Application Load Balancer (ALB) is a Layer 7 load balancing service that handles HTTP, HTTPS, and QUIC traffic with elastic, large-scale processing capabilities. ALB features advanced routing, integrates with cloud-native services, and serves as the official Alibaba Cloud Ingress gateway.
Why use Application Load Balancer (ALB)
Application Load Balancer (ALB) provides application-layer processing and advanced routing capabilities for HTTP, HTTPS, and QUIC applications. As the official Alibaba Cloud Ingress gateway, it is a core component of cloud-native architectures. For more information about how to use ALB Ingress, see Manage ALB Ingresses and ALB Ingress features.
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High elasticity at the application layer: ALB operates at the application layer, providing domain names and VIPs to handle large-scale requests. It distributes traffic to increase application capacity and eliminates single points of failure. You can customize availability zone combinations and scale elastically across them to prevent resource bottlenecks.
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Advanced protocol support: ALB supports HTTP, HTTPS, and QUIC protocols for massive traffic volumes. For mobile internet applications such as real-time audio/video, live streaming, and gaming, ALB delivers faster access and more reliable transmission. ALB also supports gRPC for API communication between microservices.
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Advanced content-based routing: ALB identifies and forwards service traffic to different backend servers based on conditions such as path, HTTP header, query string, request method, cookie, and source IP. ALB also supports redirection, rewrite, and custom HTTPS headers.
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Security and reliability: ALB provides built-in DDoS protection and integrates with Web Application Firewall (WAF). It offers end-to-end HTTPS encryption with predefined and custom security policies, and supports TLS 1.3. For encryption-sensitive services, ALB meets next-generation zero-trust security requirements.
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Built for cloud-native: As the cloud-native paradigm matures, new services are increasingly deployed in a cloud-native environment, while existing ones are re-architected to be cloud-native. ALB is tightly integrated with Container Service for Kubernetes (ACK), Serverless App Engine (SAE), Function Compute, and open source K8s. It is the official cloud-native Ingress gateway of Alibaba Cloud.
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SSE streaming: ALB supports Server-Sent Events (SSE) streaming. In large language model (LLM) applications, SSE returns inference results in real time for a better user experience.
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Flexible billing: ALB provides public network access through Elastic IP Addresses (EIPs) and Bandwidth Packages for flexible billing. ALB uses a pricing model based on Load Balancer Capacity Units (LCUs) that adapts to elastic traffic peaks.
Instance performance metrics
Starting from 00:00:00, February 25, 2025 (UTC+8), newly created instances will use the upgraded ALB version by default. Existing ALB instances are not affected, except for instances created through self-service applications. For more information, see Notice on the Upgrade of Application Load Balancer (ALB) Instances.
After upgrade
An ALB instance allocates three IP addresses from each specified vSwitch: a VIP (Virtual IP address) for client services, and two local IP addresses for communicating with backend servers and performing health checks.
To ensure all elastic capabilities of your ALB instance are available, we recommend that you reserve at least eight IP addresses in each vSwitch where the instance is deployed.
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VIP performance metrics |
Maximum auto-scaling performance |
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Maximum requests per second (QPS) |
500,000 |
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Maximum new connections per second (CPS) |
200,000 |
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Maximum concurrent connections |
5,000,000 |
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Maximum private network bandwidth |
25 Gbps |
The default public bandwidth of an ALB instance deployed in two availability zones is 400 Mbit/s. The actual public bandwidth is the sum of the bandwidth of all EIPs associated with the ALB instance.
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Within a single region, the total peak bandwidth of all pay-by-data-transfer EIPs under a single Alibaba Cloud account cannot exceed 5 Gbit/s. For more information, see the bandwidth limit section in Pay-as-you-go.
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If you require more bandwidth, purchase a Bandwidth Package. For more information, see Create and manage Bandwidth Packages.
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ALB supports multi-zone deployment. If the current region offers two or more availability zones, select at least two availability zones to ensure high availability for your services. ALB does not charge extra fees for using multiple availability zones.
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We recommend that you use your own domain name and create a CNAME record to map it to the domain name of the ALB instance to serve your clients. This configuration provides a service level agreement (SLA) of up to 99.995%.
The performance metrics in the preceding table represent the maximum auto-scaling performance of an ALB instance and are independent of the instance's feature edition.
Before upgrade
ALB provides two IP modes: Dynamic IP and Static IP. The performance of an ALB instance differs between the dynamic IP and static IP modes.
ALB instance performance metrics depend only on the ALB's IP mode, not the feature version.
Performance of a single ALB instance (using a two-zone deployment as an example)
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IP mode |
Maximum requests per second (QPS) |
Maximum new connections per second (CPS) |
Maximum concurrent connections |
Maximum private network bandwidth |
Default public bandwidth |
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Dynamic IP |
1,000,000 |
1,000,000 |
10,000,000 |
100 Gbit/s |
400 Mbit/s. The actual public bandwidth is the sum of the bandwidth of all EIPs associated with the ALB instance.
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Static IP |
100,000 |
100,000 |
1,000,000 |
10 Gbit/s |
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In regions that support multiple availability zones, the initial limits for QPS, CPS, and concurrent connections of an ALB instance are 100,000, 100,000, and 1,000,000, respectively. These limits do not increase with the number of availability zones. The maximum QPS, CPS, and concurrent connections of an ALB instance in Static IP mode are 100,000, 100,000, and 1,000,000, respectively. An ALB instance in Dynamic IP mode automatically scales out based on the auto-scaling SLA. The maximum QPS, CPS, and concurrent connections can reach 1,000,000, 1,000,000, and 10,000,000, respectively.
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We recommend that you use your own domain name and create a CNAME record to map it to the domain name of the ALB instance to serve your clients. This configuration provides an SLA of up to 99.995%.
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ALB supports multi-zone deployment. If the current region offers two or more availability zones, select at least two availability zones to ensure high availability for your services. ALB does not charge extra fees for using multiple availability zones.
ALB components
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Component |
Description |
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Instance |
An ALB instance provides Layer 7 load balancing. It distributes traffic to backend servers, increasing your application's service throughput. A single instance can handle up to 1,000,000 QPS. |
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Listener |
A listener monitors connection requests for an ALB instance. Configure each listener with a protocol and port to specify the traffic the ALB instance processes, such as HTTP traffic on port 80. An ALB instance requires at least one listener and supports up to 50 listeners per ALB instance for different types of service traffic. |
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Forwarding rule |
A forwarding rule determines how an ALB instance routes requests to server groups. Beyond traditional domain-name and path-based routing, ALB can forward requests based on HTTP headers, cookies, and request methods for flexible traffic scheduling. |
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Server group |
A server group is a set of backend servers that process requests distributed by ALB. In ALB, server groups are independent of ALB instances, so you can attach the same group to multiple ALB instances. Each server group supports up to 1,000 backend servers. ALB server groups support various backend types, including ECS, ECI, and ENI. |
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Health check |
ALB uses health checks to monitor backend server availability. ALB detects unhealthy servers and stops distributing traffic to them. ALB supports configurable health checks by protocol, port, and thresholds. ALB also provides health check templates that you can apply across server groups. |
ALB types
Alibaba Cloud provides internet-facing and internal-facing ALB instances. You can configure either a public-facing or private ALB instance based on your business needs. Your selection determines whether EIPs and Bandwidth Packages are used.
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Component |
Description |
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VIP (Virtual IP address) |
The virtual IP address that an ALB instance uses to distribute traffic. Each VIP is a private IP address within a Virtual Private Cloud (VPC). |
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EIP |
EIPs are required only for internet-facing ALB instances, not for internal-facing ALB instances. An EIP enables an ALB instance to provide services over the internet. An internet-facing ALB instance can have multiple EIPs and must have at least two in different availability zones for ALB high availability. |
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Bandwidth Package |
A Bandwidth Package enables bandwidth sharing and reuse across a region. Add EIPs in the same region to a Bandwidth Package to share bandwidth and reduce public bandwidth costs. |
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Domain name |
A resolvable domain name that maps to the corresponding VIP. You can also map a custom domain name that you own to the domain name of the ALB instance by using a CNAME record. For more information, see Configure a CNAME record for an ALB instance. Note
Starting from 00:00:00, November 15, 2024 (UTC+8), new domain names are used by default for newly created ALB instances. You can no longer use the default Alibaba Cloud domain names to access ALB instances. ALB instances created before 00:00:00, November 15, 2024 (UTC+8) are not affected. For more information, see Notice on the Upgrade of Load Balancer Domain Names. |
Activate Application Load Balancer (ALB)
Click Create Application Load Balancer to go to the ALB product purchase page.
Deploy and maintain ALB
After you register an Alibaba Cloud account, you can deploy and maintain ALB in the following ways:
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Application Load Balancer (ALB) console: A web-based UI for interactive operations. You can use the console to create, manage, or release an ALB instance. For more information, see Create and manage an ALB instance.
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Alibaba Cloud SDKs: Provides SDKs for various programming languages, such as Java, Go, and Python.
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OpenAPI Developer Portal: Offers quick API searches, online API calls, and dynamic SDK example code generation.
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Terraform: An open-source tool that lets you use versioned configuration files to provision and manage computing resources on Alibaba Cloud and other platforms that support Terraform.