Instances in the classic network and VPCs can communicate with each other by using ClassicLink. You can also migrate an instance from the classic network to a virtual private cloud (VPC) and use Cloud Enterprise Network (CEN) to enable the instance to communicate with other instances in other VPCs. This topic describes how to migrate multiple instances from the classic network to a VPC and enable the instances to communicate with other instances in other VPCs.

Prerequisites

Make sure that the instances in the classic network meet the following requirements:

  • The instances are not of instance families that have local disks attached.
  • The instances are not in Hangzhou Zone C where the network type of some ECS instances cannot be changed.
  • All application services required by your business are configured to run on system startup.
  • Check whether the software required by your business is registered based on the MAC addresses of network interface controllers (NICs). After the instances are migrated to a VPC, the public NICs of the instances are removed and the MAC addresses of the NICs are lost. You can contact the software vendor to check whether the software was registered to the MAC addresses of the NICs. If so, you must rebind the NICs to the instances.

Background information

Before you start, make sure that you fully understand the following precautions and limits:
In this topic, the following resources are used:
  • ECS instances in the classic network: ECS-1 and ECS-2
  • An ECS instance in a VPC: ECS-3
  • A VPC created in the migration plan: VPC-1
  • The VPC to which the ECS-3 instance belongs: VPC-2
Perform the following steps to connect the instances:
  1. Create a migration plan to migrate the instances from the classic network to a VPC.
  2. Use Cloud Enterprise Network (CEN) to enable instances in VPC-1 and VPC-2 to communicate with each other.

The VPCs used in this tutorial belong to the same account and region. Therefore, you do not need to configure features such as cross-region interconnection of CEN. If you want to configure cross-account or cross-region communication, you can also use CEN. For more information, see CEN.

If your resources are in the same account and region and are not frequently accessed, you do not need to migrate your classic network-type resources to VPCs. You can use the ClassicLink feature to enable communication between resources in the classic network and VPCs. For more information, see Connect a classic network to a VPC.

Step 2: Migrate the instances from the classic network to a VPC

Create a migration plan to migrate the ECS-1 and ECS-2 instances from the classic network to VPC-1. You can create a VPC in the migration plan. For example, you can set Destination VPC to ID/Name: (Default) Automatically create a VPC CIDR block: 10.0.0.0/8.

For more information, see Migrate ECS instances from the classic network to a VPC.

Step 2: Create a CEN instance and attach the VPCs to the CEN instance

After the instances are migrated to VPC-1, perform the following steps to enable communication between VPC-1 and VPC-2:

  1. Log on to the CEN console.
  2. Click Create CEN Instance.
  3. In the Attach Network section, complete the following configurations:
    • Network Type: Select VPC.
    • Region: Select the same region as VPC-1. Example: China (Shanghai).
    • Networks: Select VPC-1 created in Step 1.
  4. After you configure the other parameters, click OK.
    For more information, see Create a CEN instance.
  5. Log on to the VPC console.
  6. In the top navigation bar, select the region of VPC-2 to which the ECS-3 instance belongs.
  7. Find VPC-2, click its name to go to the VPC Details page.
  8. Click Attach to CEN and select the created CEN instance from the drop-down list.

Step 3: Test the connectivity

After the preceding steps are performed, the ECS-1, ECS-2, and ECS-3 instances can communicate with each other. The ECS-1 and ECS-2 instances are migrated to the same VPC, and can communicate with each other over the internal network. You only need to connect to the ECS-3 instance in VPC-2 and run the following command to check whether the instance can communicate with the other two instances: 
ping <Private IP address of the instance>
For example, run the ping 10.0. **. ** command. If a command output similar to the following figure is returned, the instance can communicate with the other two instances.ping