In the design of a QoS solution， which two factors should be taken into consideration？（）
- A On congested links， all forms of traffic will require some form of QoS.
- B All traffic types and requirements should be examined to determine the number of traffic classes required.
- C In the implementation of link efficiency mechanisms on links that typically transport relatively large packets， header compression will be most efficient.
- D In the implementation of link efficiency mechanisms on links that typically transport relatively small packets， header compression will be most efficient.
- E In the implementation of link efficiency mechanisms on links that typically transport relatively small packets， payload compression will be most efficient.
- F Payload compression provides more available bandwidth and reduces processing delay time.