If you have multiple core and switch redudency, upstream switch failing should not be a problem in your network.
Ontap is not designed to handle such failure. that should be handled in your network design.
In a NAS environment, netapp controller is not aware or keeping track of the client status until client request reach netapp.
Let the controller do what it disigned/suppose to do rather than trying to fix everything with it.
Here is some failover policy you can configure on your LIFs..
https://library.netapp.com/ecmdocs/ECMP1636021/html/GUID-92CC5F58-5EB8-4E2D-88F0-FA2F740062E0.html
And I can gurantee none of them handle an upstream switch failure.
-robin.