An Introduction
What is SDN?

Software-defined networking (SDN) is an architecture that aims to make networks agile and flexible. The goal of SDN is to improve network control by enabling enterprises and service providers to respond quickly to changing business requirements.



How Does Software-Defined Networking Work?

Software-defined networking providers offer a wide selection of competing architectures, but at its most simple, the software-defined networking method centralizes control of the network by separating the control logic to off-device computer resources. All software-defined network solutions have some version of an SDN Controller, as well as southbound APIs and northbound APIs:

Controllers: The “brains” of the network, SDN Controllers offer a centralized view of the overall network, and enable network administrators to dictate to the underlying systems (like switches and routers) how the forwarding plane should handle network traffic.

Southbound APIs: Software-defined networking uses southbound APIs to relay information to the switches and routers “below.” OpenFlow, considered the first standard in SDN, was the original southbound API and remains as one of the most common protocols. Despite some considering OpenFlow and SDN to be one in the same, OpenFlow is merely one piece of the bigger landscape.

Northbound APIs: Software-Defined Networking uses northbound APIs to communicates with the applications and business logic “above.” These help network administrators to programmatically shape traffic and deploy services.



Benefits of SDN

SDN is widely using because of its benefits. Followings are the benefits of SDN-

 

• With SDN, an administrator can change any network switch's rules when necessary

 

• prioritizing, deprioritizing or even blocking specific types of packets with a granular level of control and security.

 

• It is especially helpful in a cloud computing multi-tenant architecture, because it enables the administrator to manage traffic loads in a flexible and more efficient manner.

 

• It enables the administrator to use less expensive commodity switches and have more control over network traffic flow than ever before.

 

• A network administrator need only deal with one centralized controller to distribute policies to the connected switches, instead of configuring multiple individual devices. This capability is also a security advantage because the controller can monitor traffic and deploy security policies. If the controller deems traffic suspicious, for example, it can reroute or drop the packets.

 

• SDN also virtualizes hardware and services that were previously carried out by dedicated hardware, resulting in the touted benefits of a reduced hardware footprint and lower operational costs.

 
Challenges with SDN

Security is both a benefit and a concern with SDN technology. The centralized SDN controller presents a single point of failure and, if targeted by an attacker, can prove detrimental to the network.

Conclusion

In general, SDN technology plays an important role in cloud computing multi-tenant architecture and helping networking admins to control both software and hardware.