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Difficulty: MediumConfiguring Network Topology and VPC Infrastructure

A multinational organization operates a hybrid cloud network using a single Google Cloud Virtual Private Cloud (VPC) with subnets in us-central1 and europe-west1. The organization maintains a Dedicated Interconnect connection at a colocation facility in Frankfurt, which connects to a Cloud Router in europe-west1. Administrators observe that on-premises systems in Europe can successfully communicate with Compute Engine instances in europe-west1, but cannot reach instances located in us-central1. How should the Cloud Architect resolve this connectivity issue?

  1. Change the VPC network dynamic routing mode from Regional to Global.Answer
  2. B
    Create a VPC Network Peering connection between the us-central1 subnet and the europe-west1 subnet to route transit traffic across regions.
  3. C
    Deploy an HA VPN tunnel between us-central1 and europe-west1 because Cloud Routers cannot propagate BGP routes multi-regionally over Interconnect.
  4. D
    Configure control plane authorized networks on the europe-west1 Cloud Router to include the us-central1 subnet IP range.

Answer

Change the VPC network dynamic routing mode from Regional to Global.
In Google Cloud VPC networks, dynamic routing mode can be set to Regional or Global. Under Regional dynamic routing, a Cloud Router only advertises subnets located in its local region. By changing the dynamic routing mode to Global, the Cloud Router in europe-west1 will advertise all subnets in the VPC—including us-central1—to the on-premises BGP peer over the Dedicated Interconnect.

Step-by-Step Solution

1
Analyze the current Cloud Router and VPC network routing behavior.
By default, VPC networks often use Regional Dynamic Routing, where Cloud Routers only advertise subnets in their local region to BGP peers.
Understanding why the Cloud Router in europe-west1 is only advertising the local europe-west1 subnet range to the on-premises router.
2
Evaluate the requirement for cross-region hybrid network accessibility.
The requirement states that on-premises systems connected via Interconnect in Europe must reach resources in us-central1.
Global Dynamic Routing enables Cloud Routers in one region to advertise all subnets across the entire VPC to on-premises peers.
3
Modify the VPC dynamic routing configuration.
Updating dynamic routing mode to Global ensures seamless multi-region reachability without deploying extra network infrastructure.
This provides high-availability inter-region routing managed automatically by Google Cloud's software-defined network.

Key Concept

Cloud Router Global Dynamic Routing Mode
Estimated Time:1m 30s
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Topics

Configuring Network Topology and VPC Infrastructure

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