An Elastic IP address is a public IP address resource that you can purchase and hold independently. You can associate Elastic IP addresses with Elastic Compute Service (ECS) instances of the Virtual Private Cloud (VPC) network, private Server Load Balancers (SLBs) of the VPC network, secondary Elastic Network Interfaces (ENIs) of the VPC network, NAT Gateways, or High-Availability Virtual IP Addresses (HaVips).

An Elastic IP address is also a type of NAT IP address that is located in the public network gateway of Alibaba Cloud, and is mapped to the associated cloud instance through NAT. After a cloud instance is associated with an Elastic IP address, the cloud instance can communicate over the Internet through the Elastic IP address.

The differences between an Elastic IP address and an ECS public IP address

The following table lists the differences between an Elastic IP address and an ECS public IP address.

Item Elastic IP address ECS public IP address
Supported networks VPC VPC and classic network
Can the IP address be independently used? 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 the Cut-Through Mode or Multi-EIP to ENI Mode.

Classic Network: Yes

VPC: No

Benefits

Elastic IP addresses have the following advantages:
  • Purchase and hold independently

    You can purchase an Elastic IP address as an independent resource instead of purchasing it together with other computing or storage resources.

  • Flexible association

    When you need an instance to access the Internet, you can associate an Elastic IP address with the instance. You can also disassociate and release the Elastic IP address at any time.

  • Configurable network capabilities

    You can adjust the bandwidth value of an Elastic IP address as needed. The bandwidth change takes effect immediately.