By default, virtual private clouds (VPCs) are isolated. Use a VPC Peering Connection or Cloud Enterprise Network (CEN) to establish private connections between them, allowing instances to communicate across VPCs.
Connection methods
Consider the following factors when choosing a connection method:
Scale: Use a VPC Peering Connection for simple networks with two or three VPCs. For larger networks, use Cloud Enterprise Network (CEN).
Features: If you need advanced features such as multicast, service chaining, or cross-region QoS, or if you want to avoid manual route configuration, use CEN.
Cost: For connecting VPCs within the same region, a VPC Peering Connection is more cost-effective because intra-region connections are free.
Bandwidth: For high-bandwidth intra-region connections, a VPC Peering Connection is the better choice because it has no bandwidth limit.
The following table compares the two solutions.
Item
VPC Peering Connection
Cloud Enterprise Network (CEN)
Connection mode
A full-mesh topology where a peering connection is established between each pair of VPCs.
A hub-and-spoke topology where VPCs connect to a central Transit Router (TR).
Number of VPCs
By default, a VPC can connect to 10 intra-region VPCs and 20 inter-region VPCs.
A single Transit Router (TR) can connect up to 1,000 VPCs by default.
Route configuration
You must manually configure routes for each VPC.
Automatically configures routes using route learning and route synchronization.
Scalability
Low
A VPC supports a limited number of peering connections. Each new VPC requires you to create new connections and manually configure routes.
High
A single TR supports a large number of VPCs. When you add a new VPC, you only need to connect it to the TR without manually configuring routes.
Bandwidth
Intra-region: Unlimited.
Inter-region: 1,024 Mbps by default.
Intra-region: See Maximum bandwidth supported by connections.
Inter-region: If you select the pay-by-data-transfer billing method, the bandwidth is limited by a quota. If you allocate bandwidth from a bandwidth plan, the maximum bandwidth is the size of the bandwidth plan.
Billing
Intra-region connections are free. For inter-region connections, Cloud Data Transfer (CDT) charges fees for outbound data transfer.
Intra-region: connection fees and traffic processing fees. Inter-region: connection fees, traffic processing fees, and inter-region bandwidth fees. For more information, see CEN billing.
Use cases
Connect ECS instances in two VPCs
To connect Elastic Compute Service (ECS) instances in two different VPCs, use a VPC Peering Connection.
Unlike Cloud Enterprise Network (CEN), connecting VPCs within a region is free.
Connect multiple VPCs
Connecting three or more VPCs with VPC Peering Connections is complex because it requires establishing a connection between each pair of VPCs and manually configuring routes.
In this scenario, we recommend that you use Cloud Enterprise Network (CEN). You only need to connect each VPC to a TR in the same region to enable network communication.
Build a cost-effective hybrid network
For complex network architectures, a single connectivity solution may not meet all requirements for scalability, high bandwidth, and cost control. In such cases, use a hybrid approach that combines VPC Peering Connection and Cloud Enterprise Network (CEN).
For example, consider a company that has deployed multiple VPCs across different regions. The company wants to enable communication between these VPCs, implement granular routing policies, and minimize costs.
For intra-region communication, use VPC Peering Connections to connect VPCs at no cost.
For inter-region communication, connect the VPCs to CEN. This enables communication across regions and provides fine-grained control over routing policies.
For specific inter-region connections that require dedicated bandwidth, such as the connection between VPC A and VPC F, use an inter-region VPC Peering Connection.
