In these recent years, Software Defined Network (SDN) is predicted to be the future network. The basic idea of SDN is data plane and control plane which are separated unlike traditional network that has both planes in one device. Therefore, the controller has key controlling functions of its SDN environment. Many researchers discuss where to place the controller in order to get the optimal delay. However, these researches only focus on switches that are connected to one controller. There are some advantage for switches to connect to more than one controller such as efficient load balance, fail-over and reliability. Thus, we will discuss the controller placement where switches can connect to multiple controllers. This is important to answer the controller locations in a topology and percentage of switch connecting to each controller distribution load from a transmission delay view. Therefore, we will calculate the percentage and location by Switch to Multiple Controller Placement (SMCP). The result shows that SMCP can reduce 20-30% of transmission delay compared to random placement.

In these recent years, Software Defined Network (SDN) is predicted to be the future network. The basic idea of SDN is data plane and control plane which are separated unlike traditional network that has both planes in one device. Therefore, the controller has key controlling functions of its SDN environment. Many researchers discuss where to place the controller in order to get the optimal delay. However, these researches only focus on switches that are connected to one controller. There are some advantage for switches to connect to more than one controller such as efficient load balance, fail-over and reliability. Thus, we will discuss the controller placement where switches can connect to multiple controllers. This is important to answer the controller locations in a topology and percentage of switch connecting to each controller distribution load from a transmission delay view. Therefore, we will calculate the percentage and location by Switch to Multiple Controller Placement (SMCP). The result shows that SMCP can reduce 20-30% of transmission delay compared to random placement.

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