A virtual port channel (vPC) allows links that are physically connected to two different Cisco Nexus devices to appear as a single port channel to a third device. Which are the mandatory steps for configuring vPC? ()   
A、 Enable feature vPC
B、 Define domains
C、 Establish peer keepalive connectivity
D、 Create a peer link
E、 Configure the peer link as a trunk port
F、 Create port channels and vPCs
H、 Define port channel load-balancing method
I、 Make sure configurations are consistent