FAULT TOLERANCE MECHANISMS IN SOFTWARE DEFINED NETWORKS
A fault tolerance is an essential to ensure that the service of the network is continuous against the traffic failure. The two different type of network traffic available in the SDN are data traffic and control traffic. The data traffic exists in the data plane and the control traffic occur between the control and data plane. A link failure is a main reason for the data plane unavailable. To address this issue, the failover mechanism is used to select the other path to continuous the traffic in the plane when a link failure occurs. With the emergence of SDN/OpenFlow offer more flexible failover mechanism. Two different types of mechanisms are used restoration and protection. The restoration mechanism is used in the SDN when a link failure occurs, then switch can send the notification message regarding to the port status to the controller.