New Undocumented Feature in NSX-T 3.2 MC

Migration Coordinator (MC) is VMware’s tool to migrate from NSX Data Center for vSphere (NSX-V) to NSX-T Data Center (NSX-T). Last week I was helping a customer migrating their Distributed Firewall Configuration from NSX-V to NSX-T 3.2 and we were presented with a new step in the process called “Prepare Infrastructure”. I have never seen this step in NSX-T 3.1 and earlier, and was surprised to see it now since I had checked the documentation for any changes to the process.

The new step looks like this:

The documentation said that no changes would be done to NSX-V during the migration so I was trying to find anyone able to tell me what this step would do. Finally someone at VMware could to tell me that this step would create temporary IP Sets in NSX-V to to maintain security during the migration. When you migrate a VM from one vCenter (NSX-V) to another vCenter (NSX-T), the VM will no longer be included in the Security Groups in NSX-V since the object is not longer present there. Before NSX-T 3.2 we had to create these IP Sets manually in NSX-V so this is a welcome feature in NSX-T 3.2 MC. MC has already been creating temporary IP sets in NSX-T for some time. More details on this can be found here.

The latest version of the NSX-T 3.2 docs has now been updated with the missing information:

“In the Prepare Infrastructure step, temporary IP sets will be added to NSX-V if the NSX-V security groups are used in a distributed firewall rule. This is required to maintain security while the VMs are migrated from NSX-V to NSX-T. After the migration, during the finalize infrastructure phase, the temporary IP sets will be deleted.
You can skip the Prepare Infrastructure step. However, doing so may compromise security until the finalize infrastructure phase is complete.”

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