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    Server Load Balancer:Limits

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    Server Load Balancer:Limits

    Last Updated:Sep 11, 2023

    This topic describes the limits on Network Load Balancer (NLB), including resource quotas.

    Resource quotas

    Resource

    Default value

    Adjustable

    NLB instance

    Maximum number of NLB instances that each Alibaba Cloud account can have in a region

    60

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

    • Go to the Quota Management page of the Server Load Balancer (SLB) console, click the NLB tab, and then increase the quota nlb_quota_loadbalancers_num.

    • Log on to the Quota Center console and request a quota increase.

    For more information, see Adjust quotas.

    Maximum number of elastic container instances that can be specified as backend servers for each NLB instance

    1,600

    No

    Maximum number of Elastic Compute Service (ECS) instances, elastic network interfaces (ENIs), or IP addresses that can be specified as backend servers for each NLB instance

    400

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

    • Go to the Quota Management page of the SLB console, click the NLB tab, and then increase the quota nlb_quota_loadbalancer_noeci_servers_num.

    • Log on to the Quota Center console and request a quota increase.

    For more information, see Adjust quotas.

    Maximum number of listeners that can be added to each NLB instance

    50

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

    • Go to the Quota Management page of the SLB console, click the NLB tab, and then increase the quota nlb_quota_loadbalancer_listeners_num.

    • Log on to the Quota Center console and request a quota increase.

    For more information, see Adjust quotas.

    Maximum number of additional certificates that can be added to each NLB instance (excluding the default certificate)

    25

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

    • Go to the Quota Management page of the SLB console, click the NLB tab, and then increase the quota nlb_quota_loadbalancer_certificates_num.

    • Log on to the Quota Center console and request a quota increase.

    For more information, see Adjust quotas.

    Server group

    Maximum number of NLB server groups that each Alibaba Cloud account can have in a region

    3,000

    No

    Maximum number elastic container instances that can be added to each server group

    1,600

    No

    Maximum number of ECS instances, ENIs, or IP addresses that can be added to each server group

    400

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

    • Go to the Quota Management page of the SLB console, click the NLB tab, and then increase the quota nlb_quota_servergroup_noeci_servers_num.

    • Log on to the Quota Center console and request a quota increase.

    For more information, see Adjust quotas.

    Maximum number of times that a backend server (including a backend server of the IP type) can be added to a server group

    200

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

    • Go to the Quota Management page of the SLB console, click the NLB tab, and then increase the quota nlb_quota_server_added_num.

    • Log on to the Quota Center console and request a quota increase.

    For more information, see Adjust quotas.

    Maximum number of times that each NLB server group can be associated with a listener

    50

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

    • Go to the Quota Management page of the SLB console, click the NLB tab, and then increase the quota nlb_quota_servergroup_attached_num.

    • Log on to the Quota Center console and request a quota increase.

    For more information, see Adjust quotas.

    Security policy

    Maximum number of custom security policies that each Alibaba Cloud account can have in a region

    50

    No

    Security group

    Maximum number of security groups to which each NLB instance can be added

    4

    No

    Other limits

    • If the number of backend server groups drops to a low number, and a single client visits the domain name of the NLB instance whose backend servers have client IP address preservation enabled, or accesses the virtual IP addresses or elastic IP addresses (EIPs) of both the NLB instance and a Classic Load Balancer (CLB) instance that share the same backend servers, conflicts may arise in source IP addresses, source ports, destination IP addresses, destination ports, and transmission protocols.

    • The private virtual IP addresses to which the domain name of an NLB instance is resolved support probes. However, you need to enable ICMP when you configure Cloud Firewall or access control lists. Otherwise, the NLB domain name may fail to be resolved to the virtual IP addresses due to probe failures.

    • If a UDP listener is associated with a server group that uses ID hashing algorithms other than QUIC, such as round robin and weighted round robin, the backend servers must not use stateful UDP services, such as QUIC. If the backend servers need to use stateful UDP services, we recommend that the server groups use QUIC-based ID hashing.