When should traffic shaping be implemented on Frame Relay PVCs?()
A、When you want to drop excess traffic above the CIR
B、When there is a speed mismatch between the central site and the remote site
C、When using Frame Relay SVCs
D、When over-subscribing the central site link
E、When LLQ is implemented on the Frame Relay PVC
F、When Multilink PPP LFI is implemented on the Frame Relay PVC