How to fix FortiSwitch-2048F port links not coming up

Fortiswitch 2048F port link not coming up when connecting to Fortigate 601F (10/25G ports) and Fortiswitch 648F

Solution

Diagram:

Fortigate 601F ==> Fortiswitch 2048F ==> Fortiswitch 648F

Step 1: Check the phy-mode on the Fortiswitch-2048F ports to make sure 10G/25G are used on them (this is when connecting to either FortiGate or FortiSwitch).

FortiSwitch CLI:

config switch phy-mode
set port1-port12-phy-mode 25G
set port13-port24-phy-mode 1G/10G
set port25-port36-phy-mode 25G
set port37-port48-phy-mode 25G
end

Step 2: Disable the FEC-state when connecting FortiSwitch-2048F to FortiSwitch-648F:

Fortiswitch CLI:

config switch physical-port
edit port3
set fec-state disabled
show
end

FortiGate switch-controller CLI:

config switch-controller managed-switch
edit <FSW SN>
config ports
edit port3
set fec-state disabled
show
end

Check:

diagnose switch physical-ports list port3

Step 3: FortiGate-601F 10G-25G ULL ports change (x5,x6,x7,x8 ports of the FortiGate-601F can either be set to 10G/25G).

FortiGate CLI:

config system npu
set ull-port-mode 10G or 25G
end

FortiGate will do a reboot after this change and once it comes back, the ports of the FortiGate will either have 10G or 25G speed set on them.

After these changes, the FortiSwitch-2048F links will connect to the FortiGate-601F and FortiSwitch-648F.