Alibaba Cloud Elastic Compute Service (ECS) supports the classic network and virtual private clouds (VPCs).
VPCs
A VPC is an isolated virtual network built on Alibaba Cloud. VPCs are logically isolated from each other. You can customize the topology and IP addresses within a VPC. VPCs are suitable for users who have high network security requirements and network management capabilities.
For more information about VPCs, see What is a VPC?
Classic network
Services that use the classic network are deployed in the public infrastructure of Alibaba Cloud, and are planned and managed by Alibaba Cloud. The classic network is suitable for users who have high requirements for network availability.
Differences
The following table describes the differences between VPCs and the classic network.
| Item | VPC | Classic network |
|---|---|---|
| Layer 2 logical isolation | Supported. | Not supported. |
| Custom private CIDR block | Supported. | Not supported. |
| Private IP address planning | Private IP addresses must be unique within a single VPC, but can be duplicate across VPCs. | Private IP addresses must be unique in the classic network. |
| Instance communication within or between private networks | Instances in the same VPC can communicate with each other. However, instances in different VPCs are isolated from each other. | Instances in the classic network can communicate with each other if they belong to the same region and the same account. |
| Tunneling | Supported. | Not supported. |
| Custom router | Supported. | Not supported. |
| Route table | Supported. | Not supported. |
| vSwitch | Supported. | Not supported. |
| SDN | Supported. | Not supported. |
| Self-managed NAT gateway | Supported. | Not supported. |
| Self-managed VPN | Supported. | Not supported. |