Before VXLAN gained mass adoption, vCloud Director relied on vCloud network isolation (VCDNI) technology to provide network isolation for virtual machines. Beginning with vCloud Director 8.10, support for VCDNI networks has been deprecated in favor of the VXLAN standard, which provides equivalent isolation capabilities and many additional features. Service providers are encouraged to migrate their legacy VCDNI networks to VXLAN technology. vCloud Director 8.20 automates this migration on a per-network-pool basis. This is a simple, one-button process. To ensure a smooth migration, take a few minutes to understand your existing VCDNI networks and the VMs that connect to them.

IMPORTANT: This migration is not supported for VCDNI network pools hosted on vSphere 6.5. After you upgrade vCloud Director to 8.20, complete this migration before you upgrade any attached vCenter servers to vSphere 6.5.

Migration is enabled in the vCloud Director Web Console by a button labeled Migrate to VXLAN on the Network tab of the Organization VDC Properties page. In the vCloud API, migration is enabled by a POST request to the migrateVcdniToVxlan link in the VDC. The button and link do not appear if the organization VDC does not contain any VCDNI networks.

Internally, the migration workflow follows these steps:

1. It creates a list of Edge Gateways in the organization VDC connected to a network in the VCDNI network pool.
2. For each Internal gateway interface, it retrieves a list of all VM NICs connected to a network in the VCDNI network pool.
3. For each unique network in the list, it creates a VXLAN isolated network in the organization VDC and update the vCloud Director database to replace the backing VCDNI network with a VXLAN network.
4. It updates the gateway interface to use a new DVPortgroup in NSX.
5. It reconfigures the VM so that its NICs connect to the new vCloud Director VXLAN network. This reconfiguration takes place whether or not the VM is powered on.

Prerequisites

• Verify that all NSX edges in the system are at version 5.5.4 or later.
• Verify that all vCenter servers registered to vCloud Director are running vSphere 6.0 or earlier.
  
• Verify that your existing vSphere networks do not exceed supported maximum values for settings such as portgroups and vNics per DV switch.
  
• If any of the VCDNI networks to be migrated has more than 128 VMs connected to it, increase the size of the connection pool for the vCloud Director database to a size that can handle the high level of concurrency required by this operation. You can do this by changing the global property database.pool.maxActive to a value of 200.
• Ensure that users do not access any VMs that are connected to a VCDNI network while the migration is in progress.
  

• After the migration is complete, redeploy all migrated edges to remove stale values from the edges' .vmx files.