HCX - Error while extending pre-created segments "Error creating NSX-T Segment. Address, overlaps with Segment path"

Products

• VMware HCX

Issue/Introduction

• You have pre-created NSX segments on the destination.
• The NSX destination contains more than 1000 segments:
  
• While extending a segment using the same subnet/gateway, the HCX Manager should detect that the segment already exists on the target/destination NSX and provide a warning. Instead, HCX Manager is not detecting the overlapping IP subnet during validation, and "Validation Completed. Submit to Proceed" is displayed:
  
• During the extension workflow, HCX Manager attempts to create a segment using the same subnet/IP, as it did not detect that the same IP subnet already exists on the target, which causes the following error: 
  

  Error creating NSX-T Segment. Address ##.##.##.##/## overlaps with Segment path=[/infra/segments/########-####-####-####-############] that has subnet ##.##.##.##/##.

• The following error is observed in /common/log/admin/app.log
  

  <timestamps> UTC [NetworkStretchService_SvcThread-2852, j: ########, s: ########, , TxId: TxId: ########-####-####-####-############] ERROR c.v.v.h.n.i.PrepareVCNetworkJobInt- Error creating nsxt Network: {
      "status": "failure",
      "statusCode": 400,
      "details": "",
      "result": {
          "httpStatus": "BAD_REQUEST",
          "error_code": 500105,
          "module_name": "Policy",
          "error_message": "Address ###.###.###.###/## overlaps with Segment path=[/infra/segments/########-####-####-####-############] that has subnet ###.###.###.###/##."
      }
  }

Environment

VMware HCX 
VMware NSX 4.1 or earlier versions
Large environment (+1000 segments)

Cause

HCX Manager is collecting NSX segments via the API, but it is unable to collect more than 1000 due to an issue with the API response observed in NSX 4.1.X, which may also affect earlier versions. This issue is not observed when the target NSX is running 4.2.x. Since the HCX Manager can't gather information for all segments (more than 1,000), you may experience issues with some segments, while others may work fine, leading to inconsistent behavior.

Resolution

This is a condition that may occur in a VMware HCX environment.

If you believe you have encountered this issue, please open a support case with Broadcom Support and refer to this KB article.

For more information, see Creating and managing Broadcom support cases.

Additional Information

You can verify the output with the API by using the following request. 

GET https://<NSX Manager>/policy/api/v1/infra/segments 


You will notice that the result_count returns 1000, even if there are more than 1000 segments present.

For more information regarding NSX API, refer to the  NSX-T Data Center REST API

Note: If this issue occurs on VMware Cloud on AWS and the validation detects the pre-created segment, refer to the KB: HCX fails to extend a pre-created segment on VMware Cloud on AWS