Limits on Classic Load Balancer - Server Load Balancer - Alibaba Cloud Documentation Center

This topic describes the limits on Classic Load Balancer (CLB), including resource quotas and bandwidth limits. This topic also describes how to request a quota increase.

Resource quotas

Limits on CLB instances

Item	Default value	Adjustable
Maximum number of CLB instances that can be created by each Alibaba Cloud account	30	You can request a quota increase by using one of the following methods: Go to the Quota Management page in the CLB console, find the quota slb_quota_instances_num, and then click Apply in the Actions column. For more information, see Manage quotas. Log on to the Quota Center console and request a quota increase. For more information, see Manage CLB quotas.
Maximum number of times that a server can be added as a CLB backend server	50	You can request a quota increase by using one of the following methods: Go to the Quota Management page in the CLB console, find the quota slb_quota_backendserver_attached_num, and then click Apply in the Actions column. For more information, see Manage quotas. Log on to the Quota Center console and request a quota increase. For more information, see Manage CLB quotas.
Maximum number of backend servers that can be added to a CLB instance	200	You can request a quota increase by using one of the following methods: Go to the Quota Management page in the CLB console, find the quota slb_quota_backendservers_num, and then click Apply in the Actions column. For more information, see Manage quotas. Log on to the Quota Center console and request a quota increase. For more information, see Manage CLB quotas.
Maximum number of listeners that can be added to a CLB instance	50	You can request a quota increase by using one of the following methods: Go to the Quota Management page in the CLB console, find the quota slb_quota_listeners_num, and then click Apply in the Actions column. For more information, see Manage quotas. Log on to the Quota Center console and request a quota increase. For more information, see Manage CLB quotas.
Maximum number of domain name-based and URL-based forwarding rules that can be added to an HTTP or HTTPS listener	40	No
Maximum number of additional domain names that can be created for an HTTPS listener The default quota is 3. The highest quota that you can apply for is 10.	3	You can request a quota increase by using one of the following methods: Go to the Quota Management page in the CLB console, find the quota slb_quota_domain_extensions_num, and then click Apply in the Actions column. For more information, see Manage quotas. Log on to the Quota Center console and request a quota increase. For more information, see Manage CLB quotas.
Range of frontend or backend ports that can be specified for a CLB listener (public cloud)	1~65535	No

Limits on certificates

Item

Default value

Adjustable

Maximum number of server certificates that can be uploaded in a region

100

You can request a quota increase by using one of the following methods:

Go to the Quota Management page in the CLB console, find the quota slb_quota_certs_num, and then click Apply in the Actions column. For more information, see Manage quotas.
Log on to the Quota Center console and request a quota increase. For more information, see Manage CLB quotas.

Maximum number of client certificate authority (CA) certificates that can be uploaded in a region

100

You can request a quota increase by using one of the following methods:

Go to the Quota Management page in the CLB console, find the quota slb_quota_ca_certs_num, and then click Apply in the Actions column. For more information, see Manage quotas.
Log on to the Quota Center console and request a quota increase. For more information, see Manage CLB quotas.

Limits on ACLs

Item	Default value	Adjustable
Maximum number of access control lists (ACLs) that can be configured by an Alibaba Cloud account	200	No
Maximum number of entries that can be added to an ACL	300	You can request a quota increase by using one of the following methods: Go to the Quota Management page in the CLB console, find the quota slb_quota_acl_entries_num, and then click Apply in the Actions column. For more information, see Manage quotas. Log on to the Quota Center console and request a quota increase. For more information, see Manage CLB quotas.
Maximum number of IP addresses or CIDR blocks that can be added to an ACL in each API call	50	No
Maximum number of times that each ACL can be associated with different listeners	50	You can request a quota increase by using one of the following methods: Go to the Quota Management page in the CLB console, find the quota slb_quota_acl_attached_num, and then click Apply in the Actions column. For more information, see Manage quotas. Log on to the Quota Center console and request a quota increase. For more information, see Manage CLB quotas.
Public key algorithms supported by CLB	RSA 1024 RSA 2048 RSA 4096 ECDSA P-256 ECDSA P-384 ECDSA P-521	No

Bandwidth limits

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

Pay-by-data-transfer CLB instance

Pay-by-bandwidth CLB instance

The maximum bandwidth of a pay-by-data-transfer Internet-facing CLB instance varies based on the region. You can view the maximum bandwidth of a pay-by-data-transfer CLB instance on the instance details page in the CLB console.

The maximum bandwidth is 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 the maximum bandwidth value.

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

The maximum bandwidth is guaranteed even if resource contention occurs. Rules for 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 maximum bandwidth of all pay-by-data-transfer 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 maximum bandwidth of all pay-by-bandwidth Internet-facing CLB instances in a region cannot exceed 50 Gbit/s. To request a quota increase, contact your account manager.

To view the maximum bandwidth of your CLB instance, log on to the CLB console and go to the Instances page. Then, click the ID of the CLB instance that you want to view. On the Instance Details tab, you can view the maximum bandwidth of the CLB instance.
In some scenarios, the bandwidth may not reach the maximum value. For more information, see Why do connections fail to reach the maximum bandwidth in specific scenarios? and Why does a CLB instance fail to reach the maximum QPS in specific scenarios?