An elastic IP address (EIP) is a public IP address that you can purchase and use as an independent resource. You can associate an EIP with an Elastic Compute Service (ECS) instance, an internal-facing Classic Load Balancer (CLB) instance, an internal-facing Application Load Balancer (ALB) instance, a secondary elastic network interface (ENI), a NAT gateway, or a high-availability virtual IP address (HAVIP). If you want to associate an EIP with an ECS instance, CLB instance, or secondary ENI, make sure that the cloud resource with which you want to associate the EIP is deployed in a virtual private cloud (VPC).
An EIP is a NAT IP address provisioned on the Internet-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 use the EIP to communicate with the Internet.
|Apply for an EIP||Apply for an EIP|
|Create an IP address pool||You can enable the system to allocate an IP address from a specific IP address pool to your EIP. You can create an IP address pool and add a range of IP addresses to the IP address pool. When you apply for an EIP, you can specify an IP address pool. This way, the system allocates an IP address from the IP address pool to the EIP.||Create and manage IP address pools|
|Associate an EIP with a cloud resource|
|Associate an EIP with an EIP bandwidth plan||You can associate an EIP with an EIP bandwidth plan to acquire larger bandwidth. EIP bandwidth plans allow you to manage bandwidth resources in a flexible way.||Associate an EIP with an EIP bandwidth plan|
- When you create an Internet-facing ALB instance, you can enable the system to automatically allocate a public IP address or select an EIP to associate with the ALB instance. For more information, see Create an ALB instance.
- To switch the network type of an ALB instance from internal-facing to Internet-facing, you must associate an EIP with the ALB instance. For more information, see Change the network type of an ALB instance.
EIPs support BGP (Multi-ISP) lines and BGP (Multi-ISP) Pro lines. The following table describes 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. ||BGP (Multi-ISP) Pro lines optimize data transmission to the Chinese mainland and improve connection quality for international services. Compared with BGP (Multi-ISP) lines, when BGP (Multi-ISP) Pro lines provide services to users in the Chinese mainland (excluding data centers), cross-border connections are established by using Chinese mainland ISP services. This reduces network latency.|
|Region||All regions||China (Hong Kong), Singapore, Malaysia (Kuala Lumpur), Philippines (Manila), Indonesia (Jakarta), and Thailand (Bangkok)|
Note BGP (Multi-ISP) Pro EIPs in the Singapore, Malaysia (Kuala Lumpur), Philippines (Manila), Indonesia (Jakarta), and Thailand (Bangkok) region support only the pay-as-you-go billing method.
Differences between an EIP and the static public IP address of an ECS instance
The following table describes the differences between an EIP and the static public IP address of an ECS instance.
|Item||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 anytime||Supported||Not supported|
|Displayed in the ENI information of the associated ECS instance||Cut-through mode: Displayed|
Classic network: Displayed
VPC: Not displayed
- Allow you to 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.
- Allow you to associate with resources anytime
You can associate an EIP with a cloud resource as needed. You can also disassociate and release an EIP anytime to prevent unexpected charges.
- Allow you to adjust the maximum bandwidth on demand
You can modify the maximum bandwidth of an EIP based on your business requirements. The modification immediately takes effect.
- Support flexible billing and lower costs
Multiple billing methods are supported, including subscription, pay-by-bandwidth, and pay-by-data-transfer. You can associate an EIP with an EIP bandwidth plan to reduce bandwidth costs.
Work with EIPs
- Use the EIP console. For more information, see Quick start.
- Call EIP API operations. All operations supported in the EIP console can be performed by calling EIP API operations. For more information, see List of operations by function.
Services that work with EIP
Resources that can be associated with EIPs
EIPs can be associated with different cloud resources to meet different requirements:
- ECS: a cloud computing service that provides elastic and efficient computing capability. For more information, see What is ECS?.
- CLB: a load balancing service that distributes traffic to backend instances based on forwarding rules. For more information, see What is CLB?.
- ALB: a load balancing service that runs at the application layer and supports protocols such as HTTP, HTTPS, and Quick UDP Internet Connections (QUIC). For more information, see What is ALB?.
- NAT Gateway: an address translation service that supports SNAT and DNAT. For more information, see What is NAT Gateway?.
- ENI: a virtual network interface controller (NIC) that can be associated with an ECS instance in a VPC. You can use ENIs to deploy high availability clusters and perform low-cost failover and fine-grained network management. For more information, see Overview.
- HAVIP: a private IP resource that you can independently create and release. You can use HAVIPs with software that supports high availability, such as Keepalived, to improve your service availability. For more information, see Overview of HAVIPs.
Other Internet connection services provided by Alibaba Cloud
You can also use the following services to reduce costs for Internet connections or improve Internet connection quality.
- EIP bandwidth plans: support bandwidth sharing and multiplexing within the same region. For more information, see What is an EIP bandwidth plan?.
- Anycast EIPs: can be anycast from access point locations around the world to improve Internet connection availability. For more information, see What is Anycast EIP? and Comparison between Anycast EIPs and EIPs.