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

參考譯文：

在ATM中，信元作為普遍使用的信息傳輸類型：數(shù)據(jù)，語音，視頻等，因?yàn)槭孪戎烂恳粋€(gè)信息單位通過網(wǎng)絡(luò)傳送電平的大小和格式，因此交換機(jī)制可被優(yōu)化，此外，由于CMS決定了期間的鏈接路徑，交換機(jī)就不需要作出復(fù)雜的路由決定每個(gè)信元的交換。通信路徑可以用“硬有線電路”鏈接到到交換電路更加快速、簡(jiǎn)單。采用超大規(guī)模集成電路為基礎(chǔ)的硬件技術(shù)在未來，可應(yīng)用于基于交換矩陣。基于交換陣列的硬件充分利用這些特性，大大提高了信元交換的可擴(kuò)展性。基于ATM方案，其中一個(gè)根本優(yōu)勢(shì)為基礎(chǔ)的矩陣交換機(jī)是，隨著越來越多的端口添加到開關(guān)復(fù)雜，總交換容量的交換機(jī)增加。換句話說，當(dāng)用戶被添加到一個(gè)交換網(wǎng)絡(luò)，他們進(jìn)入了越來越寬度成完全相反的共享媒體網(wǎng)絡(luò)，在那里用戶被迫份額小片的一個(gè)固定數(shù)額的帶寬。簡(jiǎn)單提出，基于ATM的信元交換能夠非常快速并且大規(guī)模的擴(kuò)展網(wǎng)絡(luò)。