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ENS:SetLoadBalancerUDPListenerAttribute

Last Updated:Mar 27, 2026

Modifies a UDP listener.

Operation description

  • Rate limit: 100 requests per second.

  • up to 10 times per second per account.

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RAM authorization

The table below describes the authorization required to call this API. You can define it in a Resource Access Management (RAM) policy. The table's columns are detailed below:

  • Action: The actions can be used in the Action element of RAM permission policy statements to grant permissions to perform the operation.

  • API: The API that you can call to perform the action.

  • Access level: The predefined level of access granted for each API. Valid values: create, list, get, update, and delete.

  • Resource type: The type of the resource that supports authorization to perform the action. It indicates if the action supports resource-level permission. The specified resource must be compatible with the action. Otherwise, the policy will be ineffective.

    • For APIs with resource-level permissions, required resource types are marked with an asterisk (*). Specify the corresponding Alibaba Cloud Resource Name (ARN) in the Resource element of the policy.

    • For APIs without resource-level permissions, it is shown as All Resources. Use an asterisk (*) in the Resource element of the policy.

  • Condition key: The condition keys defined by the service. The key allows for granular control, applying to either actions alone or actions associated with specific resources. In addition to service-specific condition keys, Alibaba Cloud provides a set of common condition keys applicable across all RAM-supported services.

  • Dependent action: The dependent actions required to run the action. To complete the action, the RAM user or the RAM role must have the permissions to perform all dependent actions.

Action

Access level

Resource type

Condition key

Dependent action

ens:SetLoadBalancerUDPListenerAttribute

update

*All Resource

*

None None

Request parameters

Parameter

Type

Required

Description

Example

LoadBalancerId

string

Yes

The ID of the Edge Load Balancer (ELB) instance.

lb-5pzipr2fszqtl2xf64uy5****

ListenerPort

integer

Yes

The listener port whose attributes are to be modified. Valid values: 1 to 65535.

80

Description

string

No

The name of the listener. The valuemust be 1 to 80 characters in length.

Note

The value cannot start with http:// or https://.

example

Scheduler

string

No

The scheduling algorithm. Valid values:

  • wrr: Backend servers with higher weights receive more requests than those with lower weights.

  • wlc: Requests are distributed based on the weights and number of connections to backend servers. If two backend servers have the same weight, the backend server that has fewer connections receives more requests.

  • rr: Requests are distributed to backend servers in sequence.

  • sch: consistent hashing based on source IP addresses. Requests from the same source IP address are distributed to the same backend server.

  • qch: consistent hashing based on QUIC connection IDs (CIDs). Requests that contain the same QUIC CID are distributed to the same backend server.

  • iqch: consistent hashing based on three specific bytes of iQUIC CIDs. Requests with the same second, third, and fourth bytes are distributed to the same backend server.

wrr

HealthyThreshold

integer

No

The number of consecutive successful health checks that must occur before an unhealthy and inaccessible backend server is declared healthy and accessible. Valid values: 2 to 10.

4

UnhealthyThreshold

integer

No

The number of consecutive failed health checks that must occur before a healthy and accessible backend server is declared unhealthy and inaccessible. Valid values: 2 to 10.

4

HealthCheckConnectTimeout

integer

No

The timeout period of a health check response. If the backend ENS does not respond within the specified time, the health check fails.

  • Default value: 5.

  • Valid values: 1 to 300.

  • Unit: seconds.

Note

If the value of the HealthCheckTimeout property is smaller than the value of the HealthCheckInterval property, the timeout period specified by the HealthCheckTimeout property becomes invalid and the value of the HealthCheckInterval property is used as the timeout period.

100

HealthCheckInterval

integer

No

The interval at which health checks are performed. Valid values: 1 to 50. Unit: seconds.

5

HealthCheckConnectPort

integer

No

The port that is used for health checks. Valid values: 1 to 65535. If you leave this parameter empty, the port specified for BackendServerPort is used for health checks.

8080

HealthCheckReq

string

No

The request string for UDP listener health checks. The string can be up to 64 characters in length and can contain only letters and digits.

hello

HealthCheckExp

string

No

The response string for UDP listener health checks. The string can be up to 64 characters in length and can contain only letters and digits.

ok

EipTransmit

string

No

Specifies whether to enable elastic IP address (EIP) pass-through. Valid values:

  • on

  • off (default)

on

EstablishedTimeout

integer

No

The timeout period of a connection. Valid values: 10 to 900. Default value: 900. Unit: seconds.

500

Response elements

Element

Type

Description

Example

object

Schema of Response

RequestId

string

The ID of the request.

06F00FBB-3D9E-4CCE-9D43-1A6946A75456

Examples

Success response

JSON format

{
  "RequestId": "06F00FBB-3D9E-4CCE-9D43-1A6946A75456"
}

Error codes

HTTP status code

Error code

Error message

Description

400 Invalid%s The specified parameter %s is invalid.
400 Missing%s You must specify the parameter %s.
400 IncorrectInstanceStatus The current status of the resource does not support this operation. The current operation is not supported. The disk is being reset.
400 ens.interface.error Failed to call API.
400 LoadBalancerNotFound The input parameter LoadBalancerId that is not found. The load balancing instance does not exist.
400 IncorrectListenerStatus The current status of the resource does not support this operation. The listener status is incorrect.
400 ListenerNotFound Listener is not found. Listener does not exist
400 NoPermission Permission denied.
400 InvalidParameter.%s The specified field %s invalid. Please check it again.

See Error Codes for a complete list.

Release notes

See Release Notes for a complete list.