The Power of Programmable Network

SDN and SD-WAN have quickly become the industry buzzwords. To recap, SDN generally focuses on the Enterprise Data Centers and SD-WAN focuses on the Enterprise Wide Area Networks (WAN). While there are many benefits of using SDx, the foundational benefit of using these technologies is to make the enterprise networks programmable.

In this article, I will highlight how the enterprise networks have transformed from having distributed intelligence and control with some level of coordinated intelligence (ex. using routing protocols) to a completely programmable network with central intelligence and control.

Network Programmability - Traditional networks are designed based on the concept of distributed network intelligence with the ability to tweak the intelligence/outcome by changing the supported network parameters. In most cases, this requires making changes using vendor proprietary CLI interface on each individual device. This creates a challenge when you need to change the configuration on multiple devices, as is often the case in such networks. You not only have to tweak the parameters on multiple devices in your network, but also understand its impact on the overall network intelligence and performance (e.g. tweaking routing protocol metrics).

Network administrators at large enterprises have long felt the need to have a programmable network and they generally overcome this challenge by using expensive network orchestrator tools and scripting. However, the network administrators in Small and Medium enterprises (SMB) don't have the luxury of buying expensive network orchestration tools or have the resources to learn proprietary programming language(s) to use such tools. Consequently, a majority of large enterprises manage to emulate some level of programmability in their traditional network while the SMB enterprises, in many cases, can't afford to do the same.

Most SD-WAN products are cost-effective and have native support for enhanced programmability using industry standard RESTful API. These APIs are designed to be easily used by anyone with basic knowledge of a standard programming language like Python or Java Script. SD-WAN products also have native support for central intelligence and control that significantly increases the type of data driven real-time intelligent decisions you can trigger throughout the network using these API. This not only significantly improves the network programmability for large enterprises but also levels the playing field by extending the full benefits of network programmability to the SMB enterprises.

There are multiple benefits of using a programmable network. The most common use-case of leveraging the power of programmable network and RESTful APIs is to manage and control how much traffic, and under what network conditions, is sent over a usage-based expensive circuit like wireless LTE/5G when a corporate location has two or more network connections.

A traditional network using routing can handle the above scenario very well for a network blackout (circuit up/down) condition. But, its ability to handle the network brownout (partial outage or low performance) condition is heavily dependent on the capabilities of the routing protocol being used and the ability of the enterprise to handle complex configuration.

In a programmable network like SD-WAN, there are a lot of available options to handle both blackout and brownout conditions. For example, one of our SD-WAN clients uses the RESTful API to enable and disable the use of an expensive wireless link to augment the site bandwidth in real-time based on the number of active unique network users at the site. This enables the client to manage costs while at the same time provide high capacity and redundant network to its users when needed. A traditional routing based network will not be able handle such requirements without a lot of cost, complexity and customization because they are limited by the route manipulation metrics available in the routing protocol. With programmable networks like SD-WAN and SDN, there are endless ways in which you can do traffic steering and traffic engineering based on your business requirements. This is the power of having a programmable network!

Network Affordability - The devices in the traditional networks are generally oversized from the hardware perspective because each individual device could actively participate in making intelligent and complex decisions e.g. routing protocols, route convergence etc. Therefore, each hardware has to be powerful enough to handle this as well as data forwarding in real-time. This often results in over sized hardware and higher hardware price. Also, there is an upward pressure on the hardware price because such devices are generally proprietary and are only sold by one vendor.

A programmable network like SD-WAN generally overcomes this inefficiency by using standard x86 type hardware with Intel DPDK technology that is available from multiple manufacturers. SD-WAN also reduces some of the compute overhead on the devices by centralizing most of the network intelligence and control functions. SD-WAN devices focus most of their compute resources to do packet forwarding, encryption, and to send telemetry data to the central controllers. The controller has full visibility of the end-to-end path from the source all the way to the destination and can in real-time analyze the traffic and instruct the edge devices on the best way to handle the traffic based on the defined application policies.

Network Skill Set - The skill set needed to manage the network has changed from having to memorize product specific CLI commands to having a working knowledge of a standard programmable language such as Python or Java Script. Today, with programmable networks such as SD-WAN, having a fundamental understanding of networks and some basic knowledge of any standard programmable knowledge is much more important than having a network vendor specific certification that focuses on the use of their CLI.

No wonder that majority of the telecommunications companies globally have invested a lot of money over the last few years in retraining their technical staff with programming skills. Today's network administrators and managers need to know the basics of programming languages to provide the level of network functionality and automation expected by the business.

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