Technical Tip: Configuration Requirements of FN-TRAN-SX Transceiver on FortiGate with Cisco ASA or Nexus

If an SFP port on the FortiGate uses an FN-TRAN-SX transceiver and is connected to a Cisco ASA firewall or Nexus Switch, but the link does not come up, ensure the configuration is as follows:

• The FortiGate interface is configured with 'set mediatype gmii'.
• The FortiGate interface speed is set to 1000full, which disables auto-negotiation.
• The Remote device interface has speed auto-negotiation disabled ('speed nonegotiate' on Cisco devices).

Example FortiGate configuration:

config system interface
    edit "port24"
        set vdom "root"
        set type physical
        set mediatype gmii 
        set speed 1000full
    next
end

If the remote device's interface is using an SFP module, it is recommended to set the media-type to SFP on the remote side: see the third-party CLI reference, CLI Book 1: Cisco ASA Series General Operations CLI Configuration Guide. SFP media-type may not be available on all ASA models.

FortiGate models with shared media ports do not support 'set mediatype' configurations. See the article Technical Tip: Understanding Shared Media interfaces on the FortiGate for general information on Shared Media interfaces.

Note: On devices like 3201F, once the speed is set to 1000full (1G), the media type lr and sr is no longer selectable or configurable. Only 'gmii' or 'sgmii' can be seen as a media type.