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YasushiNarita
YasushiNarita
Explorer II
February 19, 2025
Question

what is VLAN ID 0 ? why cannot use VLAN ID 1?

  • February 19, 2025
  • 2 replies
  • 2588 views

Fortigate 90G FirmVer7.4.5

Default internal is VLAN ID 0.

I tried to change this VLAN ID 1,but errore poped up something like "cannont use VLAN ID 1..."

 

I want to use VLAN ID 1 ,because I want to fortigate deliver VLAN ID 1,100,200 by trunk-port to cisco L2switch.

 

How can i change VLAN ID 1 of fortigate? 

or it is not nessesary to define VLAN ID 1?

By the way, what means internal vlan id 0 is? 

 

2 replies

AEK
SuperUser
AEK
SuperUser
February 19, 2025

You need to create 3 VLAN interfaces, with VLAN 1, 100 and 200.

You do it under menu Network > Interface, click "New", then select type VLAN and the appropriate ID. The 3 interfaces must be created on the physical interface that is connected to your Cisco switch as trunk interface.

AEK
    Toshi_Esumi
    SuperUser
    Toshi_Esumi
    SuperUser
    February 19, 2025

    https://docs.fortinet.com/document/fortigate/7.6.2/fortigate-7000f-administration-guide/729353/vlan-id-1-is-reserved

    Toshi

      AEK
      SuperUser
      AEK
      SuperUser
      February 19, 2025

      8 years in FGT and I don't know this!

      I grew up in ignorance.

      AEK
      Toshi_Esumi
      SuperUser
      Toshi_Esumi
      SuperUser
      February 19, 2025

      I didn't know that either until last year when I was investigating F-series "VLAN switch"'s "trunk" port issue. Probably was not written anywhere clearly until recently.

      Toshi

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