Virtual IP Address

A virtual IP address is a private IP address independently assigned from a VPC subnet. It can be released when no longer needed. You can:

• Bind one or more virtual IP addresses to a cloud server so that you can use either the virtual 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 avoid single points of failure, you can deploy cloud servers in the active/standby mode or deploy one active cloud server and multiple standby cloud servers. In this arrangement, the cloud servers all 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.

Generally, cloud servers use private IP addresses for internal communications. Virtual IP addresses provide similar access and support communications within a VPC at Layer 2 and Layer 3, between VPCs with VPC peering connections, between cloud and on-premises networks with VPN or Direct Connect, and Internet access with EIPs. Figure 1 describes how private IP addresses, the virtual IP address, and EIPs work together.

• Private IP addresses are used for internal network communication.
• The virtual IP address works with Keepalived to build an HA cluster. ECSs in this cluster can be accessed through one virtual IP address.
• EIPs are used for Internet communication.