Which two options are reasons for using traffic classification?（）

A.to use the classification to route traffic
B.to use the classification to reorder packets from various sources
C.to use the classification to discard malformed packets
D.to use the classification to provide the configured service level

A.after a packet is identified by a multifield classifier
B.after the traffic passes though a shaper
C.prior to ingress policing of traffic
D.while the packet is stored in the switching fabric of the router