A virtual private cloud (VPC) is a private network dedicated for your use. You have full control over your VPC. For example, you can specify the CIDR block and configure route tables and gateways. In a VPC, you can deploy Alibaba Cloud resources, such as Elastic Compute Service (ECS) instances, ApsaraDB RDS instances, and Server Load Balancer (SLB) instances.
Furthermore, you can connect your VPC to other VPCs or on-premises networks through Express Connect circuits to create a custom network environment. This way, you can migrate applications to the cloud and extend data centers.
Each VPC consists of at least one private CIDR block, a vRouter, and at least one vSwitch.
Private CIDR blocks
When you create a VPC and a vSwitch, you must specify the private IP address range for the VPC in CIDR notation.
You can use one of the standard private CIDR blocks listed in the following table or their subnets as the private CIDR block of a VPC, or use a custom CIDR block. For more information, see Plan networks.
CIDR blocks Description 192.168.0.0/16 Number of available private IP addresses (excluding IP addresses reserved by the system): 65,532 172.16.0.0/12 Number of available private IP addresses (excluding IP addresses reserved by the system): 1,048,572 10.0.0.0/8 Number of available private IP addresses (excluding IP addresses reserved by the system): 16,777,212 Custom CIDR block Custom CIDR blocks except 100.64.0.0/10, 126.96.36.199/4, 127.0.0.0/8, 169.254.0.0/16, and their subnets
A vRouter is the hub of a VPC. As a core component, it connects the vSwitches in a VPC and serves as a gateway between a VPC and other networks. After a VPC is created, a vRouter is automatically created for the VPC. Each vRouter is associated with a route table.
For more information, see Route table overview.
A vSwitch is a basic network component that connects different cloud resources in a VPC. After you create a VPC, you can create vSwitches to divide the VPC into one or more subnets. vSwitches deployed in a VPC can communicate with each other over the private network. You can deploy your applications in vSwitches that belong to different zones to improve service availability.
For more information, see vSwitches.