This Video provides knowledge and information about the Link aggregate interface.
diag netlink aggregate name (agg_name) -- Explains this command
diag sniffer packet any 'ether proto 0X8809" 6 0 l - Explains capturing LACP only packets on Fortigate.
diag hardware devinfo nic port (portname)
LACP Modes , LACP Speed, LACP Algortihm.