Network

VPC

Virtual Private Cloud (VPC) allows you to create customized virtual networks in your logically isolated AZ. Such networks are dedicated zones that are logically isolated, providing secure network environments for your ECSs. You can define security groups, virtual private networks (VPNs), IP address segments, and bandwidth for a VPC. This facilitates internal network configuration and management and allows you to change your network in a secure and convenient network manner. You can also customize the ECS access rules within a security group and between security groups to improve ECS security.

For more information about VPC, see Virtual Private Cloud User Guide.

Subnets

A subnet is a range of IP addresses in your VPC and provides IP address management and DNS resolution functions for ECSs in it. The IP addresses of all ECSs in a subnet belong to the subnet.

Figure 1 Subnets

By default, ECSs in all subnets of the same VPC can communicate with each other, while ECSs in different VPCs cannot.

Security Group

A security group is a collection of access control rules for ECSs that have the same security protection requirements and that are mutually trusted. By adding an ECS to a security group, you apply all the rules defined for this security group to this ECS.

Your account automatically comes with a default security group. The default security group allows all outbound data, denies all inbound data, and allows all data between ECSs in the group. Your ECSs in the security group can communicate with each other without the need to add rules.

Figure 2 Default security group

Table 1 describes the rules in the default security group.

EIP

The Elastic IP (EIP) service enables your cloud resources to communicate with the Internet using static public IP addresses and scalable bandwidths. EIPs can be bound to or unbound from ECSs, BMSs, virtual IP addresses, NAT gateways or load balancers. Various billing modes are provided to meet different service requirements.

Each EIP can be used by only one cloud resource at a time.

Figure 3 Accessing the Internet using an EIP