We have seen the traditional network architecture and the challenges faced by them. Let us now look at a typical SDN architecture and how it addresses these challenges.
The following diagram depicts a simplified SDN architecture where the control plane is centralized into a controller. It also considers OpenFlow as the protocol between the centralized control plane and the distributed data plane. While OpenFlow is the most popular SDN protocol between control and data plane, SDN platforms such as OpenContrail use XMPP and BGP as control plane protocols:
Figure 2: Simplified SDN-based network architecture.
In traditional networks, control plane was distributed and running on each networking device. The SDN model is to centralize the control plane. This centralized control plane is basically a software entity commonly referred to as the SDN controller. By centralizing the control plane, the interoperability problem is addressed to...