# Rolling back NSNA mode to default mode

After you enable NSNA on the Ethernet Routing Switch 5000 Series, NSNA dynamically changes the following port settings:

- VLAN settings

- QoS parameters

- Spanning Tree configuration

After you disable NSNA, the changes to those port settings are rolled back automatically, and pre-NSNA settings are applied on the port.

There is, however, one exception: When NSNA is enabled on a port, STP runs in FAST START mode to enable faster convergence. The Spanning Tree state of the LAN port can stay in FAST START mode when NSNA is disabled if the client ports were set to Normal Learning in the pre-NSNA state. If the pre-NSNA Spanning Tree state was Fast Learning or disabled, the port rolls back correctly.

If you had physically moved existing users from a legacy switch to an NSNA-enabled switch, the only task you must complete to roll back port settings is to physically reconnect the users to the legacy switch.