Limits - Server Load Balancer - Alibaba Cloud Documentation Center

This topic describes the limits on Classic Load Balancer (CLB).

Basic settings

Item	Limits	Adjustable
Limits on CLB instances		You can navigate to the Quota Management page to request a quota increase. For more information, see Manage service quotas.
Maximum number of CLB instances that you can create within an Alibaba Cloud account	30
Maximum number of CLB instances that can be associated with an Elastic Compute Service (ECS) instance	50
Maximum number of backend servers that can be added to a CLB instance	200
Maximum number of listeners that can be configured for a CLB instance	50
Maximum number of domain name-based and URL-based forwarding rules that can be added to an HTTP or HTTPS listener	40
Maximum number of additional certificates that can be created for an HTTPS listener	3
Range of frontend or backend ports that can be specified for a CLB listener (Alibaba Cloud)	1–65535
Range of frontend or backend ports that can be specified for a CLB listener (Alibaba Finance Cloud)	80 443 2800–3300 5000–10000 13000–14000
Limits on certificates
Maximum number of server certificates that can be uploaded in a region	100
Maximum number of client CA certificates that can be uploaded in a region	100
Limits on network access control lists (ACLs)
Maximum number of network ACLs that can be created in a region	50
Maximum number of IP addresses that can be added to a network ACL	300
Maximum number of IP addresses that can be added to a network ACL by making an API call	50
Maximum number of listeners that can be associated with a network ACL	50
Public key algorithms supported by CLB	RSA 1024 RSA 2048 RSA 4096 ECDSA P-256 ECDSA P-384 ECDSA P-521	N/A

Bandwidth limits

The following table describes the maximum bandwidth of Internet-facing CLB instances that use different billing methods for data transmission over the Internet.

Pay-by-data-transfer CLB instance	Pay-by-bandwidth CLB instance
The maximum bandwidth of an Internet-facing CLB instance varies based on the region. You can view the maximum bandwidth on the instance details page in the CLB console. The maximum bandwidth is used for reference only. It indicates the upper limit of the bandwidth. In case of resource contention, the bandwidth allocated to each CLB instance may be lower than its maximum bandwidth value.	The maximum bandwidth that you can specify for an Internet-facing CLB instance varies based on the region. For more information, visit the buy page. The maximum bandwidth is guaranteed even when resource contention occurs. Rules on inbound and outbound bandwidth: Inbound bandwidth of a CLB instance: the maximum bandwidth that you specify when you purchase a CLB instance. Outbound bandwidth of a CLB instance: the maximum bandwidth that you specify when you purchase a CLB instance.
For each Alibaba Cloud account, the sum of the peak bandwidth of all Internet-facing CLB instances in a region cannot exceed 5 Gbit/s. If your business requires guaranteed bandwidth or larger bandwidth, you can purchase pay-by-bandwidth CLB instances.	For each Alibaba Cloud account, the sum of the peak bandwidth of all Internet-facing CLB instances in a region cannot exceed 50 Gbit/s. To request a quota increase, contact customer service.

Pay-by-data-transfer CLB instance

Pay-by-bandwidth CLB instance

The maximum bandwidth of an Internet-facing CLB instance varies based on the region. You can view the maximum bandwidth on the instance details page in the CLB console.

The maximum bandwidth is used for reference only. It indicates the upper limit of the bandwidth. In case of resource contention, the bandwidth allocated to each CLB instance may be lower than its maximum bandwidth value.

The maximum bandwidth that you can specify for an Internet-facing CLB instance varies based on the region. For more information, visit the buy page.

The maximum bandwidth is guaranteed even when resource contention occurs. Rules on inbound and outbound bandwidth:

Inbound bandwidth of a CLB instance: the maximum bandwidth that you specify when you purchase a CLB instance.
Outbound bandwidth of a CLB instance: the maximum bandwidth that you specify when you purchase a CLB instance.

For each Alibaba Cloud account, the sum of the peak bandwidth of all Internet-facing CLB instances in a region cannot exceed 5 Gbit/s. If your business requires guaranteed bandwidth or larger bandwidth, you can purchase pay-by-bandwidth CLB instances.

For each Alibaba Cloud account, the sum of the peak bandwidth of all Internet-facing CLB instances in a region cannot exceed 50 Gbit/s. To request a quota increase, contact customer service.