Which two statements are true about RSVP and the InServ QoS model？（）

• A、a drawback of implementing RSVP is the requirement to migrate to a supporting routing protocol
• B、RSVP uses DSCP to signal QoS requirements to routers 
• C、RSVP is a routing protocol
• D、RSVP is an IP protocol that uses IP protocol ID 46， and TCP/UDP ports 3455
• E、RSVP specifically provides a level of service for rate-sensitive and delay-sensitive traffic
• F、the flow-based approach of RSVP is ideal for large， scalable implementations such as the public internet