Software Defined Networking

Overview

As we are aware that Ultimately, programmability of the network will be critical for business growth. The traditional methods of management device by device and system by system using manual methods simply cannot scale at the rate required today. 

Automation via network programmability (adopting a DevOps approach for the network) is one of the ways in which IT can combat the costs associated with rapid growth without burning out engineers.

This is why software-defined networking is not only good for the network, but for the business. With SDN, we’re making the network programmable. And when we take a deeper look at what it means to make the network programmable, we find that it involves both the control plane and the data plane and that both are valuable in containing costs and enabling business growth.

What is SDN?

Software-Defined Networking (SDN) is a network architecture approach that enables the network to be intelligently and centrally controlled, or ‘programmed,’ using software applications. This helps operators manage the entire network consistently and holistically, regardless of the underlying network technology.

The goal of Software-Defined Networking (SDN) is to enable cloud computing and network engineers and administrators to respond quickly to changing business requirements via a centralized control console. It helps organizations accelerate application deployment and delivery, dramatically reducing IT costs through policy-enabled work-flow automation. 

SDN encompasses multiple kinds of network technologies designed to make the network more flexible and agile to support the virtualized server and storage infrastructure of the modern data centre.

Software-defined networking originally defined an approach to designing, building, and managing networks that separates the network’s control or SDN network policy (brains) and forwarding (muscle) planes thus enabling the network control to become directly programmable and the underlying infrastructure to be abstracted for applications and network services for applications as SDN cloud computing or mobile networks.

The drive for network programmability naturally led to an embrace of open source networking initiatives at every layer of the networking stack. OpenDaylight is the by far the largest and most mature project in this new stack, and a core component of the new open networking ecosystem.

Benefits of SDN?

The benefits of such an approach of networks being programmable were obvious: no more arcane protocols to learn. No more waiting and hoping for networking vendors to develop specialized features you need. And if you could develop your own features, you could then optimize your device selection for price and performance independently of feature-richness.

By disaggregating the vertically integrated network device stack, and reimagining the control plane as a device-independent operating system, several longstanding goals can now be achieved:

  • Interoperability of different physical and virtual device types from different vendors.
  • Optimization of device selection–for price and performance independently of services features.
  • Continuous visibility of flows from source to destination.
  • Common management framework for all devices.
  • Programmability to shape network behaviour according to users’ needs.
  • Automation of and by policy.

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 SDN models 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.

The Software-Defined Networking Framework

Software-Defined Networking is Not OpenFlow, Often people point to OpenFlow as being synonymous with software-defined networking, but it is only a single element in the overall SDN architecture. OpenFlow is an open standard for a communications protocol that enables the control plane to interact with the forwarding plane. It must be noted that OpenFlow is not the only protocol available or in development for SDN.

Software Defined Networking Image

Software-Defined Networking Use Cases

As detailed above, Software-Defined Networking offers several benefits for businesses trying to move into a virtual environment. There is a multitude of use cases for different organizations, including carrier and service providers, cloud computing and data centres, as well as enterprise campuses.

For carrier and service providers, Software-Defined Networking offers bandwidth-on-demand, which gives controls on carrier links to request additional bandwidth when necessary, as well as WAN optimization and bandwidth calendaring. For cloud computing and data centres, network virtualization for multi-tenants is an important use case as it offers better utilization of resources and faster turnaround times for creating a segregated network. Enterprise campuses experience network access control and network monitoring when using Software-Defined Networking policies.

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