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    Express Connect:DescribeExpressConnectRouterAssociation

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    Express Connect:DescribeExpressConnectRouterAssociation

    Last Updated:Aug 20, 2026

    Queries the virtual private clouds (VPCs) and transit routers (TRs) associated with an Express Connect Router (ECR).

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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

    expressconnectrouter:DescribeExpressConnectRouterAssociation

    list

    *ExpressConnectRouter

    acs:expressconnectrouter::{#accountId}:expressconnectrouter/{#EcrId}

    		 None None

    Request parameters

    Parameter

    Type

    Required

    Description

    Example
    EcrId

    string

    Yes

    The Express Connect Router (ECR) instance ID.

    Note

    You can create an ECR instance and obtain the EcrId by calling the CreateExpressConnectRouter API operation.

    ecr-mezk2idmsd0vx2****
    AssociationId

    string

    No

    The associate ID between the Express Connect Router (ECR) and a VPC or TR.

    ecr-assoc-9p2qxx5phpca2m****
    AssociationRegionId

    string

    No

    The region to which the VPC or TR belongs.

    cn-hangzhou
    AssociationNodeType

    string

    No

    The type of the associated resource. Valid values:

    • VPC: virtual private cloud.

    • TR: transit router.

    VPC
    VpcId

    string

    No

    The ID of the VPC-connected instance.

    vpc-bp1h37fchc6jmfyln****
    TransitRouterId

    string

    No

    The ID of the transit router instance.

    tr-2ze4i71c6be454e2l****
    CenId

    string

    No

    The ID of the Cloud Enterprise Network (CEN) instance.

    cen-of3o1the3i4gwb****
    NextToken

    string

    No

    The pagination token. Valid values:

    • You do not need to specify this parameter for the first request or if no next query exists.

    • If a next query exists, set the value to the NextToken value returned in the previous API call.

    AAAAAYws9fJ0Ur4MGm/5OkDoW/Zn0J0/sCjivzwX9oBcwFnWaaas/kSG+J/WzLOxJHS4****
    MaxResults

    integer

    No

    The maximum number of entries to return. Valid values: 1 to 2147483647. Default value: 20.

    20
    DryRun

    boolean

    No

    Specifies whether to perform only a dry run. Valid values:

    • true: performs a dry run without modifying EPS resources.

    • false (default): sends a normal request.

    false
    ClientToken

    string

    No

    The client token that is used to ensure the idempotence of the request.

    You can use the client to generate the token, but you must make sure that the token is unique among different requests. The client token can contain only ASCII characters.

    Note

    If you do not specify this parameter, the system automatically uses the RequestId of the API request as the ClientToken. The RequestId may be different for each API request.

    02fb3da4-130e-11e9-8e44-00****
    Tag

    array<object>

    No

    The list of tags.

    You can bind up to 20 tags.

    object

    No

    Key

    string

    No

    The tag key of the resource. Once specified, the value cannot be an empty string. The tag key can be up to 128 characters in length and cannot start with aliyun or acs:. It cannot contain http:// or https://.

    TestKey
    Value

    string

    No

    The tag value of the resource. The tag value can be an empty string and can be up to 128 characters in length. It cannot contain http:// or https://.

    TestValue

    Response elements

    Element

    Type

    Description

    Example

    object

    RpcResponse

    RequestId

    string

    The request ID.

    05130E79-588D-5C40-A718-C4863A59****
    Success

    boolean

    Indicates whether the call was successful. Valid values:

    • True: successful.

    • False: failed.

    True
    Code

    string

    The response code. A value of 200 indicates success. Other values indicate failure. For more information about error codes, see error codes.

    200
    Message

    string

    The returned message.

    OK
    HttpStatusCode

    integer

    The HTTP status code.

    200
    DynamicCode

    string

    The dynamic error code.

    IllegalParamFormat.EcrId
    DynamicMessage

    string

    The dynamic error message, which is used to replace the %s in the ErrMessage return parameter.

    Note

    If ErrMessage returns The Value of Input Parameter %s is not valid and DynamicMessage returns DtsJobId, the request parameter DtsJobId is invalid.

    The param format of EcrId **** is illegal.
    AccessDeniedDetail

    string

    The access denied details.

    Authentication is failed for ****
    TotalCount

    integer

    The total number of associated resources.

    1
    MaxResults

    integer

    The maximum number of entries to return. Valid values: 1 to 2147483647. Default value: 20.

    20
    NextToken

    string

    The pagination token. Valid values:

    • If NextToken is empty, no next query exists.

    • If NextToken is returned, the value indicates the token for the next query.

    AAAAAYws9fJ0Ur4MGm/5OkDoW/Zn0J0/sCjivzwX9oBcwFnWaaas/kSG+J/WzLOxJHS4****

    AssociationList

    array<object>

    The list of associated resources.

    array<object>

    AssociationId

    string

    The associate ID between the Express Connect Router (ECR) and a VPC or TR.

    ecr-assoc-9p2qxx5phpca2m****

    RegionId

    string

    The region to which the resource belongs.

    cn-hangzhou
    OwnerId

    integer

    The Alibaba Cloud account ID to which the resource belongs.

    167509154715****
    GmtCreate

    string

    The time when the association was created. The time is displayed in UTC in the YYYY-MM-DDThh:mm:ssZ format.

    2024-01-09T12:18:23Z
    GmtModified

    string

    The time when the association was modified. The time is displayed in UTC in the YYYY-MM-DDThh:mm:ssZ format.

    2024-01-09T12:18:23Z
    Status

    string

    The deployment status of the associated resource. Valid values:

    • CREATING: being created.

    • ACTIVE: created.

    • INACTIVE: the Express Connect Router (ECR) is associated with the transit router, and the transit router is pending to attach the Express Connect Router (ECR) for routing and forwarding.

    • ASSOCIATING: being attached.

    • DISSOCIATING: being dissociated.

    • UPDATING: being modified.

    • DELETING: being deleted.

    ACTIVE
    AssociationNodeType

    string

    The type of the associated resource. Valid values:

    • VPC: virtual private cloud.

    • TR: transit router.

    VPC
    TransitRouterOwnerId

    integer

    The Alibaba Cloud account ID to which the transit router belongs.

    189159362009****

    TransitRouterId

    string

    The ID of the transit router instance.

    tr-2ze4i71c6be454e2l****

    CenId

    string

    The CEN instance ID.

    cen-5510frtx8zi54q****
    VpcOwnerId

    integer

    The Alibaba Cloud account ID to which the VPC belongs.

    146757288406****
    VpcId

    string

    The ID of the VPC-connected instance.

    vpc-2zeeaxet4i2j1a7n7****
    AllowedPrefixes

    array

    The allowed route prefix list.

    string

    The allowed route prefix.

    192.0.**.**/28
    EcrId

    string

    The Express Connect Router (ECR) instance ID.

    ecr-fu8rszhgv7623c****
    AllowedPrefixesMode

    string

    The prefix route mode. Valid values:

    • MatchMode: match mode.

    • IncrementalMode: incremental mode.

    MatchMode
    Description

    string

    The description of the associated resource.

    test

    Tags

    array<object>

    The list of tags bound to the associated resource.

    object

    Key

    string

    The tag key.

    TestKey
    Value

    string

    The tag value.

    TestValue
    TransitRouterName

    string

    The name of the transit router instance.

    test
    VpcName

    string

    The name of the VPC-connected instance.

    test

    Examples

    Success response

    JSON format

    {
  "RequestId": "05130E79-588D-5C40-A718-C4863A59****",
  "Success": true,
  "Code": "200",
  "Message": "OK",
  "HttpStatusCode": 200,
  "DynamicCode": "IllegalParamFormat.EcrId",
  "DynamicMessage": "The param format of EcrId **** is illegal.",
  "AccessDeniedDetail": "Authentication is failed for ****",
  "TotalCount": 1,
  "MaxResults": 20,
  "NextToken": "AAAAAYws9fJ0Ur4MGm/5OkDoW/Zn0J0/sCjivzwX9oBcwFnWaaas/kSG+J/WzLOxJHS4****\n",
  "AssociationList": [
    {
      "AssociationId": "ecr-assoc-9p2qxx5phpca2m****\n",
      "RegionId": "cn-hangzhou",
      "OwnerId": 0,
      "GmtCreate": "2024-01-09T12:18:23Z",
      "GmtModified": "2024-01-09T12:18:23Z",
      "Status": "ACTIVE",
      "AssociationNodeType": "VPC",
      "TransitRouterOwnerId": 0,
      "TransitRouterId": "tr-2ze4i71c6be454e2l****\n",
      "CenId": "cen-5510frtx8zi54q****",
      "VpcOwnerId": 0,
      "VpcId": "vpc-2zeeaxet4i2j1a7n7****",
      "AllowedPrefixes": [
        "192.0.**.**/28"
      ],
      "EcrId": "ecr-fu8rszhgv7623c****",
      "AllowedPrefixesMode": "MatchMode",
      "Description": "test ",
      "Tags": [
        {
          "Key": "TestKey",
          "Value": "TestValue"
        }
      ],
      "TransitRouterName": "test",
      "VpcName": "test"
    }
  ]
}

    Error codes

    HTTP status code

    Error code

    Error message

    Description
    400 MissingParam.%s The param of %s is missing. The request parameters are not specified. Please check the corresponding parameters and try again.
    400 IllegalParamFormat.%s The param format of %s is illegal. Illegal parameter format
    400 IllegalParam.%s The param of %s is illegal. Illegal parameter
    404 ResourceNotFound.EcrId EcrId not found. ECR instance does not exist

    See Error Codes for a complete list.

    Release notes

    See Release Notes for a complete list.