隨著5G時代來臨，網路服務愈趨多樣化，各種服務對於網路資源的需求不盡相同，但都運行在同一實體網路中，如何靈活彈性地使用網路資源以滿足各種應用的不同需求是一項挑戰。為了達到上述目的，網路切片的概念被提出，其主要目標是將一個實體網路切成多個虛擬網路各自對應到不同的應用場景，虛擬網路之間邏輯獨立且各自提供不同的網路功能及資源。作為實現網路切片概念之主要技術，軟體定義網路及網路功能虛擬化在近年來的研究相當興盛。利用網路功能虛擬化技術，網路專用設備之軟體功能可以轉移至一般商用伺服器上並動態部署；在軟體定義網路架構下，控制層與資料層分離，邏輯集中的控制器將虛擬化的資源串接起來。
本論文基於軟體定義網路架構，設計一跨網域網路切片系統，透過中央編排向管理不同網域資源之控制器進行溝通和協調，分配承租戶所需之頻寬資源。在控制層方面，引進網路功能虛擬化技術，將控制層之功能分化並運行於容器中，使多台控制器協同運作執行承租戶之決策，在分散控制層的運算成本的同時，依據整體負載調整控制器之數量以更有效地使用資源。實驗結果顯示，經由本論文所設計之切片系統，承租戶內之終端設備所使用的頻寬和其延遲可達到承租戶之要求；藉由多控制器之負載平衡機制，控制器超載之情況將能減緩，同時搭配動態調整控制器數量之方法，達到有效利用運算資源的目的。

With the advent of 5G, the growing number of network services with different requirements poses challenges for network operators. In order to use network resources flexibly to meet various demands, the concept of network slicing was proposed. Its main goal is to cut a physical network into multiple virtual networks with different sizes and structures. The virtual networks are logically independent and each of them corresponds to different application scenarios. As the main enablers of network slicing, researches on Software-Defined Networking(SDN) and Network Function Virtualization(NFV) have become popular in recent years. With NFV, network functions can be abstracted from dedicated devices and deployed on standard servers dynamically. By adopting SDN architecture, the control plane can be separated from the data plane, and the SDN controller is responsible for concatenating virtualized functions and resources.
This thesis designed a cross-domain network slicing system in SDN environment. A core controller manages the resource in a domain, and the slice orchestrator negotiates with core controllers for cross-domain resource allocation. The functions in control plane are split and deployed in different SDN controllers in the format of containers. By introducing NFV, the slicing system can dynamically deploy multiple controllers that consuming much computing resource to execute decisions made by tenants. At the same time, this thesis proposed a load balancing mechanism that can migrate the load among controllers and adjust the number of controllers based on the current load of controllers. The results show that the slicing system can fulfill the bandwidth and delay requirements from tenants. For the load balancing mechanism, the results show that it can mitigate the overload condition of controllers.

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