混合軟體定義網路為由傳統網路到完全的軟體定義網路中的過渡時期，由於混合軟體定義網路可以比傳統網路獲得更大的效益，我們可以佈置部分的SDN交換機來增進當前的傳統網路。所以在有限的預算底下，我們需要一個有效的策略來佈署SDN交換機。換句話說，我們將尋求一個最佳佈署策略，將現有的傳統交換機部分提升至SDN的交換機。在此論文中，我們制定了四個覆蓋優化問題，包含 (1)給定成本下的最大化軟體定義網路路徑覆蓋率; (2)給定成本下的最大化軟體定義網路節點覆蓋率; (3)給定軟體定義網路路徑覆蓋率下的成本最小化; 及 (4)給定軟體定義網路節點覆蓋率下的成本最小化，並證明此四問題為NP-Hard問題。接著提出一個兩段式貪婪演算法來決定最合適交換機部署策略，經由模擬，我們的算法在覆蓋比率和部署成本皆有很好的效能。

Hybrid Software-Defined Networking (Hybrid SDN) is a transitional networking from traditional networking to pure SDN. Due to Hybrid SDN can gain greater benefit than traditional networking, we can deploy the SDN switches partially in legacy networks to enhance the performance of current networking. However, we need a good strategy to maximize the SDN-switch coverage under limited budget. In this paper, we formulate four coverage optimization problems, including (1) maximum the SDN path coverage under a given cost; (2) maximum the SDN hop coverage under a given cost; (3) minimum cost under given a SDN path coverage; and (4) minimum cost under a given SDN hop coverage; First, we prove that the four coverage optimization problems are NP-Hard problems. Then, we propose a Two-Step greedy algorithm to solve the SDN-switch deployment problems. The simulation results show that our algorithm gets a better performance than the previous work in terms of coverage ratio and deployment cost.

Abstract IV
List of Contents V
List of Figures VII
List of Tables VIII
I. Introduction 1
II. Related Work 4
III. Algorithm 8
3.1. Problem Formulation 8
3.2. Hardness Analysis 12
3.3. Two-Step (TS) Algorithm 14
A. Contribution Computation (CC) Procedure 15
B. Maximum Coverage (MaxCov) Procedure 19
C. Minimum Cost (MinCost) Procedure 21
3.4. Time Complexity Analysis 28
IV. Performance Evaluation 29
4.1. Simulation Environment 29
4.2. SDN Path Coverage Performance 30
4.3. SDN Hop Coverage Performance 35
V. Conclusion 41
Reference 42

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