2021 👍 1 Answered A
    A is correct.

Reader comments & corrections

No reader corrections yet — spotted an error or have a note? Share it below.

Log in to comment, report an error, or add a note about this question.

Submitted for moderation before publishing. Keep it helpful and respectful.

How to Resolve BGP Session Failures on Cloud Interconnect?

S-grade

Deploying Packet Mirroring Policies in GCP Regions

S-grade

Troubleshooting Asymmetric Traffic on Google Cloud Interconnect

S-grade

How to Configure DNS Forwarding Across Isolated VPC Networks?

S-grade

Practice All PCNE Questions

Access 80 questions with complete answers and detailed explanations.

View Full PCNE Practice Test →

← Back to PCNE Study Guide