SDN network architecture: three layers and three interfaces

As we all know, SDN is a network with a separate control plane and forwarding plane. It has an open programmable interface that can centrally control the network, thereby realizing the automatic configuration of network services. Today, let's take a look at its network structure.

SDN Network Layer

SDN networks have three levels:

• Application layer: Firewall, NAT, QoS…
• Control layer: linking the upper and lower levels
• Forwarding layer: the device that specifically forwards traffic

Look at the beautiful pictures below:

Three levels of SDN

Three interfaces

For the three levels, the controller is the center, and there are three corresponding interfaces:

• Northbound interface
• Southbound interface
• East-West Interface

Three interfaces

Summarize

Many network names look grand, but they actually mean east, west, south, and north. When I first heard about the southbound interface, I was intimidated. I thought it was something very grand. But after knowing other contents, I felt it was a bit too simple!