题目内容：
根据下列题干，回答题：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 （ 1 ）between sending the notification and notification arriving at the source, thousands of additional （ 2 ） may arrive. In ATM network , a major tool for preventing （ 3 ） is （ 4 ） control. When a host wants a new virtual （ 5 ）, it must describe the traffic to be offered and the service expected.
请选择（ 1 ）处最佳答案
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答案解析：