Issue Summary: FortiGate 200F & FortiSwitch Connectivity Problems

[MinasTtirittis]

I'm currently facing network issues involving a FortiGate 200F (firmware version 7.4.8) and two FortiSwitches (models S548 and S458), both running version 7.6.2.

Over the past three weeks, since upgrading the switches to 7.6.2, the network has become slow, intermittently unresponsive, and frequently disconnects devices.

Additionally, when accessing the topology view, not all switch-to-switch connections are visible or properly displayed.

[Richie_C]

Hi @MinasTtirittis 

Its difficult to know what is happening here. Maybe some of the following information would help to diagnose the problem:

• Are there any switch events in the logs?
• Are the switches in FortiLink mode or standalone?
• Features being used, such as MCLAG, L3 routing, NAC.....

Regards

[MinasTtirittis]

Hi @Richie_C 

Yes, the switches are configured in FortiLink mode, and the first two are running in an MCLAG setup.

Please let me know if you need any specific logs or details regarding features like NAC or L3 routing.

Regards,

[Richie_C]

Ok, I would start by checking the config and status of the MCLAG. The following commands should give you an idea of the status:

diagnose switch-controller switch-info mclag list 
diagnose switch-controller switch-info mclag icl

You should make sure that the correct interfaces are recognised as either MCLAG or ICL interfaces. 

You can also check the status of the link aggregation interfaces. The following guide is a good reference:

https://community.fortinet.com/t5/FortiGate/Technical-Tip-Initial-troubleshooting-steps-for-LACP-Lin...

Regards

Richard  

[Richie_C]

For the logs. It would be interesting to know if there are any interfaces flapping or spanning tree events to start with.

[HarryTran]

For "not all switch-to-switch connections are visible or properly displayed.", it runs in to a known bug 1174647