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Cisco breakout DAC on FortiSwitch

I'm trying to connect an Arista 7170-64C and a FortiSwitch-148F using a Cisco 40G to 4x10G breakout cable. Both sides see the plugged in modules, but the link(s) don't come up. When I run 'get switch modules status' on the FortiSwitch, I get an 'Unsupported by module' message on the ports where the breakout cable is plugged in. Is there some setting that I need to enable to get it to work, or must I use a Fortinet-coded cable for this? Does one even exist that could bridge a 100G port to a 10G port?

Tweakbox Appvalley
Not applicable

Hello reene11, 


Thank you for using the Community Forum. I will seek to get you an answer or help. We will reply to this thread with an update as soon as possible. 



 Fortinet Community Team 



From what i understand, you are splitting the ports on Arista Switch 4x10G and one of the split cable is connecting to FSW.

Whats the speed config on Cisco and FSW? Please try to have same speed config on both sides, may be set to 10000auto or 10000full.

Is the FSW on latest version 7.0.4 ot 6.4.10?

get switch modules summary - is the module in any error or alarm state?


We can check the switch log after you connect the module to the switch.

execute log filter view-lines 1000

execute log display

diag switch physical-port summary port#


Sachit Das
ETAC Engineer
Wifi-Switching – International Support

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