This topic describes the regions that support Classic Load Balancer (CLB).
Regions and zones
Regions are geographical locations where Alibaba Cloud data centers are deployed. After you create a resource in a region, you cannot change the region to which the resource belongs. Each region has multiple isolated locations known as zones. Each zone has its own independent power supply and network.
Zones within the same region can communicate with each other over an internal network. Fault isolation can be enabled between zones. This way, if faults occur in a zone, other zones are not affected and continue to run as expected. Regions are independent of each other. Zones are isolated from each other. Connections between zones within the same region provide low network latency.
Classic Load Balancer (CLB) supports cross-zone deployment in most regions. You can deploy a CLB instance across multiple zones within the same region to improve disaster tolerance and ensure the reliability of your applications. When the primary zone is down, Classic Load Balancer (CLB) can fail over to the secondary zone within about 30 seconds. When the primary zone recovers, Classic Load Balancer (CLB) automatically switches back to the primary zone.
Before you deploy a Classic Load Balancer (CLB) instance across zones, take note of the following items:
- You can add Elastic Compute Service (ECS) instances that are deployed across primary and secondary zones to a Classic Load Balancer (CLB) instance. However, the ECS instances and the Classic Load Balancer (CLB) instance must belong to the same region. Classic Load Balancer (CLB) can distribute network traffic to ECS instances across zones.
- By default, if the primary zone of a Classic Load Balancer (CLB) instance is active, network traffic is not distributed to the secondary zone. You cannot manually configure the Classic Load Balancer (CLB) instance to switch network traffic to the secondary zone. The CLB instance switches network traffic to the secondary zone only when the primary zone is down. For example, when the primary zone is down due to power outages or fiber cuts, the secondary zone of the Classic Load Balancer (CLB) instance automatically takes over. An unhealthy ECS instance does not trigger a zone failover.
- ECS instances are independent of Classic Load Balancer (CLB). If a Classic Load Balancer (CLB) instance in the primary zone fails, the ECS instances in the primary zone may still provide services. As shown in the preceding figure, for example, when Zone A of the Classic Load Balancer (CLB) instance fails, the secondary zone of the Classic Load Balancer (CLB) instance takes over. Classic Load Balancer (CLB) can distribute network traffic across the ECS instances that are deployed in different zones. However, if the whole zone is down due to power outages or fiber cuts, all resources in this zone stop running, including the Classic Load Balancer (CLB) instance and the ECS instances.
Regions that support CLB
The regions in the following table are listed for reference only. For more information, visit the buy page.
Regions that support IPv4 CLB instances on the Alibaba Cloud public cloud
| Geographical area | Regions |
|---|---|
| China | China (Qingdao), China (Beijing), China (Zhangjiakou), China (Hohhot), China (Hangzhou), China (Shanghai), China (Shenzhen), China (Heyuan), China (Guangzhou), China (Chengdu), and China (Hong Kong) |
| Asia Pacific | Philippines (Manila), Japan (Tokyo), Singapore (Singapore), Australia (Sydney), Malaysia (Kuala Lumpur), Indonesia (Jakarta), India (Mumbai), South Korea (Seoul), and Thailand (Bangkok) |
| Europe & Americas | US (Silicon Valley), US (Virginia), Germany (Frankfurt), and UK (London) |
| Middle East | UAE (Dubai) |
Classic Load Balancer (CLB) instances in the Thailand (Bangkok) region support only Layer 4 load balancing.
Regions that support IPv6 CLB instances on the Alibaba Cloud public cloud
| Geographical area | Regions |
|---|---|
| China | China (Qingdao), China (Beijing), China (Zhangjiakou), China (Hohhot), China (Hangzhou), China (Shanghai), China (Shenzhen), China (Heyuan), China (Guangzhou), China (Chengdu), and China (Hong Kong) |
| Asia Pacific | Singapore (Singapore) |
| Europe & Americas | US (Virginia) and Germany (Frankfurt) |
References
- DescribeRegions: queries the most recent region list.
- DescribeZones: queries zones in a specified region.