In low-speed network, it is usually adequate to wait for congestion to occur and then react to it by telling the source of packets to slow down. In high-speed networks, this approach often works poorly, because in the (61) between sending the notification and notification arriving at the source, thousands of additional (62) may arrive. In ATM network, a major tool for preventing (63) is (64) control. When a host wants a new virtual (65) , it must describe the traffic to be offered and the service expected.

A．packets

B．cells

C．message

D．files

合理化包装的原则有（）。

A.标准化包装原则

B.包装单位大型化原则

C.包装机械化原则

D.包装成本低廉化原则

E.绿色包装原则