<Table> <Tr> <Td> </Td> <Td> This article needs additional citations for verification . Please help improve this article by adding citations to reliable sources . Unsourced material may be challenged and removed . (November 2014) (Learn how and when to remove this template message) </Td> </Tr> </Table> <Tr> <Td> </Td> <Td> This article needs additional citations for verification . Please help improve this article by adding citations to reliable sources . Unsourced material may be challenged and removed . (November 2014) (Learn how and when to remove this template message) </Td> </Tr> <P> Software - defined networking (SDN) technology is a novel approach to cloud computing that facilitates network management and enables programmatically efficient network configuration in order to improve network performance and monitoring . SDN is meant to address the fact that the static architecture of traditional networks is decentralized and complex while current networks require more flexibility and easy troubleshooting . SDN suggests to centralize network intelligence in one network component by disassociating the forwarding process of network packets (Data Plane) from the routing process (Control plane). The control plane consists of one or more controllers which are considered as the brain of SDN network where the whole intelligence is incorporated . However, the intelligence centralization has its own drawbacks when it comes to security, scalability and elasticity and this is the main issue of SDN . </P> <P> SDN was commonly associated with the OpenFlow protocol (for remote communication with network plane elements for the purpose of determining the path of network packets across network switches) since the latter's emergence in 2011 . Since 2012, however, for many companies OpenFlow is no longer an exclusive solution, they added proprietary techniques . These include Cisco Systems' Open Network Environment and Nicira's network virtualization platform . </P>

What is the purpose of an sdn controller
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