Which two statements about the DiffServ QoS model are true？（）

A. DiffServ requires RSVP to set up a path through the network to accommodate the requested Qo
B. Network traffic is identified by class， and the level of service is chosen for each class.
C. The DiffServ model relies on a fairly simple mechanism to provide QoS over a wide range of equipment.
D. RSVP enables the DiffServ model to provide end-to-end Qo
E. The DiffServ model is more scalable than the IntServ model.
F. The flow-based approach of the DiffServ model is ideal for large scalable implementations such as the public Internet.