Global Accelerator listeners - Global Accelerator - Alibaba Cloud Documentation Center

After you create a standard GA instance, configure listeners for the standard GA instance. A listener checks connection requests and distributes traffic to endpoints based on the forwarding method defined by the listener's routing type.

Listener protocols

You can create up to 50 listeners for each GA instance. Listeners support the TCP, UDP, HTTP, and HTTPS protocols. You can select a listener protocol based on your application scenario.

Protocol	Description	Scenarios
TCP	A connection-oriented protocol that provides high reliability. A reliable connection must be established before data is sent or received. Supports session persistence based on source IP addresses. Source IP addresses are visible at the network layer. Data is transmitted at a slow rate.	Suitable for scenarios that require high reliability and data accuracy but can tolerate a low transmission speed, such as file transfers, email, and remote logons. Web applications that do not have special requirements.
UDP	A connectionless protocol with low reliability. A three-way handshake is not required before data is sent. It does not provide an error recovery or data retransmission mechanism. Data is transmitted at a high rate.	Suitable for scenarios that prioritize real-time performance and have lower reliability requirements, such as video chats and real-time financial market data pushes.
HTTP	A connection-oriented protocol that provides high reliability. A reliable connection must be established before data is sent or received. Data is transmitted at a high rate. Data is transmitted in plaintext.	Suitable for scenarios where you need to accelerate access to HTTP websites and improve the access speed for clients. Suitable for scenarios where you need to accelerate access to HTTP websites that use multiple domain names or paths.
HTTPS	A connection-oriented protocol that provides high reliability. A reliable connection must be established before data is sent or received. Ensures high data reliability using an SSL certificate. Note For more information about SSL certificates, see What is Digital Certificate Manager. Data is encrypted during transmission. You can configure the maximum HTTP protocol version to enable HTTP/3 access. This further improves the stability, security, and efficiency of data transmission.	Suitable for scenarios where you need to accelerate access to HTTPS websites and improve the speed and security of client access. Suitable for scenarios where you need to accelerate access to HTTPS websites that use multiple domain names or paths.

Listener routing types

Listeners support two routing types: smart routing and custom routing. You can select a routing type based on your application scenario.

Note

The custom routing listener feature is available for invitational preview. To use this feature, contact your account manager. After your request is approved, you can select the routing type for your listeners.

Smart routing listeners

Smart routing is the default routing type for a standard listener. GA automatically selects a nearby and healthy endpoint group based on latency factors, such as geographic location and network link conditions. GA then forwards client requests to the optimal endpoint.

This routing type is suitable for applications that require fine-grained control over global traffic. You can configure traffic weights for endpoint groups and endpoints to meet your requirements. Examples include blue-green deployments, A/B testing, multi-region deployments, phasing out or upgrading services by region, and multi-region disaster recovery. For more information about application scenarios and examples, see Traffic distribution principles and scenarios for multiple endpoint groups and Use GA to smoothly switch traffic across regions.

Smart routing listeners support the TCP, UDP, HTTP, and HTTPS protocols.

Custom routing listeners

GA generates a port mapping table based on the configured listener port range, the destination port range of the endpoint group, and the IP addresses of the endpoints (vSwitches). A custom routing listener uses this port mapping table to route client traffic to specific IP addresses and ports on a vSwitch.

This routing type is suitable for applications that require you to precisely map clients to backend services. It can assign multiple users to specific servers. Examples include multiplayer games, video conferencing, and virtual classrooms. For more information about how custom routing listeners work and for usage examples, see How custom routing listeners work.

Custom routing listeners support only the TCP and UDP protocols. You must specify the protocols when you configure the endpoint group. You can specify one or more protocols for each configured destination port range of an endpoint group. You can specify TCP, UDP, or both.

Note

A single GA instance cannot simultaneously support listeners of different routing types. The routing type cannot be changed after the listener is configured. For more information about the functional differences between the two routing types, see Comparison between smart routing and custom routing listeners.

Listener ports

A listener port receives requests and forwards them to endpoints.

Smart routing listener ports

Note

For smart routing listeners on the same GA instance:

TCP, HTTP, and HTTPS listeners must use different ports.
UDP listeners and HTTP/3 listeners must use different ports.

The following table describes the number of configurable ports and the limits for each listener protocol.

Listener protocol	Configurable listener port range	Listener port quota
TCP	1 to 65499	30. Separate multiple ports with commas (,). Example: `80,90,8080`. Use a hyphen (-) to specify a port range. For example, to specify ports 80, 81, 82, and 83, enter `80-83`.
UDP	1 to 65499	30. Separate multiple ports with commas (,). Example: `80,90,8080`. Use a hyphen (-) to specify a port range. For example, to specify ports 80, 81, 82, and 83, enter `80-83`.
HTTP	1 to 65499	1.
HTTPS	1 to 65499	1.

The following limits apply to TCP and UDP listeners based on the billing method of the GA instance:

Pay-as-you-go mode

You can configure multiple port ranges that contain consecutive ports for a single listener. The configurable port range is 1 to 65499. The port ranges cannot overlap.
The number of ports that you can add to a single listener depends on the gaplus_quota_port_per_listener quota. Each configured port or port range consumes one quota.
The total number of ports, including individual ports and port ranges, that you can add to all listeners on a single GA instance depends on the gaplus_quota_listener_per_accelerator quota. The total number of ports and port ranges that you add to all listeners on a single GA instance cannot exceed the gaplus_quota_listener_per_accelerator quota.
Note
The default value of the gaplus_quota_listener_per_accelerator quota is 50. To request a quota increase, contact your business manager.
For example, if you configure a TCP listener for a GA instance with the ports 1,3-350,400-800, this consumes three units of the gaplus_quota_port_per_listener quota.
You can add up to 27 more ports or port ranges to this TCP listener. If the number of ports and port ranges for this TCP listener reaches 30, you can add up to 20 ports or port ranges to other TCP or UDP listeners on the same GA instance.

Warning

After you configure the listener ports, modifying the ports or protocol may cause traffic interruptions. You must perform this operation with caution. We recommend that you perform these modifications during off-peak hours or after you switch traffic to another GA instance.

Subscription mode

The number of ports that you can add to a single listener depends on the gaplus_quota_port_per_listener quota. Each port consumes one quota.
For example, if you configure a TCP listener for a GA instance on ports 1,3-5, four gaplus_quota_port_per_listener quotas are consumed. You can add up to 26 more ports to this TCP listener.
By default, you can configure a port range of more than 300 consecutive ports for a single listener. A listener with more than 300 consecutive ports is called a massive-port listener. The following limits apply to massive-port listeners:
- If you cannot configure a port range of more than 300 consecutive ports for a TCP or UDP listener, the GA instance version may not support this feature. To use this feature, contact your business manager to upgrade the instance.
- You must configure more than 300 ports. You can configure up to 65,499 ports.
- Each subscription GA instance supports only one massive-port listener.
- A massive-port listener consumes one unit of the gaplus_quota_port_per_listener quota.
For example, you need to configure the following listeners for a GA instance: TCP 1-400, TCP 443, UDP 200-210, and UDP 230-240. In this case, TCP 1-400 is a massive-port listener.

Warning

Custom routing listener ports

The following limits apply to the ports of custom routing listeners:

The configurable port range is 1 to 65499. Ports 25, 250, 4789, and 4790 are reserved by the system. The system automatically ignores the reserved ports when it generates a port mapping table. Pay-as-you-go GA instances do not support port 6081.
The listener port range that you configure determines the number of port and IP address combinations in the associated endpoint group and its endpoints. The number of listener ports must meet the following requirement: Number of listener ports (excluding system-reserved ports) ≥ Total number of ports in the endpoint group × Total number of IP addresses of all vSwitches in the endpoint group. We recommend that you configure a large port range for the listener.
For example, if the destination port range of your endpoint group is 81-85, which includes five ports, and the total number of IP addresses for all vSwitch endpoints is 16, the listener port range must contain at least 80 ports (5 × 16 = 80). You can set the listener port range to 101-180, but not to 101-179. If the listener port range is smaller than required, the listener cannot be created.
After you configure the listener ports, you cannot remove ports that have existing mappings when you modify the port range.
For example, if the original listener port range is 100-10000 and a mapping exists between port 199 and the destination port 80 of the endpoint in the port mapping table, you can expand the listener port range to 20-10000. However, you cannot narrow the listener port range to 200-10000.
The listener ports of different listeners on the same GA instance cannot be the same.