Modifying the VPC CIDR Block

Scenarios

If you use a cloud connection together with another cloud service, such as NAT Gateway, Direct Connect, or VPN, you need to add the CIDR block of the cloud service to the cloud connection, so that the VPCs you load to the cloud connection can communicate with that cloud service.

Precautions

Modifying the VPC CIDR block may affect the communication between the cloud connection and external networks. Exercise caution when performing this operation.

When you load a VPC to a cloud connection, you can select the subnets in the VPC and specify custom CIDR blocks.

Only the subnets you select and the custom CIDR blocks you specify can be used for communication.

The following uses an example to explain this.

Suppose that there are two VPCs (VPC-A and VPC-B), each in a separate region. A cloud connection has been created to enable communication between the two VPCs. VPC-A has two subnets: subnet 1 and subnet 2. If only subnet 1 is selected when VPC-A is loaded to the cloud connection, only subnet 1 can communicate with VPC-B, and subnet 2 cannot communicate with VPC-B. To enable communication between subnet 2 in VPC-A and VPC-B, you need to select subnet 2 and deselect subnet 1 for VPC-A. In this way, subnet 2 can communicate with VPC-B, and subnet 1 cannot communicate with VPC-B.

Procedure

1. Go to the Cloud Connections page.
2. Click the name of the cloud connection to go to the Basic Information page.
3. Click the Network Instances tab.
4. Locate the VPC for which you want to add custom CIDR blocks.
5. In the lower right area of the page, click Modify VPC CIDR Block.
6. Modify the subnets and custom CIDR blocks.
7. Click OK.