Troubleshooting Tip: SFP/SFP+/QSFP link is not coming up after upgrading from FortiOS 7.4.7 to 7.4.8

In previous FortiOS versions (before v7.4.8), the 10 Gbps speed can be configured as below:

CLI:

config system interface
    edit "portX"
        set type physical
        set mediatype cr
        set speed 10000auto
    next
end

The mediatype 'cr' is used to configure QFP/SFP+/QSFP modules and Direct Attach Copper (DAC) cables. The mediatype 'cr' is required for media-flexible interfaces such as SFP+/QSFP+ modules and can operate with different types of physical media using the same interface.

After performing an upgrade to FortiOS 7.4.8, a 10G interface configured with mediaytpe 'cr' might remain down even though another interface with an identical configuration comes up correctly.

As a workaround, manually set the interface speed to 10G full which will cause the interface to come up and restore connectivity.

CLI:

config system interface

    edit "portX"

        set type physical

     set mediatype cr

     set speed 10000full

    next

end

This can happen if the media type is set to 'cr' but the actual SFP/SFP+/QSFP module is 'sr' or 'lr'.

Before FortiOS 7.4.8, the configured media type was not strictly enforced against the actual physical media. As a result, the link could still come up even if an incorrect media type was configured on the interface.

In earlier FortiOS versions prior to 7.4.8, link behavior with an incorrect media type was inconsistent - the interface might come up in some cases and fail in others.

Starting with FortiOS 7.4.8, this behavior has changed. The media type configuration is now strictly validated, and if the configured media type does not match the actual physical media, the interface will not come up.

Related documents:

Technical Tip: Setting FortiGate port media type

Media type for interfaces that support transceiver modules