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If I had a private vlan on my switch, can it communicate with a 'normal' vlan on that same switch ?

Is it only between secondary private vlan that communication is restricted ? It seems to be the case, but somehow I am still in doubt.

Diagram

Would Host1 and Host2 be able to communicate here ?

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  • Please edit your question to include the router and switch configurations.
    – Ron Maupin ♦
    Jun 24, 2019 at 17:08
  • Configuration is irrelevant. This is a theoretical question. I'm asking if it is possible or not.
    – user59345
    Jun 24, 2019 at 17:11
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    "Configuration is irrelevant." Are you asking a simple Yes/No question? We would need the network device models and configurations. What the device models are and how they are configured matters and is very relevant. Each vendor does this differently, and some vendors do not even have private VLANs.
    – Ron Maupin ♦
    Jun 24, 2019 at 17:17

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If I had a private vlan on my switch, can it communicate with a 'normal' vlan on that same switch ?

Given a Cisco switch, the answer is No. That is the whole point of private VLANs.

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According to the answer I found here : https://community.cisco.com/t5/switching/communication-between-the-secondary-community-vlans-hosts/td-p/2648508

... this seems possible based on the design I have given.

[Community Vlans] communication over the promisc port would be allowed only if the device connected to that promisc port was willing to do hairpin routing - that is, receive and forward a packet back the same interface. Usually, you do not want your different community VLANs to communicate to each other - that is why you created them in the first place - so you'd usually make sure that whatever device is connected to a promisc port, it does not do routing or is prevented from hairpin routing via an ACL, for example.

I have also asked a CCIE colleague which just confirmed to me that communication between these two vlans would work.

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  • As I explained, it depends on the vendor and configuration. If you are not trunking to the router, then, no, it will not work, but it really depends on how you have configured the network devices.
    – Ron Maupin ♦
    Jun 24, 2019 at 18:23

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