Southbound Interface

What Does Southbound Interface Mean?

A southbound interface (SBI) is a component’s lower level interface layer. It is directly connected to that lower layer’s northbound interface. It breaks down the concepts into smaller technical details that are specifically geared toward a lower layer component within the architecture.


In software-defined networking (SDN), the southbound interface serves as the OpenFlow or alternative protocol specification. It allows a network component to communicate with a lower level component.

Techopedia Explains Southbound Interface

The main objective of a southbound interface is to provide communication and management between the network’s SDN controller, nodes, physical/virtual switches and routers. It allows the router to discover the network topology, define network flow and implement several requests relayed from northbound application programming interfaces (API).

The management of network nodes is handled by the Network Management System (NMS) allowed by the southbound interface. The southbound integration is supported by the following interfaces:

  • Simple Network Management Protocol (SNMP)

  • Command Line Interface (CLI)

  • File Transfer Protocol (FTP) or SSH File Transfer Protocol (SFTP)

  • Telnet (TN) or Secure Shell (SSH)


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Margaret Rouse

Margaret Rouse is an award-winning technical writer and teacher known for her ability to explain complex technical subjects to a non-technical, business audience. Over the past twenty years her explanations have appeared on TechTarget websites and she's been cited as an authority in articles by the New York Times, Time Magazine, USA Today, ZDNet, PC Magazine and Discovery Magazine.Margaret's idea of a fun day is helping IT and business professionals learn to speak each other’s highly specialized languages. If you have a suggestion for a new definition or how to improve a technical explanation, please email Margaret or contact her…