Multi Tenant data centers being used to provide cloud services has led to a number of network requirements that are difficult to meet using VRF, Q-In-Q or other tunneling techniques.A Cloud data center customer needs to be able to provision network resources such as virtual switches and RFC 1918 IP addresses without needing to consider similar resources being used by other tenants. Software Defined networking seeks to provide an END-to-END virtual network that consists of virtual forwarding tables ,virtual routers,virtual switches and controllers. Software Defined Networking can be used to create logical networks that consist of virtual network gear. SDN tracks the state of the underlying physical data center network along with the overlaying virtual networks.
State changes are recorded and the Physical or Logical components affected by these said state changes are configured to have their settings and operations updated to support the changes made by the data center’s customer. Software defined networking’s ability to provide distributed,rule driven control of large physical network elements presents a new way of virtualizing network resources.