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.