必威体育精装版通信与电子信息工程专业英语Expanding_reading_Asynchronous_Transfer_Mode.docxVIP

Asynchronous Transfer ModeAsynchronous Transfer Mode (ATM) is a switching technique for telecommunication networks. It uses asynchronous time-division multiplexing, and it encodes data into small, fixed-sized cells. This differs from networks such as the Internet or Ethernet LANs that use variable sized packets or frames. ATM provides data link layer services that run over OSI Layer 1 physical links. ATM has functional similarity with both circuit switched networking and small packet switched networking. This makes it a good choice for a network that must handle both traditional high-throughput data traffic (e.g., file transfers), and real-time, low-latency content such as voice and video. ATM uses a connection-oriented model in which a virtual circuit must be established between two endpoints before the actual data exchange begins. ATM is a core protocol used over the SONET/SDH backbone of the Integrated Services Digital Network (ISDN).异步传输模式（ATM）是用于电信网络中的切换技术。它采用异步时分复用，并且它编码数据转换成小的，固定大小的细胞。这不同于网络，诸如使用可变大小的数据包或帧的因特网或以太网LAN。 ATM机提供了运行在OSI的第一层物理链路的数据链路层的服务。自动柜员机有功能的相似性与电路交换网络和小分组交换网络。这使得它对于必须同时处理传统的高吞吐量的数据流（如文件传输），以及实时，低延迟的内容，如语音和视频网络的好选择。 ATM使用其中一个虚电路必须在两个端点之间建立实际的数据交换开始之前，面向连接的模式。 ATM是使用过综合业务数字网（ISDN）的SONET / SDH骨干网核心协议。Consider a speech signal reduced to packets, and forced to share a link with bursty data traffic (traffic with some large data packets). No matter how small the speech packets could be made, they would always encounter full-size data packets, and under normal queuing conditions, might experience maximum queuing delays. That is why all packets, or cells, should have the same small size. In addition the fixed cell structure means that ATM can be readily switched by hardware without the inherent delays introduced by software switched and routed frames.考虑语音信号还原成数据包，并被迫（与一些大的数据包流量）分享与突发数据流量的链接。不管多么小的语音数据包可以做，他们总是遇到全尺寸的数据包，正常排队的条件下，可能会遇到的最大排队延迟。这就是为什么所有的数据包，或“细胞”应该具有相同的小尺寸。除了固定的细胞结构意味着ATM可以容易地通过硬件开关没有通过软件引入的固有延迟交换和路由帧。Thus, the designers of ATM utilized s