This topic provides an overview of Elastic IP Address (EIP). An EIP is a public IP address resource that you can purchase and hold as an independent resource. You can associate an EIP with an Elastic Compute Service (ECS) instance, an internal Server Load Balancer (SLB) instance, or a secondary Elastic Network Interface (ENI) connected to a Virtual Private Cloud (VPC) network. You can also associate an EIP with a NAT gateway, or a High-Availability Virtual IP Address (HAVIP).
An EIP is also a Network Address Translation (NAT) IP address. It is provisioned in the public-facing gateway of Alibaba Cloud and is mapped to the associated cloud resource by using NAT. After an EIP is associated with a cloud resource, the cloud resource can access the public network by using the EIP.
The differences between an EIP and an ECS public IP address
The following table lists the differences between an EIP and an ECS public IP address.
|Item||EIP||ECS public IP address|
|Supported networks||VPC||VPC and classic network|
|Can the IP address be held as an independent resource?||Yes||No|
|Can the IP address be associated with and disassociated from an ECS instance at any time?||Yes||No|
|Can the IP address be read on the ENI of an ECS instance?||The IP address can be read on the ENI in Cut-Through Mode or Multi-EIP to ENI Mode.||
Classic network: Yes
|Item||BGP (Multi-ISP)||BGP (Multi-ISP) Pro|
|Advantages||BGP (Multi-ISP) provides high-quality and high-bandwidth BGP lines.
||BGP (Multi-ISP) Pro has all the advantages of BGP (Multi-ISP). Compared with BGP (Multi-ISP), BGP (Multi-ISP) Pro can be used to establish direct cross-border connections without using international ISP services. This allows to reduce network latency.|
|Supported regions||All regions||China (Hong Kong)|
- 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 associate an EIP with a cloud resource as needed. You can also dissociate and release the EIP at any time. This allows to avoid unexpected payments.
- Configurable network capabilities
You can adjust the maximum bandwidth of an EIP at any time. The bandwidth change takes effect immediately.