縱橫式非同步傳輸模式交換機的設計與製作

Abstract

有關ATM交換機的設計相當多，但是實際製作的卻很少。最主要的原因在 於硬體的設計與製作，不旦耗時費日且所費不貲。然而理論必須與實際結 合。故發展一套能快速實現設計的實作方法,是非常重要的。本論文的目 的便在於測試 "以硬體描述語言(HDL)結合場效可程式閘陣列(FPGA)的設 計方法，進行ATM交換機的設計與製作"的可行性與複雜度。本交換機使用 縱橫式(Crossbar)的交換結構，以輸入端佇列暫時貯存封胞，採用循環( Round Robin)排序的方法，做為競爭解析機制的演算法。首先，輸入埠必 須偵測是否有封胞要交換，吾人提出二種方法達成。其次，輸入埠自ATM 封胞標頭中取出交換所需的路徑資訊，交給交換控制電路。此路徑資訊包 括一路徑需求碼(Routing ID)和一位元的優先權位元。交換控制電路以此 資訊提供交換結構"交換圖樣"。最後，交換結構進行封胞交換。本論文採 用VHDL程式語言撰寫行為模組，然後以Synopsys公司所提供的高階設計自 動化軟體(包括邏輯合成器(Synthesizer)和模擬器(Simulator))完成高階 設計。接著以Xilinx公司所提供的轉換程式，將電路列表轉換成XILINX FPGA 晶片所需的位元流。最後以邏輯分析儀和CPU模擬器輔助，完成電路 的製作。在經過將近二年的實驗後，完成一2乘2的ATM交換機，驗證此設 計方式確實適合ATM交換機的設計與實作。 Although there are many designs of ATM switch proposed, only few of them have been implemented. The main reason is that hardware implementation takes a lot of time and costs much. However, any idea must be put into practice. So, it is very important to develop a method to implement the design easily. The purpose of this paper is to test the feasibility and complexity of a methodology for the development of an integrated circuit, which combines the new design method "Hardware Description Language"(HDL) and the new chip implementation product "Field Programmable Gate Array"(FPGA) to design and implement an ATM switch. This ATM switch uses Crossbar as the switching fabric. The cells are buffered at input temporarily, and the output contention problem is solved by "Round Robin" mechanism. First , the input ports examine whether there are cells to be switched. We propose two ways to do the examination. Second, from the header of each cell, the input port gets the routing information for switch control circuit. This routing information includes a routing ID and a priority bit. Then the switch control circuit used this information to provide switching fabric the "switch pattern". Finally, the switching fabric switches the cells. This thesis uses the VHDL programing language to describe the behavior of each module, then uses the high level automatic design software, including the Synthesizer and the Simulator, surpported by SYNOPSYS company to finish the high level design. The translation programs surpported by XILINX company then translate the netlist to the bitstream for the use of XILINX FPGA chip. Finally, using the logic analyzer and in-circuit emulator to help the implementation of the circuit. After two year's study, a complete 2 by 2 ATM switch circuit has been done. So, we can say that the new IC design method is applicable for the design and implementation of ATM switch.