Alibaba Cloud ECS provides two network types: Virtual Private Cloud (VPC) and classic network.
VPC
VPC is an isolated virtual network environment built on Alibaba Cloud public cloud. VPCs are logically isolated from each other. You can customize the topology and IP addresses in a VPC. VPC is suitable for users who have high network security requirements and network management capabilities.
For more information, see What is a VPC?.
Classic network
Services that use the classic network are deployed in the public infrastructure of Alibaba Cloud, and planned and managed by Alibaba Cloud. The classic network is suitable for users who have high requirements for network usability.
Note If you purchased your first ECS instance after 12:00:00 (UTC+8) on June 16, 2017, you cannot select the classic network.
Differences
The following table shows 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. | 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. |
| Routing table | Supported. | Not supported. |
| vSwitch | Supported. | Not supported. |
| SDN | Supported. | Not supported. |
| Self-built NAT gateway | Supported. | Not supported. |
| Self-built VPN | Supported. | Not supported. |