Vlan on Fortigate 802.3ad Aggreg and Hardware switch

[hzchaudry60]

Hi everyone,

I’m working on a FortiGate(FortiGate F100-7.6) deployment where VLANs are currently configured under a hardware switch interface. Each switch in the network is connected to the FortiGate via individual trunk links. Now, I want to migrate to a more scalable setup using aggregate (LAG) interfaces between the FortiGate and the switches.

Here’s the challenge:

• I want to continue using the same VLANs (e.g., VLAN 10, 20, 30) across the network.

• These VLANs are already configured and working on the FortiGate’s hardware switch interface.

• I now need to connect the switches using new aggregate interfaces, but I’m not sure how to handle the VLAN configuration on the FortiGate side.

My question is:
Can I use the same VLANs (with the same IDs) on both the existing hardware switch and the new aggregate interfaces.

what's the best way to deal with this. i will have 3 switches in aggreg with the fortigate. I know the switch side configuration, only confused about the vlan config on the fortigate


FortiGate #802.3

[funkylicious]

if you create the same vlan id under a new interface/aggr it should not be a issue.

[hzchaudry60]

Hi @funkylicious  I have already tried that but i am not able to get the connectivity. i also created policies but no result.

[Toshi_Esumi]

I don't think a VLAN ID on the hardware-switch is connected to the same VLAN ID on an interface OUTSIDE of the hardware-switch, like on an independent individual port or LAG combining those independent ports based on my experience in the past. 
I think you can even configure L3 on both sides since they're separated.

You have to either do hard-cut or have L3 routing between them by changing the subnet. If you do the hard-cut while it's running, you have to remove the original VLAN, and all dependent config. It might be difficult to do. So instead, I would just change the "set interface" of the VLAN after downloading the config into a file. When you restore it with the modified config, it would reboot. Just be aware.
Also, keep the original config file handy just in case you have to revert.

Toshi


Toshi

[hzchaudry60]

Hi Thankyou for your reply. I tried creating the same vlan id under the aggreg interface. But i am not able to pass traffic. Even if i delete the vlans from the hardware switch(clarification-hardware switch on fortigate/not the cisco switch cisco side is already configured) and only create on 1 aggreg interfaces with IP address and on other Aggreg interfaces without IP address and with same vlan ID. 
the traffic pass only between 1 aggreg interface only and the Aggreg int without IP address on the vlan doesnot get traffic