以超額允入法提升資源使用率


Improving Resource Utilization by Over-admission


黃國展

通訊網路使用網路聚合(Network Convergence)的策略,以此提供一個開放的服務平 台,ALL–IP網路,因ALL–IP網路是以封包交換網路承載各類服務[1],所以不容易保證 服務品質。一個經常被採用的方式是使用資源保留(Resource Reservation)方式以保證 服務品質,但服務可能會因失約或未依約沒有充分運用所保留之資源而導致資源閒置、降 低網路資源使用率。為了要提高資源使用率,營運者必須要有解決的方法,以提高整體資 源使用的效能。 本研究提出一個有效使用資源的概念–超額允入(Over-Admission),超額允入的意 義是讓允入控制機制允入比所擁有的資源量還要多的訊務量,以增加資源使用的效能。但 是超額允入訊務之後,Admission Controller可能會允入過多訊務造成溢流 (Overflow)。這會使系統效能下降,所以網路管理者必須要找出合適的允入量以提高系 統整體效能。 本研究建立分析模型係以供計算最佳允入量,並以模擬進行模型驗證與效能評估,經 由實驗結果可以驗證本分析模型相當準確而超額允入的確可以大幅提高資源使用率。

The telecommunication industry is moving toward a converged network, which uses a single global IP based packet-switched network, which uses a single global IP based packet-switched network to carry all types of network services, the quality of service cannot be fully guaranteed [1]. One of the popular methods to guarantee the quality of service is to use resource reservation. This kind of methods, however, might cause resource underutilization because the resource requesters may not show up or, even if does, it does not fully utilize the reserved resources. In order to enhance the efficiency of resource utilization, this study proposed an efficient resource utilization concept, that is, over-admission. Over-admission, in which the admission controller may admit more traffic volume than what it can allowed. Even though over-admission is effective, it has its own problems: the admission controller may admit too excessive traffic to impair the system performance. In order to maintain system performance, it is important for the network administrators to find out the appropriate admitted amount that does not cause excessive overflow. In this thesis, an analysis model is constructed to estimate the optimal admitted traffic amount under various traffic conditions. Then, simulation is conducted to verify this model and to evaluate the performance of our proposed method. The results reveal that this analysis model can improve the efficiency of resource utilization.