Host preparation is the process in which the NSX Manager 1) installs NSX kernel modules on ESXi hosts that are members of vCenter clusters and 2) builds the NSX control-plane and management-plane fabric. NSX kernel modules packaged in VIB files run within the hypervisor kernel and provide services such as distributed routing, distributed firewall, and VXLAN bridging capabilities.

To prepare your environment for network virtualization, you must install network infrastructure components on a per-cluster level for each vCenter server where needed. This deploys the required software on all hosts in the cluster. When a new host is added to this cluster, the required software is automatically installed on the newly added host.

If you are using ESXi in stateless mode (meaning that ESXi does not actively persist its state across reboots), you must download the NSX VIBs manually and make them part of the host image. You can find the download paths for the NSX VIBs from the page: https://<NSX_MANAGER_IP>/bin/vdn/ Be aware that download paths can change for each release of NSX. Always check the https://<NSX_MANAGER_IP>/bin/vdn/ page to get the appropriate VIBs. See Deploying VXLAN through Auto Deploy for more information.

Register vCenter with NSX Manager and deploy NSX controllers.

Verify that DNS reverse lookup returns a fully qualified domain name when queried with the IP address of NSX Manager. For example:

Server:  localhost

Name:    nsxmgr-l-01a.corp.local

Verify that hosts can resolve the DNS name of vCenter server.

Verify that hosts can connect to vCenter Server on port 80.

Verify that the network time on vCenter Server and ESXi hosts is synchronized.

For each host cluster that will participate in NSX, verify that hosts within the cluster are attached to a common VDS.

For instance, say you have a cluster with Host1 and Host2. Host1 is attached to VDS1 and VDS2. Host2 is attached to VDS1 and VDS3. When you prepare a cluster for NSX, you can only associate NSX with VDS1 on the cluster. If you add another host (Host3) to the cluster and Host3 is not attached to VDS1, it is an invalid configuration, and Host3 will not be ready for NSX functionality.

If you have vSphere Update Manager (VUM) in your environment, you must disable it before preparing clusters for network virtualization. For information on how to check if VUM is enabled and how to disable it if necessary, see

Before beginning the NSX host preparation process, always make sure that the cluster is in the resolved state---meaning that the Resolve option does not appear in the cluster's Actions list.

For example:

The Resolve option sometimes appears because one or more hosts in the cluster need to be rebooted.

Other times the Resolve option appears because there is an error condition that needs to be resolved. Click the Not Ready link to view the error. If you can, clear the error condition. If you cannot clear an error condition on a cluster, one workaround is to move the hosts to a new or different cluster and delete the old cluster.

Any process that removes one or more VIBs from a host requires a host reboot. Processes that remove VIBs include NSX upgrades, removing the NSX Manager plug-in from vCenter, removing a host from a cluster that has been prepared for NSX, and manually removing NSX VIBs from a host. When a host needs to be rebooted, the reboot required tag appears in the Hosts and Clusters view. For example:

The required reboot does not happen automatically. Before rebooting a host, power off or move its VMs (or allow DRS to move them). Then, on the Host Preparation tab, click the Resolve option in the Actions list. The Resolve action places the hosts into maintenance mode, reboots the hosts, and then removes the hosts from maintenance mode. If you powered off a host's VMs, you must manually power them back on.


In vCenter, navigate to Home > Networking & Security > Installation and select the Host Preparation tab.

For example:


For all clusters that will require NSX logical switching, routing, and firewalls, click the gear icon and click Install.

A compute cluster (also known as a payload cluster) is a cluster with application VMs (web, database, and so on). If a compute cluster will have NSX switching, routing, or firewalls, you must click Install for the compute cluster.

In a shared "Management and Edge" cluster (as shown in the example), NSX Manager and controller VMs share a cluster with edge devices, such as distributed logical routers (DLRs) and edge services gateways (ESGs). In this case, it is important to click Install for the shared cluster.

Conversely, if Management and Edge each has a dedicated, non-shared cluster---as is recommended in a production environment---click Install for the Edge cluster but for the Management cluster.


While the installation is in progress, do not deploy, upgrade, or uninstall any service or component.


Monitor the installation until the Installation Status column displays a green check mark.

If the Installation Status column displays a red warning icon and says Not Ready, click Resolve. Clicking Resolve might result in a reboot of the host. If the installation is still not successful, click the warning icon. All errors are displayed. Take the required action and click Resolve again.

When the installation is complete, the Installation Status column displays 6.2 Uninstall and the Firewall column displays Enabled. Both columns have a green check mark. If you see Resolve in the Installation Status column, click Resolve and then refresh your browser window.

VIBs are installed and registered with all hosts within the prepared cluster:



To verify, SSH to each host and run the esxcli software vib list | grep esx command. In addition to displaying the VIBs, this command shows the version of the VIBs installed.

[root@host:~] esxcli software vib list | grep esx
esx-vsip      6.0.0-0.0.2732470    VMware  VMwareCertified   2015-05-29
esx-vxlan     6.0.0-0.0.2732470    VMware  VMwareCertified   2015-05-29

After host preparation, a host reboot is not required.

If you add a host to a prepared cluster, the NSX VIBs automatically get installed on the host.

If you move a host to an unprepared cluster, the NSX VIBs automatically get uninstalled from the host. In this case, a host reboot is required to complete the uninstall process.