What Are the Differences Between EIP, Private IP Address, and Virtual IP Address?

Private IP address

Private IP addresses come with your ECSs and belong to the VPC subnets of the ECSs. They are used for private communication on the cloud.

• Private IP address of ECS-A-01: 172.16.0.84
• Private IP address of ECS-B-01: 172.16.1.12

Virtual IP address

A virtual IP address can be shared among multiple ECSs. Two ECSs can work as an active and standby pair to achieve high availability by using a virtual IP address and Keepalived. If the active ECS is faulty, the virtual IP address can be dynamically switched to the standby ECS to continue providing services.

For more information about virtual IP addresses, see Virtual IP Address Overview. For details about how to set up a high availability cluster, see Building Highly Available Web Server Clusters with Keepalived.

Bind virtual IP address (172.16.0.2) both ECS-A-01 and ECS-A-02. The active/standby switchover of ECS-A-01 and ECS-A-02 can be implemented by using Keepalived.

EIP

EIPs allow cloud resources to access the Internet. They can be flexibly bound to or unbound from instances.

• You can bind an EIP to a virtual IP address to enable the ECSs with the virtual IP address bound to access the Internet.
• You can also bind an EIP to the ECSs to enable them to access the Internet.

For more information, see EIP Overview.

• Bind EIP (122.9.9.85) to virtual IP address (172.16.0.2) to enable ECS-A-01 and ECS-A-02 to access the Internet.
• Bind EIP (122.9.9.87) to ECS-B-01 to enable ECS-B-01 to access the Internet.