Chapter 4: Web management
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NS3550-8T-2S Industrial Managed Switch User Manual
Port isolation
When a VLAN is configured to be a private VLAN, communication between ports within
that VLAN can be prevented. Two application examples are provided in this section:
• Customers connected to an ISP can be members of the same VLAN, but they are
not allowed to communicate with each other within that VLAN.
• Servers in a farm of web servers in a Demilitarized Zone (DMZ) are allowed to
communicate with the outside world and with database servers on the inside
segment, but are not allowed to communicate with each other.
For private VLANs to be applied, the switch must first be configured for standard VLAN
operation. When this is in place, one or more of the configured VLANs can be
configured as private VLANs. Ports in a private VLAN fall into one of these two groups:
Promiscuous ports
• Ports from which traffic can be forwarded to all ports in the private VLAN.
• Ports that can receive traffic from all ports in the private VLAN.
Isolated ports
• Ports from which traffic can only be forwarded to promiscuous ports in the private
VLAN.
• Ports that can receive traffic from only promiscuous ports in the private VLAN.