Question

Difficulty: MediumConfiguring Network Topology and VPC Infrastructure

An enterprise organization is setting up a hybrid connectivity architecture between an on-premises data center and Google Cloud using Dedicated Interconnect. The architecture uses a single custom-mode VPC network with application subnets deployed in both the us-central1 and europe-west1 regions. Cloud Routers are deployed in both regions to establish BGP sessions with on-premises routers. The lead network architect requires workloads in all GCP regions to dynamically send and receive traffic to and from on-premises through the Interconnect attachments in any region. Which VPC network configuration must be applied to satisfy this requirement?

  1. Set the VPC network dynamic routing mode to Global.Answer
  2. B
    Configure VPC Network Peering between the us-central1 and europe-west1 subnets with custom route export enabled.
  3. C
    Replace the Dedicated Interconnect attachments with HA VPN tunnels in each region to establish mesh routing.
  4. D
    Enable Control Plane Authorized Networks on the Cloud Routers in both regions.

Answer

Set the VPC network dynamic routing mode to Global.
In Google Cloud Networking, a VPC network's dynamic routing mode determines whether dynamic routes learned by Cloud Routers (via BGP over Interconnect or VPN) are available only in the region of the Cloud Router (Regional) or across all regions in the VPC (Global). Setting dynamic routing to Global allows instances in europe-west1 to utilize the Cloud Router and Interconnect located in us-central1, and vice versa.

Step-by-Step Solution

1
Analyze the routing scope requirement for multi-region VPC subnets communicating via BGP.
Identified that by default, Regional Dynamic Routing only shares dynamic routes learned by Cloud Routers with resources in the same region.
Regional dynamic routing restricts dynamic routes to the local region of the Cloud Router.
2
Determine the parameter required to expand dynamic route propagation across all regions within the VPC.
Configuring Global Dynamic Routing allows Cloud Routers in any region to propagate BGP-learned routes to all subnets in the VPC across all regions.
Global dynamic routing enables global visibility of BGP dynamic routes across the entire VPC topology.

Key Concept

VPC Dynamic Routing Modes (Regional vs. Global)
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