寬頻交換機之排程與暫存管理的硬體設計研究

Abstract

近年來網際網路的技術與應用以著極快的速度在進行發展，無論是骨幹網路（Backbone）的頻寬或是用戶端設備的接取速度，都有大幅度的成長；不過隨著頻寬的增加，各種耗費頻寬的應用也跟著出現，夾帶著巨大的訊務量往返於網路連線之上，當頻寬不敷使用時，網路便會產生壅塞的情況，造成整體服務品質的下降；除此之外，不合法的使用者也會因為使用過多的頻寬而影響其他人的服務品質，因此合理的頻寬分配便成為一項重要的議題，這對於位處網路樞紐位置的節點例如交換機或路由器更是重要，因為他們的訊務量往往是整個網路當中最大的，壅塞通常在此產生。 本論文即著眼於此，以硬體實作為考量，並參考現存的排程演算架構去加以改進，希望能有效率地設計出寬頻交換機內部的排程器，擔任頻寬分配的工作；此外，封包暫存區的管理對於交換機而言也是一個相當重要的議題，暫存管理架構的好壞將對系統的效能產生很大的影響；而我們的演算架構除了能進行封包的排序處理外，也能同時解決暫存管理的問題。

The technique and application of the Internet develops rapidly in resent years. Both the backbone of the network and the user access devices have great advance in bandwidth and speed. As the bandwidth increases, many kinds of application demanding for a large amount of bandwidth appear. They bring huge amount of data to traverse in the network. Congestion occurs when the bandwidth is exhausted and the quality of service degrades at the same time. Besides, greedy users also affect the quality of others by sending too much data. Thus allocating bandwidth between users fairly becomes a very important issue. This is especially important for switches and routers in the backbone because they receive most of the data users transmit, congestion often occurs there. We hope to design the scheduling component inside a broadband switch efficiently. We will reference the existing algorithms and mention a new approach for ease of implementation by hardware. The scheduling component will allocate the bandwidth for our system. Buffer management is also important for a switch, it dominates the system performance. Our algorithm and design will provide a total solution for both the scheduling and buffer management problem.