SDN Networking - Software Defined Networking

    In the modern world, the business in the field of information technology makes ever greater demands on the flexibility and scalability of computer networks. So, an AOL IT market old-timer needed 9 years to attract one million customers, Facebook took 9 months, and DrawSomething online service took only 9 days.

    With all this, it can be observed that the main trends in the development of corporate networks and data center networks are:
    • the rapid growth of traffic volumes and a change in its structure towards the transmission of video and unified communications (UC-C);
    • the need to support mobile users (BYOD) and social networks;
    • high-performance clusters for processing Big Data (BIG DATA);
    • virtualization to provide cloud services (Cloud Bursting).

    At the same time, the network in its classical form (control via the command line and configuration files) becomes a limiting factor in the development of computing infrastructure. Classical approaches to solving problems, for example, based on network virtualization (VLAN, VRF), do not correspond to the level of development of server virtualization and storage systems. Traditional networks are primarily static and do not correspond to the fast dynamics of the development of modern IT business. Scaling capabilities of traditional networks do not meet the requirements of large businesses and service providers (Deutsche Telekom, Facebook, Google, Microsoft, Verizon and Yahoo), and distributed device management of traditional networks is too complex and inefficient. Binding to the selected network manufacturer does not guarantee support for future applications and services, so, according to rumors, Amazon’s next network upgrade was priced at nine zeros. As a result, there is a picture that traditional network architectures / designs become ineffective in dynamic environments.

    A new technology or approach to building information networks is needed to solve the above problems. This technology is and is called - Software Defined Networking or abbreviated SDN.

    What is an SDN?

    By definition from Wikipedia:
    Software-defined Networking (SDN from the English Software-defined Networking, also software-defined network) is a data transmission network in which the network control layer is separated from data transmission devices and is implemented programmatically, one form of computing resource virtualization .

    Let's decipher this definition. If we consider a modern network device (a router or a switch, it doesn’t matter), then it, like a pie, logically consists of three components.
    1. The management level is the CLI, embedded web server or API, and management protocols. The objective of this level is to ensure device controllability.
    2. The level of traffic control - these are various algorithms and the function of which is to automatically respond to traffic changes, that is, the intelligence of the device.
    3. Traffic transfer - functionality providing physical data transfer, the level of microcircuits and network packets.

    Figure 1 Typical network device

    What if:
    • centralize traffic management by separating management from devices?
    • centralize device management?

    As a result, the “new” router or switch serves only the data stream (DATAPLANE traffic transmission level), becoming simpler and cheaper, respectively. Of course, to completely deprive the network device of intelligence does not work, but it is enough to replace it with a simple forwarding table.

    All intelligence (MANAGEMENT PLANE and CONTROL PLANE) is transferred to a separate central device called the SDN controller.

    Figure 2 The logical model of SDN network devices

    So, we get:
    • Separation of traffic transfer functions from management functions (including control of both the traffic itself and the devices transmitting it)
    • A single, standard, open interface between control and transmission devices (called OpenFlow )

    • Centralized network management (SDN controller)
    • Virtualization of physical network resources
    • Programming capabilities of both equipment (OpenFlow) and applications (API - SDN controller)
    • Faster response to changes online
    • Optimize traffic flow (L2 / 3) through more backup paths
    • Easier and faster to configure networks
    • Significantly reduce application deployment time
    • Simplify network device management
    • Reduce network management costs
    • Centralized policy enforcement, increased performance, reduced latency leads to more effective interaction of users and applications both in corporate networks and in data center networks
    • Easy to manage. Manage entire networks, not network devices
    • Open standards-based protocols will allow various network equipment manufacturers to interact with each other, while increasing customer choice and competition between vendors while reducing costs, accelerating innovation in both software and hardware.
    • The SDN controller supports an open programming interface (API), which allows you to program it from the outside, creating an environment for automation and control, as well as scale functionality for future applications.
    • An application can request directly specific network requirements
    • Visibility of all network traffic by a controller

    Figure 3 General SDN architecture

    As you can see from the architecture, in addition to the classical network management by direct commands of the system administrator to the controller, the SDN controller supports running network management applications on itself. What are these applications?

    Each SDN application, in fact, is a network optimization interface for a specific business application (for example, Microsoft Lynk) and its main role is to change the network in real time to the current needs of the program being served. In the case of Microsoft Lynk, this could be, for example, changing the QoS network between two telephone subscribers to deliver a real-time HD video call without delays or creating a VPN tunnel between two subscribers.

    Figure 4 SDN application for MS Lynk

    If we consider in more detail the information flows in the SDN architecture, you can notice two main areas of information exchange: the first is between SDN applications and the second is for managing physical network devices.

    Figure 5 Structure and components of the SDN

    The first stream is called the “North Bridge”, and the second “South Bridge”. The protocol based on the RESТ API acts as the “north bridge”, and the OpenFlow protocol has taken root as the “south bridge”.

    Figure 6 Control information flows of the SDN controller

    What is OpenFlow?

    Openflow - a standard protocol, is the main element of the SDN concept which provides the interaction of the controller with network devices. The controller is used to manage the flow tables of the switches, based on which a decision is made to transfer the received packet to a specific port on the switch. Thus, direct network connections are formed in the network with minimal data transmission delays and the necessary parameters.

    Accordingly, the OpenFlow switch consists of at least two components:
    • flow table;
    • secure channel

    Figure 7 Example OpenFlow flow table

    Switches with OpenFlow support are already available on the market, so in the portfolio of the leader in the development of the SDN concept - Hewlett-Packard company, more than 40 switch models support OpenFlow version 1.3, respectively, they are ready to act as "bricks" for building a real SDN network.

    In addition to switches, Hewlett-Packard offers several models of ready-made SDN controllers and provides several free SDN applications for specific business programs, for example, Microsoft Lync. HP also maintains an active SDN developer community (, where users can share their ideas, as well as the SDN App Store, where users can download various applications to the HP VAN SDN controller in just a few clicks.

    Hewlett-Packard’s interest in SDN technology is not accidental. It is believed that SDN will change the network in the same way that virtualization in the enterprise server systems market did in its time. Accordingly, the SDN for Hewlett-Packard is a strategic direction, because success in this direction can provide leadership in the market, for example, the success of such large players in the market of network services as Amazon and Google actively using SDN in their work.

    Hewlett-Packard also believes that SDN should be built on the basis of open standards so that anyone can participate in this. Such an open ecosystem will resume the process of innovation in network technology, which has stalled over the past two decades.

    Kiev, March 23-24, the HP course will take place - Cloud Computing Foundation (EXIN)
    Distribution of HP solutions in Ukraine , Georgia and Tajikistan
    Catalog of all solutions and services of the distributor MUK

    MUK-Service - all types of IT repair: warranty, non-warranty repair, sale of spare parts contract service

    Also popular now: