In cluster ontap the recommended cluster switch are NetApp CN1610, and CISCO NEXUS 5596.
Morever you can use CISCO NEXUS 5010 and 5020 but these are no longer being sold.
And NeApp cluster do not support the CISCO NEXUS 5548.
your cluster is upto 12 node you can use NetApp CN1610 switch.
If your cluster is more than 12 node the recommended switch is CISCO NEXUS 5596.