Which two statements about the DiffServ QoS model are true？（）
- ADiffServ requires RSVP to set up a path through the network to accommodate the requested QoS.
- BNetwork traffic is identified by class， and the level of service is chosen for each class.
- CThe DiffServ model relies on a fairly simple mechanism to provide QoS over a wide range of equipment.
- DRSVP enables the DiffServ model to provide end-to-end QoS.
- EThe DiffServ model is more scalable than the IntServ model.
- FThe flow-based approach of the DiffServ model is ideal for large scalable implementations such as the public Internet.