隨著網際網路與雲端技術快速發展，網路服務供應商在有限的機房空間內，為了提供大量網路服務需求，必須增加更多專用硬體設備用以提供特定網路功能，且設備之間連接與設置亦是非常繁雜。因此，在未來網路下，傳統網路建置方式勢必無法因應大幅成長需求，故網路功能虛擬化(Network Function Virtualization, NFV)技術為一解決方式，NFV可將網路功能進行虛擬化，以軟體方式安置在虛擬化機器以提供網路功能，並結合服務功能鏈(Service Function Chaining, SFC)概念技術來導向所需的服務功能，達到可隨意地配置所需網路功能，降低網路管理人員於建置及管理網路環境之複雜度。
在一多服務節點(Service Nodes, SNs)的NFV環境中，建構有許多服務功能，面對資源有限的環境與不同的網路功能需求，本研究著重於分析與研究如何挑選應由哪些服務功能實例(Service Function Instances, SFIs)組合的服務功能路徑(Service Function Path, SFP)，進而避免系統的負載不平衡，且相對提供較高服務層級協議(Service Level Agreement, SLA)之服務鏈。因此，本研究致力於設計基於NFV之SFC整合架構與SFP選擇機制研發，來彈性地提供符合要求者所需網路服務功能之服務鏈。
本研究從兩個情境案例進行探討，採用本研究所提出的SFP選擇機制可提升環境資源利用率，分散環境中SFIs的負載避免負載過於不平衡，增加整體系統可服務的服務鏈要求數量，並降低封包遺失率。在採用本研究機制與沒有採用機制相比，於Case 1僅考慮負載的情況下，可提升資源利用率21.32%，降低30.02%的平均負載差異；於Case 2多加考量價格的情況下，可提升資源利用率10.31%，降低18.73%的平均負載差異。另外，從拒絕率可看出，採用本研究之機制提升了整體系統可服務的服務鏈要求數量，並降低平均封包遺失率1.91%。

With rapid development of Internet and cloud, network service providers must increase more dedicated hardware equipment to provide more network services in limited room space. Moreover, settings and connection between devices is also complicated. The traditional way of network construction cannot meet with demands of substantial growth. Network Function Virtualization (NFV) was proposed to solve above problems. NFV can provide network functions by way of placing them with software in virtual machines. And then NFV combined with Service Function Chaining (SFC) achieve guide flow to a required service functions. With this technology can be more arbitrary to configuration required network functions, and reduce complexity of construction and management of network.
In multiple Service Nodes (SNs) within NFV environment, there are a number of network functions are built. For resource-constrained and different network functional requirements. This study focuses on selection of Service Function Instances (SFIs), which are combined into Service Function Path (SFP). Thus avoiding unbalanced load in a network system and providing a service chain with higher service level agreement (SLA). Therefore, this study focuses on design of NFV-based SFC integration architecture and development of SFP Selection mechanism to flexibly provide service chain that satisfies service request.
This study discusses two situation cases. By using proposed SFP Selection mechanism can improve resource utilization of SFIs, avoid load of SFIs overloading, increase number of service chains that can be serviced by overall system, and reduce packet loss rate. Compare with using proposed mechanism and without using mechanism. Case 1 that only consider load of SFIs, SFC Controller with proposed SFP Selection mechanism can improve resource utilization rate by 21.32%, reduce average load difference by 30.02%. Case 2 that more consider situation of acceptable price, SFC Controller with proposed SFP Selection mechanism can improve resource utilization by 10.31%, and reduce average load difference by 18.73%. In addition, from analysis of rejection rate, proposed mechanism improves amount of service chains that can be serviced by whole system, and reduces average packet loss rate by 1.91%.

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