When you need to connect networks in Google Cloud, three options come up regularly: Shared VPC, VPC Peering, and Cloud VPN. They solve different problems, and knowing which one to reach for is a core competency the Associate Cloud Engineer exam tests directly. Shared VPC vs VPC Peering vs Cloud VPN is a three-way comparison where the right answer depends entirely on what you are connecting and why.
Shared VPC lets one project, called the host project, share its VPC network and subnets with other projects in the same Google Cloud organization, called service projects. Resources in service projects can use the subnets defined in the host project's VPC as if those subnets were their own.
The benefit is centralized management. Instead of each project maintaining its own network configuration, firewall rules, and IP ranges, a network team manages the host project's VPC once. All service projects inherit that network structure. Security policies and IP ranges are consistent across the organization.
Shared VPC requires both the host project and service projects to be in the same organization. A user needs the Shared VPC Admin role to configure the sharing. Once set up, service projects can deploy Compute Engine VMs, GKE clusters, or other resources onto subnets in the host VPC. Resources across service projects communicate over internal IP addresses without traversing the public internet.
Use Shared VPC when you have multiple projects within an organization that need consistent network governance. Large organizations with separate projects for development, staging, and production, or for separate teams or products, often use Shared VPC to avoid duplicating network configuration across every project. The centralized model also makes security auditing easier because all network policy lives in one place.
VPC Peering connects two separate VPC networks so they can communicate using internal IP addresses, without traffic going over the public internet. Unlike Shared VPC, peered VPCs remain independently managed. Each VPC has its own subnets, firewall rules, and routing configuration. Peering just establishes a private communication path between them.
One practical advantage of VPC Peering is that connected VPCs do not need to be in the same organization. You can peer VPCs across different Google Cloud organizations or between different Google Cloud accounts. This makes VPC Peering useful when two separate companies or teams need private connectivity between their respective GCP environments.
VPC Peering does not support transitive routing. If VPC A is peered with VPC B, and VPC B is peered with VPC C, traffic from VPC A cannot reach VPC C through VPC B. Each peering relationship is direct and bilateral. This is worth knowing for the exam because it rules out VPC Peering in scenarios that require hub-and-spoke or transitive connectivity across more than two VPCs.
Use VPC Peering when you have two independently managed VPCs that need to communicate privately, whether they are in the same organization or different ones.
Cloud VPN extends your GCP VPC to networks that live entirely outside of Google Cloud. This includes on-premises data centers, remote office networks, or VPCs in other cloud providers like AWS or Azure. Cloud VPN creates an encrypted tunnel between your GCP VPC and the external network, allowing traffic to flow securely without being exposed in plaintext over the public internet.
The three main Cloud VPN use cases are hybrid connectivity (linking an on-premises data center to GCP), multi-cloud connectivity (linking a GCP VPC to a VPC in another cloud provider), and remote office connectivity (giving a branch office access to GCP resources). In each case, the defining characteristic is that the other network exists outside of GCP, which rules out Shared VPC and VPC Peering as options.
Cloud VPN has throughput and latency constraints compared to the direct internal paths that Shared VPC and VPC Peering use. For organizations with high-bandwidth requirements between on-premises and GCP, Cloud Interconnect is the dedicated-line alternative. But Cloud VPN is the more accessible option for most connectivity needs and is more commonly tested on the Associate Cloud Engineer exam.
The decision follows from what you are connecting. If you are connecting multiple projects within the same GCP organization and want centralized network management, use Shared VPC. If you are connecting two independent VPCs that may or may not be in the same organization, use VPC Peering. If you are connecting a network that lives outside of GCP, whether on-premises or in another cloud provider, use Cloud VPN.
For the ACE exam, the scenario will usually specify the relationship between the networks clearly enough to identify the right answer. Watch for keywords: same organization with multiple projects points to Shared VPC, two separate VPCs that need private connectivity points to VPC Peering, on-premises or another cloud provider points to Cloud VPN.
The GCP Study Hub Associate Cloud Engineer course covers GCP networking in depth, including VPC configuration, firewall rules, Private Google Access, and how connectivity options like Shared VPC, VPC Peering, and Cloud VPN are tested on the ACE exam.
