A、A received IP packet is forwarded based on the IP destination address and the packet is sent as an IP packet.

B、An IP destination exists in the IP forwarding table. A received labeled packet is dropped because the label is not found in the LFIB table.

C、There is an MPLS label-switched path toward the destination. A received IP packet is dropped because the destination is not found in the IP forwarding table.

D、A received IP packet is forwarded based on the IP destination address and the packet is sent as a labeled packet.

E、A received labeled IP packet is forwarded based upon both the label and the IP address.

F、A received labeled packet is forwarded based on the label. After the label is swapped，the newly labeled packet is sent.