Creating a VPC Peering Connection to Connect Two VPCs in the Same Account

Scenarios

Two VPCs from the same region cannot communicate with each other by default, but you can use a VPC peering connection to connect them.

The following describes how to create a VPC peering connection to connect two VPCs (vpc-A and vpc-B in this example) in the same account. In this way, instances (ECS-A01 and RDS-B01 in this example) in the two VPCs can communicate with each other.

The procedure is as follows:

Step 1: Create a VPC Peering Connection

Step 2: Add Routes for the VPC Peering Connection

Step 3: Verify Network Connectivity

Figure 1 Connecting two VPCs in an account using a VPC peering connection

Currently, VPC peering connections are free.

Notes and Constraints

• Only one VPC peering connection can be created between two VPCs at the same time.
• A VPC peering connection can only connect VPCs in the same region.
  • If you only need a few ECSs in different regions to communicate with each other, you can assign and bind EIPs to the ECSs.
• If the local and peer VPCs have overlapping CIDR blocks, the VPC peering connection may not be usable.

Prerequisites

You have two VPCs from the same account in the same region. If you want to create one, see Creating a VPC and Subnet.

Step 1: Create a VPC Peering Connection

1. Go to the VPC peering connection list page.
2. In the upper right corner of the page, click Create VPC Peering Connection.

   The Create VPC Peering Connection page is displayed.

3. Configure the parameters as prompted.

   For details, see Table 1.

   Figure 2 Creating a VPC peering connection
   

   Table 1 Parameters for creating a VPC peering connection

   Parameter	Description	Example Value
   Name	Mandatory Enter a name for the VPC peering connection. The name can contain a maximum of 64 characters, including letters, digits, hyphens (-), and underscores (_).	peering-AB
   VPC Peering Connection Name	Mandatory Enter a name for the VPC peering connection. The name can contain a maximum of 64 characters, including letters, digits, hyphens (-), and underscores (_).	peering-AB
   Local VPC	Mandatory VPC at one end of the VPC peering connection. You can select one from the drop-down list.	vpc-A
   Local VPC CIDR Block	CIDR block of the selected local VPC	172.16.0.0/16
   Account	Mandatory Options: My account and Another account Select My account.	My account
   Peer Project	The project is selected in by default if Account is set to My account. In this example, vpc-A and vpc-B are created in region A, and the corresponding project of the account in region A is selected by default.	ab-cdef-1
   Peer VPC	This parameter is mandatory if Account is set to My account. VPC at the other end of the VPC peering connection. You can select one from the drop-down list.	vpc-B
   Peer VPC CIDR Block	CIDR block of the selected peer VPC. If the local and peer VPCs have overlapping CIDR blocks, the VPC peering connection may not be usable. For details, see VPC Peering Connection Usage Examples.	172.17.0.0/16
   Description	Optional Enter a description of the VPC peering connection in the text box as required.	peering-AB connects vpc-A and vpc-B.

4. Click Create Now.

   A dialog box for adding routes is displayed.

5. In the displayed dialog box, click Add Now. On the displayed page about the VPC peering connection details, go to Step 2: Add Routes for the VPC Peering Connection to add a route.

Step 2: Add Routes for the VPC Peering Connection

1. In the lower part of the VPC peering connection details page, click Add Route.

   The Add Route dialog box is displayed.

2. Add routes to the route tables as prompted.

   Table 2 describes the parameters.

   Table 2 Parameter description

   Parameter	Description	Example Value
   VPC	Select a VPC that is connected by the VPC peering connection.	vpc-A
   Route Table	Select the route table of the VPC. The route will be added to this route table. Each VPC comes with a default route table to control the outbound traffic from the subnets in the VPC. In addition to the default route table, you can also create a custom route table and associate it with the subnets in the VPC. Then, the custom route table controls outbound traffic of the subnets. If there is only the default route table in the drop-down list, select the default route table. If there are both default and custom route tables in drop-down list, select the route table associated with the subnet connected by the VPC peering connection.	rtb-vpc-A (Default)
   Destination	An IP address or address range in the VPC being connected by the VPC peering connection. The value can be a VPC CIDR block, subnet CIDR block, or ECS IP address. For details about the route configuration example, see VPC Peering Connection Usage Examples.	vpc-B CIDR block: 172.17.0.0/16
   Next Hop	The default value is the current VPC peering connection. You do not need to specify this parameter.	peering-AB
   Description	Supplementary information about the route. This parameter is optional. The description can contain a maximum of 255 characters and cannot contain angle brackets (< or >).	Route from vpc-A to vpc-B
   Add a route for the other VPC	If you select this option, you can also add a route for the other VPC connected by the VPC peering connection. To enable communications between VPCs connected by a VPC peering connection, you need to add both forward and return routes to the route tables of the VPCs. For details, see VPC Peering Connection Usage Examples.	Selected
   VPC	By default, the system selects the VPC connected by the VPC peering connection. You do not need to specify this parameter.	vpc-B
   Route Table	Select the route table of the VPC. The route will be added to this route table. Each VPC comes with a default route table to control the outbound traffic from the subnets in the VPC. In addition to the default route table, you can also create a custom route table and associate it with the subnets in the VPC. Then, the custom route table controls outbound traffic of the subnets. If there is only the default route table in the drop-down list, select the default route table. If there are both default and custom route tables in drop-down list, select the route table associated with the subnet connected by the VPC peering connection.	rtb-vpc-B (Default)
   Destination	An IP address or address range in the other VPC connected by the VPC peering connection. The value can be a VPC CIDR block, subnet CIDR block, or ECS IP address. For details about the route configuration example, see VPC Peering Connection Usage Examples.	vpc-A CIDR block: 172.16.0.0/16
   Next Hop	The default value is the current VPC peering connection. You do not need to specify this parameter.	peering-AB
   Description	Supplementary information about the route. This parameter is optional. The description can contain a maximum of 255 characters and cannot contain angle brackets (< or >).	Route from vpc-B to vpc-A.

3. Click OK.

   You can view the routes in the route list.

Step 3: Verify Network Connectivity