Shrinking NSX IP pool range fails with the error: "Unable to modify subnet subnet-X IP range X.X.X.X - X.X.X.X from this subnet is in use."

Products

• VMware NSX for vSphere

Issue/Introduction

• Shrinking NSX IP Pool range fails.
• You see the error similar to:
  
  Unable to modify subnet subnet-X IP range #.#.#.# - #.#.#.# from this subnet is in use.
   
• Same result using REST API PUT /api/2.0/services/ipam/pools/{poolId}
• In the vsm.log file, you see entries similar to:
  
  2016-05-12 10:09:59.765 PDT INFO http-nio-127.0.0.1-7441-exec-6 AuditingServiceImpl:147 - [AuditLog] UserName:'vsphere.local\administrator', ModuleName:'IPAM', Operation:'MODIFY', Resource:'subnet-1', Time:'Thu May 12 10:09:59.764 PDT 2016', Status:'SUCCESS', Universal Object:'false'
  2016-05-12 10:09:59.767 PDT WARN http-nio-127.0.0.1-7441-exec-6 RemoteInvocationTraceInterceptor:87 - Processing of VsmHttpInvokerServiceExporter remote call resulted in fatal exception: com.vmware.vshield.vsm.ipam.facade.IPAMUIFacade.updateIpPool
  com.vmware.vshield.vsm.exceptions.OperationNotPermittedException: core-services:120080:Unable to modify subnet subnet-1. IP range 192.156.208.150 - 192.156.208.155 from this subnet is in use.
  
  Note: The preceding log excerpts are only examples. Date, time, and environmental variables may vary depending on your environment.

Environment

VMware NSX for vSphere 6.3.x
VMware NSX for vSphere 6.4.x
VMware NSX for vSphere 6.2.x

Cause

This issue occurs because in NSX-v 6.4.0 and earlier versions, the IP pool range shrinkage only works if none of the IP addresses in the range are in use.

Resolution

This issue is resolved in VMware NSX for vSphere 6.4.1

Workaround:
To work around this issue if you do not want to upgrade, contact Broadcom Support and quote this Knowledge Base article ID (301322)  in the problem description.