Troubleshooting Tip: Troubleshooting LACP PortChannel issues after firmware upgrade on FortiGate

Description

This article describes the troubleshooting steps for LACP PortChannel issues after a firmware upgrade on FortiGate. The user may experience problems with physical ports forming a PortChannel after upgrading the firmware from version 7.4.4 to 7.4.5.

Scope

FortiGate.

Solution

To troubleshoot LACP PortChannel issues after a firmware upgrade on FortiGate, follow these steps:

1. Verify the PortChannel configuration and ensure that the physical ports are correctly assigned to the PortChannel.

2. Check the speed and duplex settings of the physical ports and ensure they match the requirements of the PortChannel. In FortiOS v7.4.5, a new feature introduces an automatic option that dynamically adjusts port speed, which is the new default on certain platforms. Because LACP requires all member interfaces to operate at the same speed and duplex, interfaces negotiating different speeds while set to 'auto' will break the PortChannel. If the member ports are failing to negotiate the same speed automatically, manually configure the speed on all member ports to match. Run the following commands to hardcode the speed (example setting to 1000full):
   
   

config system interface 
edit <port_name> 
set speed 1000full 
next 
end

3. Run the following command:

diagnose sys lacp stats 

This can be used to check the LACP statistics and verify that the ports are correctly negotiated.

4. Run the following command:

 diagnose sys lacp config 

To check the LACP configuration and verify that the ports are correctly configured.

5. If the issue persists, try changing the physical ports that form the PortChannel to different ports, as the problem may be specific to certain ports.

If it matches, this is part of a new feature 961038 included in FortiOS v7.4.5. See New features or enhancements.