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 QoS.

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 QoS.

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.