What is EIP? - Elastic IP Address - Alibaba Cloud Documentation Center

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.

Features


Feature	Description	References
Apply for an EIP	Apply for a new EIP Restore a released EIP Apply for contiguous EIPs	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 ECS instance deployed in a VPC Associate an EIP with a CLB instance deployed in a VPC Associate an EIP with a NAT gateway Associate an EIP with an HAVIP Associate an EIP with a secondary ENI	Associate an EIP with an ECS instance Associate with a CLB instance Associate an EIP with a NAT gateway Associate an EIP with an HAVIP Associate an EIP with a secondary ENI
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

Note Application Load Balancer (ALB) instances can use EIPs to provide services over the Internet.

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.

Line types

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. Provides high-quality BGP lines across the globe. Uses BGP lines from different ISPs at the same time and automatically selects the optimal BGP line to ensure network stability. Supported ISPs are China Telecom, China Unicom, China Mobile, China Mobile Tietong, China Netcom, CERNET, NRTA, Dr.Peng Group, and Founder Broadband. You can use BGP (Multi-ISP) with EIP bandwidth plans to obtain bandwidth of 100 Gbit/s and higher.	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

Benefits

EIPs have the following benefits:

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.

Scenarios

You can use EIPs together with other cloud services to meet different requirements.

Work with EIPs

You can manage EIPs, create EIPs, and associate EIPs with resources by using the following methods:

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.