An elastic IP address (EIP) is a public IP address that you can purchase and use as an independent resource. You can associate EIPs with Elastic Compute Service (ECS) instances, internal-facing Server Load Balancer (SLB) instances, secondary elastic network interfaces (ENIs), NAT gateways, and high-availability virtual IP addresses (HAVIPs). The ECS instances, internal-facing SLB instances, and secondary ENIs must be deployed in virtual private clouds (VPCs).

EIPs are NAT IP addresses deployed on the Internet-facing gateway of Alibaba Cloud, and are mapped to the associated cloud resources through NAT. After EIPs are associated with cloud resources, the cloud resources can use the EIPs to communicate with the Internet.

Differences between an EIP and a static public IP address of an ECS instance

The following table describes the differences between an EIP and a static public IP address of an ECS instance.

Feature EIP Static public IP address
Supported network VPC VPC and classic network
Used as an independent resource Supported Not supported
Associated with and disassociated from an ECS instance at any time Supported Not supported
Displayed in the ENI information of the operating system of the associated ECS instance Cut-through mode: Displayed

Classic network: Displayed

VPC: Not displayed

Line types

EIP supports the line types of BGP (Multi-ISP) and BGP (Multi-ISP) Pro. The following table lists the differences between BGP (Multi-ISP) and BGP (Multi-ISP) Pro.

Item BGP (Multi-ISP) BGP (Multi-ISP) Pro
Advantages BGP (Multi-ISP) provides high-quality and high-bandwidth BGP lines.
  • Up to 89 high-quality BGP lines are available worldwide.
  • Direct connections can be established in all regions of mainland China through lines of the following Internet Service Providers (ISPs): China Telecom, China Unicom, China Mobile, China Mobile Tietong, China Netcom, China Education and Research Network (CERNET), National Radio and Television Administration, Dr. Peng Telecom & Media Group, and Founder Broadband Network.
  • You can use BGP (Multi-ISP) with EIP bandwidth plans to obtain higher bandwidth (up to 100 Gbit/s).
BGP (Multi-ISP) Pro has all the advantages of BGP (Multi-ISP). Compared with BGP (Multi-ISP), when BGP (Multi-ISP) Pro provides services to clients in mainland China (excluding data centers), cross-border connections are established without using international ISP services. This reduces network latency.
Supported regions All regions China (Hong Kong)

Benefits

EIPs have the following benefits:
  • Purchase and use as independent resources

    You can purchase and use an EIP as an independent resource. EIPs are not bundled with other computing or storage resources.

  • Associate with resources at any time

    You can associate EIPs with resources at any time. You can also disassociate EIPs from resources and release the EIPs that you no longer need. This prevents unexpected charges.

  • Modify bandwidth limits on demand

    You can modify the bandwidth limit of an EIP at any time based on your business requirements. The modification immediately takes effect.