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Difference Between Data Plane Vs Control Plane

Most widely used words in SDN discussion and believe me once you know the difference, it is easy to move ahead on SD-WAN journey. 

Control Plane is all out the intelligence which governs where to send traffic. This traffic originated by the router and destined to the router. Control traffic includes management traffic, routing updates and configurations updates. In short, you can say this type of traffic is a kind of signal traffic. 

Data Plane forwards the actual user traffic across the network patch decided by control plane traffic. Data plane traffic originated by users destined to users or servers and passed through routers. This is also known as the forwarding plane. 

Why does it matter?
Next generation routing (SD-WAN) is the one that follows the basic SDN principles where we see clear separations of both the plane and control plane. That is missing in the traditional network and, therefore, it faces the scalability issues where we depended on the fat routers to process large network control and data processing requirement. 

Fig 1.1- Data Plane Vs Control Plane

What if, I separate the control and data plane and make control plane software-defined? This thought gave birth to SD-WAN where control plane processing is take-care by the controllers deployed in a central site or in the cloud. By offloading the control plane traffic by the controller:
  • Customers are not dependent on the costly routers with high CPU to process control traffic
  • Customer overcome the scale limit – as the software can support the huge processing based on the server it is hosted and if required can be easily upgraded 
  • Control plane disruption does not impact the data forwarding. Once the router has the known good state of the network, it will continue to forward traffic 

Yes, when you talk SD-WAN where control and data planes are separate require security measure for traffic between the routers and the controller. Ask your SD-WAN vender how traffic is secured between them – believe me, if it true SD-WAN solution they will be able to answer!