Build a ClassicLink connection

You can set up a ClassicLink connection to let the ECS instance of the classic network access the resources deployed in a VPC network.

1. Log on to the VPC console.
2. Select the region of the target VPC, and click the ID of the target VPC.
3. On the VPC Details page, click Enable ClassicLink. In the displayed dialog box, click OK.
4. Go to the ECS console.
5. In the left-side navigation pane, click Instances.
6. Select a region, and then locate the target classic ECS instance.
7. Click More > Network and Security Group > Connect to VPC.
8. In the displayed dialog box, select the target VPC and click OK. Then click the security group configuration link.
   
   
   
9. Click Add ClassicLink Rules and configure the security rule according to the following information. Then, click OK.

   Configuration	Description
   Classic Security Group	Display the classic network security group.
   Select VPC Security Group	Select a security group to use. Up to 5 security groups can be selected.
   Mode	Select one of the following modes: Classic &lt;=> VPC: The connected resources can access each other (recommended). Classic => VPC: Authorize the classic ECS instance to access cloud resources in the connected VPC. Classic <= VPC: Authorize the cloud resources in the connected VPC to access the classic ECS instance.
   Protocol Type and Port Range	Select the protocol and port used for the communication. The port must be in the form of xx/xx.  For example, if port 80 is used, enter 80/80.
   Priority	Set the priority for the rule.  A smaller number represents a higher priority.
   Description	Enter a description for the security rule.

10. On the ECS instances page, click the Column Filter icon on the upper-right corner, and then select the Connection Status check box. Click OK.