訊務塑型器-使用參數控制的深入研究與差異性服務網路新的量測機制

Abstract

在這篇論文中，我們更進一步探討在非同步傳輸模式網路更多變的環境下乏晰訊務塑型器(TS)-使用參數控制(UPC) 與類神輕乏晰訊務塑型器(TS)-使用參數控制(UPC) 的強健性。乏晰TS-UPC是由傳統漏水桶法與乏晰水增額控制器(FIC) 所構成的，FIC利用此連線的長期平均速率和短期平均速率來調整水增額的量。類神經乏晰TS-UPC是由傳統漏水桶法與類神經乏晰水增額控制器(NFIC)所構成的，同樣的NFIC也是採用此連線的長期平均速率和短期平均速率來決定水增額的量，而且它有一個額外的強制訊號(reinforcement signal)使的它有線上(on-line learning)學習的能力，可以更精確的反應訊務的情形。模擬結果顯示類神經乏晰TS-UPC與乏晰TS-UPC效能表現都優於傳統TS-UPC，而類神經乏晰TS-UPC又優於乏晰TS-UPC。 近來有人提出差異性服務(Differentiated Service)網路架構以提供不同程度的服務品質保證。在差異性服務網路架構下，位於邊緣路由器(edge router)的訊務調節器(traffic conditioner)負責監測進來的匯集訊務，並且根據監測結果來給予訊務相對應的處理。量測器(meter)是訊務調節器重要的一部分，它是用來量測進來的匯集訊務，以確保匯集訊務不會超過訊務合約。量測器和使用參數控制器扮演相同的角色，但不同的是量測器是對匯集訊務作監控的。在這篇論文中，我們提出增強型的雙速率三色標記器(TRTCM)與增強型的時間滑動視窗三色標記器(TSWTCM)，它們均可保護高優先權的封包不受低優先權的封包的影響，以及當有足夠的資源時允許提高封包的優先權藉以改善頻寬的使用效率。增強型的TRTCM是由兩個圖騰桶法(token bucket)所構成的，而對於封包作標記則是由圖騰使用的情形以及進來的封包標記來決定。增強型的TSWTCM是由一個速率量測器(rate estimator)與一個標記器(marker)所構成的，速率量測器負責量測匯集訊務中不同優先權封包的速率，標記器根據量測的速率和最高速率(PTR)與協定速率(CTR)作比較後再決定對封包的標記。在模擬結果中，增強型的TRTCM效能表現和增強型的TSWTCM差不多，但是增強型的TRTCM和增強型的TSWTCM效能表現明顯優於TRTCM。

In this thesis, we further investigate the robustness of the fuzzy TS-UPC and the neural fuzzy TS-UPC under more variant environment in ATM networks. The fuzzy TS-UPC is composed of the conventional leaky bucket and the fuzzy increment controller (FIC). FIC is used to compute the appropriate increment value according to the long-term mean rate and the short-term mean rate. The neural fuzzy TS-UPC is composed of the conventional leaky bucket and the neural fuzzy increment controller (NFIC). NFIC is used to intelligently compute the increment value according to the long-term mean rate and the short-term mean rate. In NFIC, the reinforcement learning can learn on line from a reinforcement signal (the difference between desired loss ratio and measured loss ratio), so the increment value can reflect accurate traffic condition. Under the more variant environment, simulation results show that the neural fuzzy TS-UPC and the fuzzy TS-UPC both perform better than the conventional TS-UPC, and the neural fuzzy TS-UPC outperforms than other TS-UPCs. Recently the Differentiated Service (DiffServ) model has been proposed to provide different degrees of QoS guarantee. The traffic conditioner located in the edge router monitors the aggregate traffic of incoming packets and takes corresponding actions according to the monitoring results. One important component of the traffic conditioner is the meter. It is used to monitor the aggregate traffic of incoming packets to ensure that the aggregate traffic would not exceed negotiated traffic profile. It plays the same role as UPC, but the difference between the meter and UPC is that the meter works at the aggregate traffic. We propose the enhanced TRTCM (Two Rate Three Color Marker) and the enhanced TSWTCM (Time Sliding Window Three Color Marker) that not only protect high priority packets from affecting by low priority packets but also improve the utilization by allowing promotion of packets when there is available bandwidth. The enhanced TRTCM consists of two token buckets and decisions on marking of packets depend on the token usage of the two token buckets and the colors of incoming packets. The enhanced TSWTCM consists of a rate estimator and a marker. The rate estimator measures the incoming rates of different priority packets within a fixed window size, and the marker determines the marking of packets based on the measured rates as compared to the PTR (Peak Target Rate) and the CTR (Committed Target Rate). Simulation results show that both the enhanced TRTCM and the enhanced TSWTCM outperform the TRTCM.