> # Manually Assigning FlexAttach Virtual pWWN

> You can manually assign a WWN to the interface, without generating it through the switch. Several checks are done by the NPV core to ensure the uniqueness of virtual pWWNs in the switch. When duplicate virtual pWWNs are configured, the subsequent logins are rejected by the NPV core switch.

> ## Prerequisites

> - Some ports may be in automode, some in manual mode, and the virtual pWWNs need not be assigned.
> - The port must be in a shut state when a virtual pWWN is assigned.

> ## Restrictions

> - The interface mentioned in the interface value must be in a shut state.

> ## Detailed Steps

> To enable virtual pWWN on each interface manually, follow these steps:

> 1. In the Physical Attributes pane, expand Switches > FC Services > N_Port Virtualizer (NPV) > Flex Attach.

> The FlexAttach configuration pane appears to the right.

> 2. Click the Virtual pWWNs tab.

> The Virtual pWWN tab view displays a list of the interfaces.

> 3. Check the Auto check box to automatically generate the virtual pWWN value for the selected interface.

> The virtual port WWN value for the selected interface in DCNM-SAN is automatically generated.

> Copyright 2010-2013, Cisco Systems, Inc. All rights reserved.