Dell M6220 User Configuration Manual page 573

Isolated Ports
An endpoint connected to an isolated port is allowed to communicate with
endpoints connected to promiscuous ports only. Endpoints connected to
adjacent isolated ports cannot communicate with each other.
Community Ports
An endpoint connected to a community port is allowed to communicate with
the endpoints within a community and can also communicate with any
configured promiscuous port. The endpoints that belong to one community
cannot communicate with endpoints that belong to a different community, or
with endpoints connected to isolated ports.
Private VLAN Operation in the Switch Stack and Inter-switch Environment
The Private VLAN feature is supported in a stacked switch environment. The
stack links are transparent to the configured VLANs; thus, there is no need for
special private VLAN configuration beyond what would be configured for a
single switch. Any private VLAN port can reside on any stack member.
To enable private VLAN operation across multiple switches that are not
stacked, trunk ports must be configured between the switches to transport
the private VLANs. The trunk ports must be configured with the
promiscuous, isolated, and community VLANs. Trunk ports must also be
configured on all devices separating the switches.
In regular VLANs, ports in the same VLAN switch traffic at L2. However, for a
private VLAN, the promiscuous port forwards received traffic to secondary
ports in the VLAN (isolated and community). Community ports forward
received traffic to the promiscuous ports and other community ports using
the same secondary VLAN. Isolated ports transmit received traffic to the
promiscuous ports only.
The ports to which the broadcast traffic is forwarded depend on the type of
port on which the traffic was received. If the received port is a host port,
traffic is broadcast to all promiscuous and trunk ports. If the received port is a
community port, the broadcast traffic is forwarded to all promiscuous, trunk,
and community ports in the same secondary VLAN. A promiscuous port
broadcasts traffic to other promiscuous ports, isolated ports, and community
ports.
573
Configuring VLANs