在下一代5G網路中，網路組件和服務被虛擬化並在虛擬機或容器中運行。此外，利用將網路服務運行在更接近終端用戶的邊緣雲來減少端對端延遲。但是，邊緣雲中的計算資源有限，因此為了最大限度地減少總體服務的延遲，必須仔細決定在邊緣雲中應該提供哪些服務。在本文中，我們提出了一個名為Service Cache（S-Cache）的新框架，它自動暫存邊緣雲中流行的服務。此外，我們設計了一個新的暫存替換策略，來最大化暫存命中率。在我們的評估中，我們使用來自Google的真實日誌文件並選擇這些文件形成兩個數據集來評估性能。將我們的暫存替換策略與Greedy-Dual-Size-Frequency（GDSF），Least-Frequently-Used（LFU）和其他暫存策略進行了比較。實驗結果表明，暫存命中率平均提高了39％，並且暫存替換策略的平均延遲在這兩個數據集中平均降低了41％和38％，因此我們的方法優於其他現有的暫存策略，更適用於Multi-access Edge Computing的環境中。在實作中，S-Cache依靠OpenStack將服務克隆到邊緣雲，並使用OpenFlow來引導網路流量。我們還評估了將服務克隆到邊緣雲的成本，此實驗是使用我們所提出的框架和不同真實的服務下所測量出來之克隆成本並討論了從實驗結果中得出的結果。

In next-generation 5G cellular networks, network components and services are virtualized and run either in virtual machines (VMs) or containers. Moreover, edge clouds (which are closer to end users) are leveraged to reduce end-to-end latency. However, the computational resources are limited in edge clouds. To minimize overall service latency, it is crucial to determine carefully which services should be provided in edge clouds. In this paper, we propose a novel framework named Service Cache (S-Cache), which automatically caches popular services in edge clouds. In addition, we design a new cache replacement policy to maximize the cache hit rates. Our evaluation used real log files from Google to form two datasets to evaluate the performance. The proposed cache replacement policy was compared with other policies such as greedy-dual-size-frequency (GDSF) and least-frequently-used (LFU). The experimental results show that the cache hit rates are improved by 39\% on average, and the average latency of our cache replacement policy decreases 41\% and 38\% on average in these two datasets. This indicate that our approach is superior to other existing cache policies and is more suitable in multi-access edge computing environments. In the implementation, S-Cache relies on OpenStack to clone the service to edge clouds and uses OpenFlow to direct network traffic. We also evaluate the cost of cloning the service to an edge cloud. The cloning cost of various real applications is studied by experiments under the presented framework and different physical environments.

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