What are three types of packet delays that occur in a network？ （）

多项选择题Whichthreestatementsaretrueaboutthedatatrafficcharacteristicsofvoicetraffic？（）

A.latency must be kept below 150 ms
B.latency is not a concern as long as jitter is kept below 30 ms
C.voice packets do not require a specific type of queuing
D.voice packets are rather small
E.voice packets require TCP for rapid retransmission of dropped packets
F.voice packets require a fairly constant bandwidth reserved for voice control traffic as well as forthe voice payload

多项选择题WhataretwoQoSmechanismsthatareusedtopreventpacketloss？（）

A.header compression
B.payload compression
C.low latency queuing （LLQ）
D.weighted random early detection （WRED）
E.traffic policing
F.traffic shaping