SDN - 10 years from idea to implementations

    For any technology, and even more so in the IT field, 10 years is a sufficiently noticeable period for it to be possible, on the one hand, to assess penetration and impact on the infrastructure, and on the other hand, to assess and predict future prospects. So, SDN - Software Defined Network - a software-defined network, has it become a panacea, a “unicorn” or a soap bubble in the telecommunications structure?

    This concept was first voiced at the 15th Usenix Security Symposium in Vancouver in August 2006 as part of the SANE: A Protection Architecture for Enterprise Networks report., and, strangely enough, this report was focused on the security of this network solution, since SANE used "a very conservative method of ensuring security - all rights and access to the network were determined only by a single central domain controller." This report brought together three university schools - Stanford, Berkeley and Carnegie Mellon, however, Nicira, which was the first to implement SDN-based projects, included representatives of only Stanford and Berkeley, where in 2008 the first SDN-based network was deployed on campuses.

    What is the difference between this network concept and the usual IDN - Infrastructure Defined Networks?

    SDN has three levels

    • infrastructure level, providing a set of network devices (switches and data transmission channels);
    • a management level that includes a network operating system that provides applications with network services and a software interface for managing network devices and a network;
    • Network application layer for flexible and efficient network management.




    It is the separation of these three obvious levels and the creation of standards for control and data transfer that actually is the SDN. There was a small revolution, and from the world where iron producers ruled with their OS at the router level, a new world appeared, where they were offered new rules for doing business, new standards.

    Currently, the main actively developing and supported organization of the Open Networks Foundation, the standard for SDN, is OpenFlow, an open standard that describes the requirements for a switch that supports the OpenFlow protocol for remote control.

    With the help of existing routers, two main tasks are usually solved: forwarding - forwarding a packet from an input port to a specific output port, and data management - processing a packet and deciding where to forward it based on the current state of the router.

    The development of routers still went along the path of convergence of these levels, however, with a focus on transmission (hardware acceleration, software improvement and the introduction of new features to increase the speed of decision-making on the routing of each packet), while the control level remained fairly primitive and relied on complex distributed routing algorithms and intricate instructions for configuring and configuring the network. Of course, the router software that implements the management level was proprietary and closed. Which led to our favorite technical certifications and vendor crusts at sky-high prices.

    In the OpenFlow standard, the controller interacts with the switch using the OpenFlow protocol - each switch must contain one or more flow tables, a group table and support the OpenFlow channel for communication with a remote controller - server. The specification does not regulate the architecture of the controller and the API for its applications.

    Thus, the SDN's voiced idea of ​​creating a unified, manufacturer-independent network equipment, software-controlled interface between the controller and the network transport medium was reflected in the OpenFlow protocol, which allows users to determine and control who with whom, under what conditions and with what quality interact on the web.

    As in the 2006 report, the key element is the controller - although, if it had previously been “occupied” with security issues, now its functions have become wider - it is a separate physical server that can manage one or several OpenFlow switches and contains a network an operating system that provides network services for low-level management of the network, network segments and the state of network elements, as well as applications that provide high-level management of the network and data flows.

    Each controller has at least one application that manages the switches connected to this controller and generates an idea of ​​the topology of the physical network under the control of the controller, thereby centralizing management.

    This is all a boring and clever description, which leads to the fact that due to centralization, possible virtualization of networks and load management, practical results are measured in reducing operating costs due to a more complete use of existing resources. Moreover, the introduction and addition of functionality in the data center does not lead to a change in architecture, therefore, simplifies subsequent support. De facto SDN allows you to build scalable clouds for specific tasks, while still possessing great flexibility and "intelligence" when managing resources.

    But what about our heroes, who first appeared in Vancouver, and then created Nicira and were the first to implement a number of commercial projects? In mid-2012, this company, along with all the achievements, was bought for $ 1.26 billion by VMware, which led to a boom in purchases of such startups on the SDN market in 2012 - a total of about $ 1 billion was spent. At the moment, almost all the world's leading IT and telecom vendors support and offer certain solutions based on SDN, and, despite 10 years of history, this technology is still considered promising and has not shown everything that it is capable of building highly loaded and secure solutions . For the first five years, the concept of SDN has come a long way - from a small report to the first-born - pioneer companies that have been able to prove the benefits of the new network format.

    However, not everything was easy and simple, there were also difficulties - imagine what it is to play on a virtually monopolized market, undermining the primacy and supremacy of a universally recognized leader. Training of new specialists, the emergence of network architects of a different level, who will see the potential and structure of networks in a completely new way, visualize and implement with new introductory information. In addition, anyway, before making a profit due to savings and full network load, SDN requires investments, if not in hardware, then in design, calculation and implementation. It all took time, effort, a proper level of market understanding. About this, as well as about practical cases of implementation, we will write further in the following materials.

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