I'm surprised there is still a requirement for dedicated cluster switches with 4 nodes when using a software defined storage.
I haven't seen this mentioned in any of the Ontap Select design guides. Considering the network is already virtualized it seems odd that specifc network switches are required when the Ontap select node still thinks its connected to a vSwitch.
If you are setting up a two-node cluster, you can set up the cluster in either a two-node switchless configuration without cluster interconnect switches, or a switched configuration that uses the cluster interconnect switches.
Currently Select only supports 1 node (single node) or 4 node cluster configurations. The 4-node config requires an internal network on 10Gb NICs that functions as the interconnect - but you can use the 10Gb connections for data as well if you want - just separate traffic with VLANs/portgroups on the same vSwitch.
Look for 2 node in a future release.
I suspect a 2 node setup will still require some form of "witness" solution so probably why it's not currently available.
Any news on this 2-node only cluster? On roadmap? There are way today to provide witness if required other then putting additional cluster in place :-). Smaller vendors are doing it over NFS share or just putting small service or vm ouside the cluster like StoreVIrtual FOM.