New to Software-Defined Networks.

I know that an SDN involves an Application plane, a control plane and infrastructure plane. By definition, I know that the application plane is in the Application Layer and the Infrastructure layer is in the Network Layer. However, I do not have clarity on the control plane.

The control plane is responsible for the virtualization of the infrastructure layer. What layer of the TCP/IP model would the control plane fall in then?

1 Answer 1


OSI layers can be applied to network protocols (more or less) but not practically to SDN components.

The control plane is where the forwarding rules are defined and distributed to the forwarding plane components. Forwarding logic can take attributes from any OSI layer to make each forwarding decision - based on (with examples) link-layer protocol (Ethernet), its source or destination address (MAC), network-layer protocol (IPv4, IPv6), its source address or destination address (IP), transport-layer protocol (TCP, UDP, ...), its source or destination port, application layer details (HTTP URL parameters), and so on.

So basically the control plane lives in all OSI layers as does the forwarding plane. One of the points of SDN is to do all forwarding decisions in one step instead of distributing the process across several components (switches, routers, NAT routers, firewalls, load balancers, ...).

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