Same VLAN on 3 vdoms connected to the same port

[zLade]

Hello everyone,

I'm trying to configure this setup but my fortigate 100d reject me because it doesn't want to configure the same vlan id.

It works if there is 3 differents vlan id but it's not that i want because there a switch with multiple network devices connected to this firewall which communicates on this vlan.

How can i solve this please ?

Thanks !

[hallodri]

AFAIK this is only possible with a VDOM in transparent mode in front of the other VDOMs. Each VDOM needs a vlink to the transparent VDOM. But I have never tried this.

[zLade]

Ok thanks you, but transparent mode is not really efficient i think for my usage.

Someone as another solution ?

[Sylvia]

I agree with hallodri - it's not possible with the same vlan id on the same interface.

Assume that a packet flagged with vlan id 50 arrives at port1. How should the Fortigate decide to which VDOM this packet belongs?

So, different vlan id or different ports...

[emnoc]

You can't do that and I don't see how you could expect that to work. a vlanid is unique per sub-interface. Why must you use vlanid 50 on the same port and to the same VDOMs? Please explain your objective and goal, any maybe we can find  an alternative solution.

A vlan-tag is a layer2 and if you tried to craft  a subinterface reusing a  vlanid & the sub-intf references the same physical interface, the fortigate will complain.

i.e ( warning )

vlanid and physical interface must be a unique pair

Keep in mind you can't really run 802.1q tag over vlink-interface ( ethernet type )  but some  FTNT documents reference this is available but YMMV by FortiOS and model type.

Ken