> # Upgrade and Downgrade Limitations

> The trunking and channeling feature includes the following upgrade and downgrade limitations:

> - When F port trunking or channeling is configured on a link, the switch cannot be downgraded to Cisco MDS SAN-OS Release 3.x and NX-OS Release 4.1(1b), or earlier.
> - If you are upgrading from a SAN-OS Release 3.x to NX-OS Release 5.0(1), and you have not created VSAN 4079, the NX-OS software will automatically create VSAN 4079 and reserve it for EVFP use.

> - If you have created VSAN 4079, the upgrade to NX-OS Release 5.0(1) will have no affect on VSAN 4079.
> - If you downgrade after NX-OS Release 5.0(1), the VSAN will no longer be reserved for EVFP use.

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