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    ENS:SetLoadBalancerUDPListenerAttribute

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    ENS:SetLoadBalancerUDPListenerAttribute

    Last Updated:May 07, 2026

    Call SetLoadBalancerUDPListenerAttribute to modify a UDP listener.

    Operation description

    • API call rate limit: 100 requests/second.

    • Per-user rate limit: 10 requests/second.

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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 load balancer instance.

    lb-5pzipr2fszqtl2xf64uy5****
    ListenerPort

    integer

    Yes

    The listener port to modify. Valid values: 1 to 65535.

    80
    Description

    string

    No

    The name of the listener. The name must be 1 to 80 characters long.

    Note

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

    example
    Scheduler

    string

    No

    The scheduling algorithm. Valid values:

    • wrr: Weighted Round Robin. Backend servers with higher weights receive a larger proportion of requests.

    • wlc: Weighted Least Connections. Requests are distributed based on both the weights and the number of active connections of backend servers. If servers have the same weight, the server with the fewest active connections receives more requests.

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

    • sch: Source IP Hash. A consistent hash based on the source IP address. Requests from the same source IP address are routed to the same backend server.

    • tch: 4-Tuple Hash. A consistent hash based on the 4-tuple (source IP, destination IP, source port, and destination port). Flows with the same 4-tuple are routed to the same backend server.

    • qch: QUIC Connection ID Hash. A consistent hash based on the QUIC Connection ID. Requests with the same QUIC Connection ID are routed to the same backend server.

    • iqch: iQUIC CID Hash. A consistent hash based on three specific bytes (from the second to the fourth byte) of the iQUIC CID. Requests with identical values in these three bytes are routed to the same backend server.

    wrr
    HealthyThreshold

    integer

    No

    The number of consecutive successful health checks required to mark an unhealthy backend server as healthy. Valid values: 2 to 10.

    4
    UnhealthyThreshold

    integer

    No

    The number of consecutive failed health checks required to mark a healthy backend server as unhealthy. Valid values: 2 to 10.

    4
    HealthCheckConnectTimeout

    integer

    No

    The timeout for a health check response. If a backend ENS instance does not respond within this timeout period, the health check fails.

    • Default value: 5

    • Valid values: 1 to 300

    • Unit: seconds

    Note

    If the value of HealthCheckConnectTimeout is less than the value of HealthCheckInterval, the system ignores HealthCheckConnectTimeout and uses the value of HealthCheckInterval as the timeout period.

    100
    HealthCheckInterval

    integer

    No

    The interval, in seconds, between consecutive health checks. Valid values: 1 to 50.

    5
    HealthCheckConnectPort

    integer

    No

    The port used for health checks. Valid values: 1 to 65535. Defaults to the backend server port (BackendServerPort) if not specified.

    8080
    HealthCheckReq

    string

    No

    The request string for a UDP listener health check. The string can contain only letters and digits and must be at most 64 characters long.

    hello
    HealthCheckExp

    string

    No

    The expected response string for a UDP listener health check. The string can contain only letters and digits and must be at most 64 characters long.

    ok
    EipTransmit

    string

    No

    Specifies whether to enable EIP passthrough. Valid values:

    • on: Enables EIP passthrough.

    • off (default): Disables EIP passthrough.

    on
    EstablishedTimeout

    integer

    No

    The timeout for established connections, in seconds. The value must be an integer from 10 to 900. The default value is 900.

    500

    Response elements

    Element

    Type

    Description

    Example

    object

    Response schema

    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.