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New Contributor III

Trunk Port on FortiSwitch

Hello Dears


I am trying to perform trunk with cisco interface on fortinet switch 148F , i did the configureation required for trunk as show below but it is not working anyone can help plz? i think the issue is unable to change to dot.1q it's working isl


config switch trunk edit "Trunk" set members "port2" next end




There is a difference between the naming of different vendors. If you have only one physical port connecting the switches you don't need to configure a trunk in FSW. The term "trunk" in FSW is for link aggregation.

Just set a native VLAN and the allowed VLAN that you need on the uplink port.


From Cisco side you have to configure the interface as trunk mode (switchport mode trunk) set the native VLAN and allow the VLANs that you need to pass.


Take a look at another related discussion:

- Emirjon
If you have found a solution, please like and accept it to make it easily accessible for others.

hello dear


i did that but it is also not working


Dont configure the port as a trunk. You simply just need to allow the VLANs you want to pass.


Ignore the concept of access and trunk ports - thats not applicable here. Trunk, as mentioned above, is set to do LAG.

New Contributor III


I did the configuration like that but no luck


Can you show cisco config?

New Contributor III

SW(config)#interface g1/0/24

SW(config-if)#switchport mode trunk

SW(config-if)#switchport trunk allowed vlan 21

SW(config-if)#switchport nonegotiate


Okay - so you are only allowing vlan 21 on the Cisco side, but allowing 1-4000 on the FSW - is this by design?


If so - where does the SVI for VLAN 21 live? What is not working?

New Contributor III

The SVI on other device trying to reach a user on VLAN 21 AS SHOWNUntitled.png


I see also the switch is not being added to fortigate firewall controller it is looks offline


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