About Port Isolation 

The Port Isolation functionality prevents local switching among ports on a NetVisor OS switch or on a pair of NetVisor OS switches configured as a cluster. 

With Port Isolation NetVisor OS disables direct communication between hosts that are part of the same Layer 2 domain and are connected to isolated ports. That has the associated security benefit that hosts cannot see each other’s MAC address and ARP requests (or replies), thus MAC or ARP spoofing attacks on other hosts are not possible (or become more difficult). 

Communication between isolated hosts can still occur through a Layer 3 device, if needed, but Access Control Lists can be used to prevent that too when necessary.