The Software Defined Network (SDN) provides an
innovative paradigm for networking, which improve the
programmability and flexibility of the network. Due to the
separation between the control and data plane, all the control
logic transfer to the controller. In SDN, the controller, which
provides a global view of the whole network. That is why it acts as
the “Network Brain” of the network. Because the controller has
the capability to configure or reconfigure the forwarding devices
by customizing their policies in a dynamic manner. Thus, the
controller provides a centralized logical view of the entire
network. Therefore, all manipulation and implementation in the
network are control by the single controller in the SDN, which
increases the maximum chance of a single point of failure
(SPOF) in the network. As a consequence, it collapses the entire
network. Therefore, a fault tolerance mechanism is required
which reduce single point of failure in the network by using
multiple controllers. As a significance, this mechanism also
increases the scalability, reliability, and high availability of
services in the network. The three different roles of multiple
controllers are equal, master and slave exist in the SDN. In the
simulation, the Ryu SDN controller and Mininet tool are utilized.
During the simulation to analysis, what is happen when a single
point of failure (SPOF) occur in the network and how to use the
different roles of the multiple controllers (such as equal, master
and slave) which reduces the threat of single point of failure in
SDN network.