CSMA/CD在CSMA的基础上增加了冲突检测功能。网络中的某个发送站点一旦检测到冲突，它就立即停止发送，并发出一串冲突码，其他站点都会(25)。

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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(71)between sending the notification and notification arriving at the source, thousands of additional(72)may arrive. In ATM network, a major tool for preventing(73)is(74)control. When a host wants a new virtual(75),it must describe the traffic to be offered and the service expected.

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To a router, a flow is a(66)of packets that share the same Characterstics, such as traveling the same(67),using the same(68),having the same kind of security, and so on. A router that supports the handling of flow labels has a(69)table. The table has an entry for each active flow label; each entry defines the(70)required by the corresponding flow label.

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