在多網域的軟體定義網路（SDN）環境中，每一個控制器皆需要經常地做訊息交換的動作， 而在現實環境中，網路中可能存在著一些錯誤的元件而導致正常的控制器無法獲得正確的訊息進 而發生系統錯誤。因此，為了改為上述的問題，本論文提出了一個較健全的控制器協議機制。透 過協議機制的運作，可讓系統中所有正常的控制器可以有效地獲得一個共同的分數值，進而透過 此值來維持系統的正常運作。除此之外， 允許網路中之故障控制器數量上限為(n -1)/3的條件 下，此n個控制器的系統可利用O(n2) 的時間複雜度及使用O(n2)的空間複雜度即可得到上述的正 確共同分數值。

In multi-domain SDN environments, the controllers need to exchange information frequently. In real situation, there may have some faulty controllers. Besides, the connection between controllers may be disturbed. All this faulty components may cause that fault -free controllers getting the wrong information, and the network cannot work well. Hence, in this paper, a robust controllers’ negotiation mechanism has been proposed. Based on the mechanism, all fault -free controllers can efficiently and robustly to get a common score about the information which are needed to b e shared by at most three rounds of score exchange phases. Moreover, when there are at most (n-1)/3 allowable faulty controllers, the time complexity and the space complexity of generating the correct score are O( n2) and O(n2) respectively, where n presents the number of total controllers.