Administrator Guide

Private VLAN (PVLAN)
The private VLAN (PVLAN) feature of the Dell Networking operating software.
Private VLANs extend the system security suite by providing Layer 2 isolation between ports within the same private VLAN. A
private VLAN partitions a traditional VLAN into subdomains identified by a primary and secondary VLAN pair. The private VLAN
implementation is based on RFC 3069.
For more information, see the following commands. The command output is augmented in the Dell Networking OS version
7.8.1.0 at later to provide PVLAN data:
● show arp
● show vlan
Private VLAN Concepts
Primary VLAN:
The primary VLAN is the base VLAN and can have multiple secondary VLANs. There are two types of secondary VLAN —
community VLAN and isolated VLAN:
● A primary VLAN can have any number of community VLANs and isolated VLANs.
● Private VLANs block all traffic to isolated ports except traffic from promiscuous ports. Traffic received from an isolated port
is forwarded only to promiscuous ports or trunk ports.
Community VLAN:
A community VLAN is a secondary VLAN of the primary VLAN:
● Ports in a community VLAN can talk to each other. Also, all ports in a community VLAN can talk to all promiscuous ports in
the primary VLAN and vice versa.
● Devices on a community VLAN can communicate with each other using member ports, while devices in an isolated VLAN
cannot.
Isolated VLAN:
An isolated VLAN is a secondary VLAN of the primary VLAN:
● Ports in an isolated VLAN cannot talk to each other. Servers would be mostly connected to isolated VLAN ports.
● Isolated ports can talk to promiscuous ports in the primary VLAN, and vice versa.
Port Types:
● Community port: A community port is a port that belongs to a community VLAN and is allowed to communicate with other
ports in the same community VLAN and with promiscuous ports.
● Isolated port: An isolated port is a port that, in Layer 2, can only communicate with promiscuous ports that are in the same
PVLAN.
● Promiscuous port: A promiscuous port is a port that is allowed to communicate with any other port type.
● Trunk port: A trunk port carries VLAN traffic across switches:
○ A trunk port in a PVLAN is always tagged.
○ A trunk port in Tagged mode carries primary or secondary VLAN traffic. The tag on the packet helps identify the VLAN to
which the packet belongs.
○ A trunk port can also belong to a regular VLAN (non-private VLAN).
Topics:
• ip local-proxy-arp
• private-vlan mode
• private-vlan mapping secondary-vlan
• show interfaces private-vlan
• show vlan private-vlan
• switchport mode private-vlan
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