In ATM, cells serve as universal units for all information types: data, voice, video, etc. Since switches know beforehand the size and format of each information unit sent through the network, switch architectures can be   (1)  . Furthermore, since the CMS determines the connection path during connection setup, switches do not have to make complex routing decisions on a   (2)   basis. Communication paths can be “hard wired” into the switch’s circuits to enable fast, simple decisions. Hardware techniques, using VLSI based state machines and in the future, optical switching techniques, can be applied to switches. Hardware Based switch matrices take advantage of all these   (3)   characteristics. The matrix approach to implementing cell switching greatly increases the scalability of ATM based solutions. One fundamental advantage of matrix based switches is that, as more ports are added to the switching complex, the aggregate switching capacity of the switch increases. In other words,  as  (4)  are added to a switched network, they tap into an increasing band width pool-the complete opposite of shared media networks, where user are forced to share smaller and smaller slices of a fixed amount of  (5)  .Simply put, cell switching based on ATM enables extremely fast, massively scalable networks. 

 (1) A.optimized    B.increased       C.decreased    D.fixed

 (2) A.cell by cell   B.object oriented   C.bit-by-bit    D.LAN

 (3) A.VLSI       B.OSI            C.CMS       D.ATM

 (4) A.cells        B.switches        C.users       D.approaches

 (5) A.data        B.media          C.bandwidth   D.information #p#

答案：

1、A   2、A   3、D   4、C   5、C

参考译文：

在ATM中，信元作为普遍使用的信息传输类型：数据，语音，视频等，因为事先知道每一个信息单位通过网络传送电平的大小和格式，因此交换机制可被优化，此外，由于CMS决定了期间的链接路径，交换机就不需要作出复杂的路由决定每个信元的交换。通信路径可以用“硬有线电路”链接到到交换电路更加快速、简单。采用超大规模集成电路为基础的硬件技术在未来，可应用于基于交换矩阵。基于交换阵列的硬件充分利用这些特性，大大提高了信元交换的可扩展性。基于ATM方案，其中一个根本优势为基础的矩阵交换机是，随着越来越多的端口添加到开关复杂，总交换容量的交换机增加。换句话说，当用户被添加到一个交换网络，他们进入了越来越宽度成完全相反的共享媒体网络，在那里用户被迫份额小片的一个固定数额的带宽。简单提出，基于ATM的信元交换能够非常快速并且大规模的扩展网络。