PVLAN member port (Also called Interswitch Link [ISL] ports)

A PVLAN member port (ISL port) is required in multi-switch PVLAN configurations to span the switches. The PVLAN member port will automatically become a member of all VLANs within the PVLAN (that is, the primary VLAN, the community VLANs and the isolated VLAN), and it carries traffic from the primary VLAN and all secondary VLANs.

A primary VLAN port can either act as a promiscuous port or PVLAN member port (ISL port). By default, the primary VLAN port acts as promiscuous port. To make it a PVLAN member port (or ISL port), un-configure the port as promiscuous port from the interface context.