Virtual IP Address Usage Guidelines

A virtual IP address is a private IP address that can be independently assigned from and released to a VPC subnet. You can:

• Bind one or more virtual IP addresses to a cloud server so that you can use either the virtual IP address or private IP address to access the server. If you have multiple services running on a cloud server, you can use different virtual IP addresses to access them.

• Bind a virtual IP address to multiple cloud servers. You can use a virtual IP address and an HA software (such as Keepalived) to set up a high-availability active/standby cluster. If you want to improve service availability and eliminate single points of failure, you can deploy cloud servers in the active/standby pair or deploy one cloud server and multiple standby cloud servers. In this case, the cloud servers can use the same virtual IP address. If the active cloud server goes down, the standby cloud server becomes the active server and continues to provide services.

Application Scenarios

• Using a Virtual IP Address and Keepalived to Set Up a High-Availability Cluster
• Using a Virtual IP Address and Keepalived/LVS to Set Up a High-Availability Load Balancing Cluster

Common Operations

• Assigning a Virtual IP Address
• Binding a Virtual IP Address to an Instance or EIP
• Unbinding a Virtual IP Address from an Instance or EIP
• Releasing a Virtual IP Address

Figure 1 shows a high-availability web cluster using Keepalived. In this architecture, virtual IP address 192.168.0.177 is bound to ECS-HA1 and ECS-HA2. To allow ECS-HA1 and ECS-HA2 to access and be accessed from the Internet, an EIP (EIP-A) is bound to the virtual IP address. They work as follows:

1. ECS-HA1 works as the active ECS and provides services accessible from the Internet using EIP-A. ECS-HA2 works as the standby ECS, with no services deployed on it.
2. If ECS-HA1 goes down, ECS-HA2 takes over services, ensuring service continuity.