Technical Note: SLBC - Speed setting of blackplane fabric interfaces

Description
The article describes the correct method to set the speed of the FortiController backplane fabric interface

Solution
The speed setting depends on the FortiGate hardware:
    - FG5144C Chassis supports the 40G backplane.
    - If the FortiController is a FT5903C (or FT5913C) and the workers blades are FGT5001D or FG5001C, then the backplane fabric interfaces must be set to 40G

FortiController FG5144C configuration :

C1-S1 # config switch fabric-channel physical-port
(physical-port)# edit slot-3 
(slot-3)# set speed 40000full
(slot-3)# end

FortiGate configuration :

C1-S3 (global) # conf sys int
C1-S3 (interface) # edit elbc-ctrl/1
C1-S3 (elbc-ctrl/1) # set speed 40000full
C1-S3 (elbc-ctrl/1) # next
C1-S3 (interface) # edit elbc-ctrl/2
C1-S3 (elbc-ctrl/2) # set speed 40000full
C1-S3 (elbc-ctrl/2) # end

Other hardware combinations do not support 40G backplane, therefore the backplane fabric interfaces must be set to 10G :

FortiController 5103B configuration :

C1-S1 # config switch fabric-channel physical-port
(physical-port)# edit slot-3 
(slot-3)# set speed 10000full
(slot-3)# end

FortiController 5903C/5913C configuration :

C1-S1 # config system global
(global)# set fabric-backplane-port-10g-mode enable
WARNING: Enabling fabric channel backplane port 10G mode will clear the existing interface configuration and reboot system.
Do you want to continue? (y/n)y
(global)# end

C1-S1 # config switch fabric-channel physical-port
(physical-port)# edit slot-3 
(slot-3)# set speed 10000full
(slot-3)# end

FortiGate configuration :

C1-S3 (global) # conf sys int
C1-S3 (interface) # edit elbc-ctrl/1
C1-S3 (elbc-ctrl/1) # set speed 10000full
C1-S3 (elbc-ctrl/1) # next
C1-S3 (interface) # edit elbc-ctrl/2
C1-S3 (elbc-ctrl/2) # set speed 10000full
C1-S3 (elbc-ctrl/2) # end