This topic provides an overview of Elastic IP Address. An elastic IP address (EIP) is a public IP address that you can purchase and hold as an independent resource. You can associate an EIP with an Elastic Compute Service (ECS) instance deployed in a virtual private cloud (VPC), an internal Server Load Balancer (SLB) instance deployed in a VPC, or a secondary elastic network interface (ENI) attached to a VPC. You can also associate an EIP with a NAT gateway, or a High-Availability Virtual IP Address (HAVIP).
An EIP is also a NAT IP address that is provisioned in a public-facing gateway of Alibaba Cloud and is mapped to the associated cloud resource with NAT. After an EIP is associated with a cloud resource, the cloud resource can connect to the Internet by using this EIP.
Differences between an EIP and a public IP address of an ECS instance
The following table compares the features of an EIP with those of a public IP address of an ECS instance.
|Feature||EIP||ECS public IP address|
|Supported networks||VPC||VPC and classic network|
|Support for being held as an independent resource||Yes||No|
|Support for being associated with and disassociated from an ECS instance at any time||Yes||No|
|Support for being displayed in the ENI information of the associated ECS instance||The IP address is displayed in the ENI information if it is associated with the ENI in the cut-through mode or multi-EIP to ENI mode||
Classic network: Yes
- Independent purchase and possession
You can purchase and hold an EIP as an independent resource. EIPs are not bundled with other computing or storage resources.
- Flexible association
You can dissociate an EIP from a cloud resource and then release the EIP if the EIP is no longer needed. This prevents unexpected charges on your account.
- Configurable network capabilities
You can adjust the peak bandwidth of an EIP at any time. The bandwidth changes take effect immediately.