A high-availability virtual IP address (HAVIP) is a private IP address that can be created and released as an independent resource. You can use HAVIPs with high-availability (HA) software such as Keepalived to deploy services in active/standby mode. This improves the availability of your services.

ECS/ENI

Feature release and supported regions

The HAVIP feature is in public preview. To use this feature, submit an application on the Alibaba Cloud Quota Center console.

Important The HAVIP feature is free of charge during the public preview. Alibaba Cloud does not provide service-level agreement (SLA) guarantees during the public preview.
The following table lists the regions that support HAVIPs.
Area Region
Asia Pacific China (Qingdao), China (Beijing), China (Zhangjiakou), China (Hohhot), China (Ulanqab), China (Hangzhou), China (Shanghai), China (Nanjing - Local Region), China (Fuzhou - Local Region), China (Shenzhen), China (Heyuan), China (Guangzhou), China (Chengdu), China (Hong Kong), Japan (Tokyo), South Korea (Seoul), Singapore, Australia (Sydney), Malaysia (Kuala Lumpur), Indonesia (Jakarta), Philippines (Manila), Thailand (Bangkok), and India (Mumbai)
Europe & Americas Germany (Frankfurt), UK (London), US (Silicon Valley), and US (Virginia)
Middle East UAE (Dubai)

Features

Each Elastic Compute Service (ECS) instance is assigned a private IP address as the primary IP address. You can associate HAVIPs with an ECS instance to increase the number of private IP addresses available for the ECS instance. Both the primary IP address and HAVIPs of an ECS instance can be used to establish connections. In addition, you can use HAVIPs with HA software such as Keepalived to deploy services in active/standby mode. This improves the availability of your services. For more information, see Implement high availability by using HAVIPs and keepalived. You can associate an HAVIP with ECS instances by using the following methods:
  • Directly associate an HAVIP with ECS instances.

    Each HAVIP can be associated with multiple ECS instances. After an HAVIP is associated with ECS instances, one ECS instance can send Address Resolution Protocol (ARP) messages to advertise the HAVIP. Then, the ECS instance serves as the primary instance, and the other ECS instances serve as secondary instances. If the primary ECS instance is down, a secondary ECS instance takes over to provide services. You can associate one HAVIP with at most 10 ECS instances.

  • Associate an HAVIP with the primary elastic network interfaces (ENIs) or secondary ENIs of ECS instances.

    If you associate an HAVIP with the primary ENIs or secondary ENIs of multiple ECS instances, one ENI can send ARP messages to advertise the HAVIP. Then, the ENI serves as the primary ENI, and the other ENIs serve as secondary ENIs. If the primary ENI is down, a secondary ENI takes over to provide services. You can associate one HAVIP with the primary or secondary ENIs of at most 10 ECS instances.

HAVIPs provide the following features:
  • HAVIPs are private IP addresses that are not statically assigned to ECS instances or ENIs. HAVIPs can be associated with or disassociated from ECS instances or ENIs through ARP announcements.
  • HAVIPs can be associated with ECS instances or ENIs that belong to the same vSwitch.
  • You can associate each HAVIP with at most 10 ECS instances or 10 ENIs. However, you cannot associate an HAVIP with an ECS instance and an ENI at the same time.

Scenarios

HAVIPs support flexible configurations in the following scenarios:
  • Scenario 1: Internal-facing HA services

    In the following figure, two ECS instances are associated with the same HAVIP. Keepalived is configured for the ECS instances to provide an internal-facing HA service. Other instances in the same virtual private cloud (VPC) can access the service. The HAVIP serves as the service address. If the primary ECS instance is down, the secondary ECS instance takes over. This improves the availability of your services.

    Scenario 1
  • Scenario 2: Internet-facing HA services

    In the following figure, two ECS instances are associated with the same HAVIP. Keepalived is configured and the HAVIP is associated with an elastic IP address (EIP) for the ECS instances to provide an Internet-facing HA service. The EIP that is associated with the HAVIP serves as the service address. If the primary ECS instance is down, the secondary ECS instance takes over. This improves the availability of your services.

    Scenario 2

Limits

Item Limit Adjustable
Network types that support HAVIPs VPCs No
Maximum number of HAVIPs that can be associated with each ECS instance 5
Maximum number of ECS instances or ENIs that can be associated with each HAVIP 10
Whether HAVIPs support broadcasting and multicasting Not supported
Note HAVIPs support only unicasting. To implement high availability by using third-party software such as keepalived, you must modify the configuration file to change the communication method to unicasting.
Maximum number of HAVIPs that can be created with each Alibaba Cloud account 5
Maximum number of HAVIPs that can be created in each VPC 5
Maximum number of route entries that point to an HAVIP in each VPC 5
You can request a quota increase by using one of the following methods:

Use HAVIPs

For more information, see Create and manage an HAVIP.