link aggregation between fortigate and cisco switch

If the link doesn' t come up, check the configured LACP mode on the switch. I had this issue before and the mode had to be changed to ' Passive' .

FWIW only One side needs to be active but both sides can be active and it will work. I' ve created a post with samples for the most common firewalls. http://socpuppet.blogspot.com/2014/03/increasing-your-firewall-capacity-via.html I' m betting you didn' t change the channel protocol to LACP. Post copies of the switch cfg and fortigate if you need help. BTW: These same units works very will with cisco IOS and NX-OS switches & with or without vPC.