差別服務/多重協定標籤交換網路中服務平衡之服務品質選徑及轉送機制

Abstract

隨著科技的進步及網路服務的蓬勃發展，愈來愈多的網路使用者基於種種的理由及目的而要求網路服務業者提供服務品質保證之網路服務。不同等級的服務可依各人服務需求的不同而提供不同程度的品質保證。近年來，有很多不同型態的服務品質選徑機制已被提出，以期能在高速分封網路上提供服務品質保證的網路服務。然而，就作者所知，在這些現有的機制中，沒有一個機制在為某一特定話務流選擇傳遞路徑時，會考慮到網路上不同服務等級間之話務混合情形。在這篇論文中，我們先舉例並說明在網路上同一服務等級中之不同話務流因行經含有不同話務混合之路徑而產生服務待遇不公平之問題。進而，提出一個新的選徑及轉送機制，稱之”服務平衡之服務品質選徑及轉送機制”。這個新的機制在選擇路徑時，特別考慮了各個服務等級之話務混合情形。我們的模擬結果顥示這個新的機制確實能有效地改善前述同一服務等級中之不同話務流間服務待遇不公平的問題。最後，為了確保端對端的服務品質，我們針對這個新的機制提出了一個可行的延伸方案。

More and more network users are demanding QoS services for various reasons and objectives. Depending on the service requirements, different classes of service with different degrees of QoS guarantees may be required. In recent years, many QoS routing mechanism had been proposed for providing QoS services in high-speed packet networks. However, to the best of author’s knowledge, none of them take the traffic mixing states of traffic flows of various service classes into account for selecting a route for a particular QoS traffic flow. In this paper, we firstly present the potential unfairness problem among the traffic flows of the same service class traversing different paths with different states of traffic mixture. Then, we propose a new QoS routing and forwarding mechanism, called “Service Balanced QoS Routing and Forwarding” (SBQR) mechanism, which takes the traffic mixing states of links into account to determine a QoS path for a particular QoS flow. Simulation results show that this new mechanism does improve the unfairness problems of traffic flows belonging to the same service class. Lastly, an extension to SBQR (SBQR+) is proposed to provide a means to find a path with assured end-to-end delay performance for a QoS traffic flow.