Enable public bandwidth for an ECS instance-Elastic Compute Service(ECS)-阿里云帮助中心

Choose a method to enable Internet access for an ECS instance based on your requirements.

Enable IPv4 public bandwidth

Method	Applicable scenario	Benefit	References
Assign a static public IP address to the ECS instance	The ECS instance needs a static public IP address (auto-assigned) for long-term Internet access, such as continuous services.	Assignable at instance creation or to an existing instance. Dedicated to the instance and released with it. Simple to set up.	Assign a static public IP address to an ECS instance when the instance is created. ECS console: Custom launch ECS instances API operation: RunInstances Assign a static public IP address to an existing ECS instance. ECS console: Modify fixed public bandwidthModify public bandwidth for subscription instances API operation: ModifyInstanceNetworkSpec
Associate an Elastic IP Address (EIP) with the ECS instance	Internet access or network configuration changes are temporary or dynamic. Examples: Frequent backend server replacements or redeployments, such as temporary test, development, or demo environments. Fast failover: disassociate the EIP from a failed instance and associate it with a standby instance to minimize service interruption. Scale a service across multiple instances while keeping the same IP address. Multiple services on one instance each need an independent public IP address.	An EIP is a separately purchasable public IP address. You can disassociate an EIP from an instance and associate the EIP with another instance. More flexible and easier to manage than other methods.	Associate or disassociate an EIP
Associate an Anycast EIP with the ECS instance	Enhances service availability over the Internet outside the Chinese mainland. Traffic routes through carrier lines and the Alibaba Cloud global transmission network.	Multiple regions share the same Anycast EIP. Traffic routes to the nearest Alibaba Cloud access point to reduce latency. An Anycast EIP is globally unique and can be announced from all access points in an access area, not limited by region.	What is Anycast EIP?
Use a NAT gateway to translate network addresses	Multiple ECS instances need shared Internet access or public bandwidth, or have special access requirements. Examples: Instances access external networks without being exposed to the Internet. Services only need outbound connections, such as backend services and databases. Multiple instances share a public IP address due to limited IP resources. All instances in a private subnet share the same Internet egress.	Provides a centralized, controllable Internet egress. Saves public IP resources — no per-instance public IP assignment needed. Simplifies network architecture with centralized outbound access policy management. Instances are not directly exposed to the Internet, improving security.	Use the SNAT feature of an Internet NAT gateway to access the Internet Configure DNAT on an Internet NAT gateway for an ECS instance
Distribute Internet traffic with Server Load Balancer (SLB)	Large-scale, high-concurrency Internet applications, such as Double 11 promotions and IoT applications. Enterprise applications requiring high availability, automatic failover, and cross-zone load balancing. Web applications that need to handle traffic spikes automatically.	Associate multiple backend servers with an SLB instance across zones to distribute IPv4 and IPv6 traffic, eliminate single points of failure, and improve availability. SLB product family	Getting Started

Enable IPv6 public bandwidth

Method

Applicable scenario

Benefit

References

Assign an IPv6 address for which public bandwidth is enabled to the ECS instance

Applications or services that support IPv6.

Services that communicate with IPv6 terminals.
Large-scale IoT and cloud services requiring massive device connections.

IPv6 provides a larger address space and supports direct access to the IPv6 Internet.

Manage IPv6 addresses

Distribute Internet traffic with SLB

Large-scale, high-concurrency Internet applications, such as Double 11 promotions and IoT applications.

Enterprise applications requiring high availability, automatic failover, and cross-zone load balancing.
Web applications that need to handle traffic spikes automatically.

Associate multiple backend servers with an SLB instance across zones to distribute IPv4 and IPv6 traffic, eliminate single points of failure, and improve availability. SLB product family

Getting Started

References

To modify bandwidth configurations or change billing methods for static public IP addresses and EIPs, see Modify bandwidth configurations.
Billing details: Public bandwidth billing, Billing overview of EIPs, Billing rules of Anycast EIPs, Billing overview of NAT Gateway, Billing rules of IPv6 gateways, and Server Load Balancer billing.
To host multiple applications with independent public IP addresses on one instance, associate multiple EIPs through secondary elastic network interfaces (ENIs). See Bind Multiple EIPs to ECS via ENIs.