This topic provides an overview of the solutions that are used to migrate cloud resources from a classic network to a virtual private cloud (VPC). A VPC is an isolated network environment and ensures high security for your workloads.
A VPC is a private network in Alibaba Cloud. You can use Alibaba Cloud resources in your VPC. VPCs provide the following benefits:
Secure network environment
VPCs isolate the data link layer based on the tunneling technique. VPCs provide an independent, isolated, and secure network for each tenant. Different VPCs are isolated from each other.
Flexible network configurations
You can specify the CIDR blocks and configure route tables and gateways in your VPC. Furthermore, you can connect your VPC to other VPCs or on-premises data centers to create a custom network environment through a physical connection or VPN gateways. This allows you to extend the capacity of on-premises data centers and migrate applications to Alibaba Cloud.
You can use the following solutions to migrate your cloud resources from a classic network to a VPC. You can use either of these solutions or combine them to meet your business requirements.
If your system is deployed on ApsaraDB RDS, Server Load Balancer (SLB), or other cloud services, we recommend that you use the hybrid migration solution. This solution allows you to migrate your system to a VPC without service disruptions.
This solution can be integrated with the ClassicLink feature to allow ECS instances in the classic network to access cloud resources in the VPC. For more information, see Overview.
Single ECS migration
If your applications are deployed on an ECS instance and restarting the instance does not affect your system, we recommend that you use the single ECS migration solution.
The hybrid migration is a seamless migration solution that consists of hybrid access and hybrid attachment. This solution allows you to create cloud instances in a VPC, such as ECS instances, and migrate your applications to the VPC. After all your systems are migrated to the VPC, you can release the cloud resources in the classic network. For more information, see Hybrid migration.
Hybrid attachment refers to attaching ECS instances in classic networks and VPCs to a Server Load Balancer (SLB) instance as backend servers to process forwarded requests. Hybrid attachment also allows you to add ECS instances in the classic networks and the VPC to a VServer group.
Hybrid attachment is supported by public-facing and internal SLB instances.Note You can attach ECS instances in classic networks and VPCs to an internal network SLB instance. If you configure a Layer-4 (TCP and UDP) listener, you can obtain real client IP addresses from the ECS instances in the VPC. However, you cannot obtain IP addresses from ECS instances in the classic network. If you configure a Layer-7 (HTTP and HTTPs) listener, you can obtain the real client IP addresses from ECS instances in the VPC and the classic-network.
Hybrid access allows ApsaraDB RDS, Object Storage Service (OSS), or other cloud services to be accessed by both the ECS instances in the classic network and the ECS instances in the VPC. Each service supports hybrid access and provides two types of endpoints. One type of endpoint is used to access the service over the classic network. The other type of endpoint is used to access the service within the VPC.
When you use the hybrid migration solution, take note of the following rules:
This solution supports most migration scenarios. If the ECS instances in the classic network are required to communicate with the VPC, you can use the ClassicLink feature to enable internal connections among these ECS instances.
This solution applies only to the migration of your system from a classic network to a VPC.