Isolated ports
An isolated port is a host access port in an isolated VLAN. Isolated ports can communicate on the Layer 2 level with associated promiscuous ports in the primary VLAN only.
Isolated ports cannot communicate on the Layer 2 level with any other ports in the private VLAN (PVLAN) domain, including other ports in the same isolated VLAN.
However, if the switch that has the isolated port does not have a promiscuous port, traffic from the isolated VLAN ports can traverse through interswitch link (ISL) ports (PVLAN member ports) to a switch that has a promiscuous port.