What is an Elastic IP Address (EIP)-Elastic IP Address(EIP)-阿里云帮助中心

Use cases

Provide internet access for ECS instances

Associate an EIP with an ECS instance or ENI to provide internet access.

Create a unified internet gateway

Associate an EIP with an Internet NAT Gateway or SLB instance to create a unified gateway for internet traffic.

Build a high-availability, public-facing service

Associate an EIP with a High-availability Virtual IP (HaVip) to expose a highly available service to the internet.

Optimize international access for users in the Chinese mainland

A BGP (Multi-ISP) Pro EIP uses dedicated carrier lines to reduce latency for users in the Chinese mainland.

Benefits

Flexible management: Associate or disassociate an EIP at any time to handle service changes and failover.
On-demand scaling: Adjust bandwidth caps on demand. Changes take effect immediately.
Cost optimization: EIPs support pay-by-bandwidth and pay-by-data-transfer billing. Add a pay-as-you-go EIP to an Internet Shared Bandwidth instance to reuse bandwidth and reduce costs.
Security and reliability: EIPs include basic DDoS protection by default. For stronger protection, use an Anti-DDoS (Enhanced) EIP.

EIP vs. static public IP

VPC resources use public IPv4 addresses for internet access. These addresses are categorized as static public IPs and EIPs.

A static public IP is assigned only at resource creation (such as ECS or Classic Load Balancer (CLB) instances) and cannot be disassociated or reassigned—it is released when the resource is deleted. An EIP is an independent resource you can dynamically associate or disassociate, providing greater management flexibility. We recommend EIPs.

Public-facing Application Load Balancer (ALB), Network Load Balancer (NLB), and Internet NAT Gateways use EIPs for internet access.

You can convert static public IPs of ECS and CLB instances to EIPs.

EIP selection

Billing method

Billing method	Pay-as-you-go		Subscription
Billing method	Pay-as-you-go (pay-by-data-transfer)	Pay-as-you-go (pay-by-bandwidth)	Subscription (pay-by-bandwidth)
Billable items	Internet data transfer fee (data transfer fee) Rules for default settlement and billing using CDT. You are billed for an EIP's total outbound traffic, which flows from Alibaba Cloud data centers to the Internet. Inbound traffic is not billed. EIP configuration fee (public IP retention fee) Scenarios where no EIP configuration fee (public IP retention fee) is charged.	Internet data transfer fee (bandwidth fee) EIP configuration fee (public IP retention fee) Scenarios where the EIP configuration fee (public IP retention fee) does not apply.	Internet data transfer fee (bandwidth fee)
Billing cycle and bill generation time	The billing cycle is 1 hour. If usage in a billing cycle is less than 1 hour, you are charged for 1 hour. A bill is generated within 1 hour after the current billing cycle ends. The exact bill generation time depends on the system.	The billing cycle is 1 day. Billing is daily. A bill is generated in the early hours of the next day. The exact bill generation time depends on the system.	The billing cycle is the purchase period specified in your order (in UTC+8), starting from the resource activation or renewal time (accurate to the second) until 24:00:00 on the expiration date. Bill generation time: A bill is usually generated on the first day of the following calendar month. The exact bill generation time depends on the system.
Scenarios	Scenarios with large traffic fluctuations, such as gaming and video applications. Scenarios with temporary or bursty resource usage. If you cannot estimate your traffic usage, choose pay-by-data-transfer.	Scenarios with stable traffic peaks. Scenarios with temporary or bursty resource usage.	Scenarios where the resource usage period can be estimated. Scenarios with stable traffic peaks. Scenarios requiring long-term resource use. Subscription is more cost-effective than pay-as-you-go with pay-by-bandwidth.
Cost optimization	Upgrade to CDT: CDT offers free data transfer quotas and tiered pricing. Associate the EIP with Internet Shared Bandwidth. Purchase a Data Transfer Plan to offset data transfer costs.	Associate the EIP with Internet Shared Bandwidth.	-

Line type

Important

You can select a line type only when you create an EIP. You cannot change it later.

Line type	BGP (Multi-ISP)	BGP (Multi-ISP) Pro
Description	Connects to multiple ISP lines and automatically selects the optimal path for fast, stable access. Available in all Alibaba Cloud regions.	A premium line for traffic from outside the Chinese mainland to end users within the Chinese mainland (excluding data centers). Uses dedicated ISP connections to reduce latency and improve cross-border service quality.
Use cases	Default choice for most internet-facing services. Provides network stability and broad coverage.	Optimized for inbound traffic to the Chinese mainland. Significantly reduces cross-border network latency.
Limitations	Services can be deployed in any Alibaba Cloud region. End users can access the service from any location via the internet.	Services can be deployed only in specific regions outside the Chinese mainland. The available regions depend on the billing method. Supported regions for BGP (Multi-ISP) Pro EIPs Pay-as-you-go: China (Hong Kong), Japan (Tokyo), Singapore, Malaysia (Kuala Lumpur), Philippines (Manila), Indonesia (Jakarta), and Thailand (Bangkok). Subscription: China (Hong Kong). End users access the service from within the Chinese mainland via the internet.
Cost	Low	Medium

Security protection