What is the behavior of a port in a private-vlan pimary vlan that isn't set to promiscuous?

2 Answers 2


you need to consider the next facts
1- A private VLAN domain has only one primary VLAN. Each port in a private VLAN domain is a member of the primary VLAN; the primary VLAN is the entire private VLAN domain.

2- Secondary VLANs provide isolation between ports within the same private VLAN domain. The following two types are secondary VLANs within a primary VLAN: Secondary Isolated VLAN & Secondary Community VLANs where

  • Isolated VLANs—Ports within an isolated VLAN cannot communicate directly with each other at the Layer 2 level.
  • Community VLANs—Ports within a community VLAN can communicate with each other but cannot communicate with ports in other community VLANs or in any isolated VLANs at the Layer 2 level

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3- A promiscuous port can serve only one primary VLAN, one isolated VLAN, and multiple community VLANs. Layer 3 gateways are typically connected to the switch through a promiscuous port.

SO other port types (isolated port and community port) are the only available port types if this port is not promiscuous where

  • An isolated port is a host port that belongs to an isolated secondary VLAN. This port has complete isolation from other ports within the same private VLAN domain, except that it can communicate with associated promiscuous ports
  • Community—A community port is a host port that belongs to a community secondary VLAN.Community ports communicate with other ports in the same community VLAN and with associated promiscuous ports
  • I think is a very fully formed answer thank you.
    – skrap3e
    Nov 14, 2015 at 17:38
  • But one question, isn't it strange that you have to tell a port in the primary vlan that it is promiscuous? Maybe even in the primary vlan a port can be community or isolated?
    – skrap3e
    Nov 14, 2015 at 17:44

It is depend on the private vlan type:
1- if it is community vlan member will be able to communicate with the promiscuous port and other ports in the same community vlan.
2- if it is isolated vlan member will be able to communicate with promiscuous port only

  • I stated in the question that this was a port specifically in the primary vlan. Can the primary vlan be community or isolated? I don't believe so...
    – skrap3e
    Nov 14, 2015 at 17:45

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