The evolution of SDN: the way to a great programmable future

According to analysts, by 2018, global spending on software-configured networks that are of primary importance for cloud data centers will increase to $ 35 billion:

Cloud4Y analysts conducted a cycle of foresight and long-term strategic planning sessions, and today we want to share with you the image of the future we have achieved. This article focuses on the evolution of software-defined networks over the next decade, as well as their role for corporate communications, the Internet and wireless connections.

General trend

The first wave of cloud computing began with the centralization and virtualization of servers - as a result of a change in the approach to data storage and the use of software. The emerging second wave affects the development of software-defined networks ( SDN ), centralization and virtualization of network management in the cloud.

After SDN was established in data centers, SDN deployment expanded into NaaS (network as a service), a model offered to businesses and private customers.

What for? Like a fish needs a bicycle?

SDN reduces the need for technical specialists (forgive, Habr!) - and, as a result, reduces capital ( CapEx ) and operational ( OpEx ) costs. SDN also provides fast interaction between services, since the data is programmed by remote control services (controllers) and applications. Globally, SDN is transforming the network into a computational domain and is adopting more and more standardization practices applicable to computers and software.

Thus, we can identify software-defined networks (SDN) as one of the most significant paradigm shifts registered in the network industry in recent years.

Prehistory

The emergence of SDN and OpenFlow (data processing control protocol in SDN) was caused by the need to keep up with new network requirements arising from the popularization of cloud computing, the need for mobility, and voluminous information applications.

SDN's goals include the ability to quickly implement network innovations to quickly and drastically simplify and automate the process of managing large networks. However, many of the principles of SDN are not completely new — for example, the ability to program a network was tested in Active Networking in the 90s, and the selection of the control level was presented in the 2000s by the IETF ForCES Working Group . Unfortunately, many of the results of such studies are not widespread.

Our goal today is to look at the prospects for the development of SDN and OpenFlow, first explored in the ONF ( Open Networking Foundation ), which currently includes all major manufacturers of network equipment: Alcatel-Lucent, Cisco, Dell, Ericsson, Extreme Networks, HP, Huawei , IBM, Intel, Juniper Networks.

SDN Usage Examples

The use of SDN is a driving force in the evolution of OpenFlow. The number of examples of using SDN, based on the use of OpenFlow, has increased in recent years. We will consider two of the most significant for the evolution of OpenFlow case, which quite extensively illustrate the diversity of SDN issues: cloud data centers and unified communications in enterprises.

The data center goes to the cloud

Computing resources in cloud data centers are created automatically in minutes. Typically, however, manual network control with the help of a person affects the operation of the command line interface for each network element, and thus is much slower. Network disruptions can have a wide impact, and the effects of network changes are difficult to predict. One approach to this new dynamic paradigm is to separate the network from computational instability and to provide only flat static communication services.

However, cloud-based data centers are creating new requirements for the core network. For example, traffic from different tenants must be segregated, both to improve security and to improve performance.

Various network functions, such as Firewall, Internet traffic recognition ( DPI ) and load balancing systems, must be added as and when required by the client. Thus, network functions should be more closely related to computational functionality than ever, since network policies must comply with computational policies, and the usual static network settings become insufficient.

A common solution today is to deploy SDN to dynamically configure a static network. VSwitch , an open source softswitch, dynamically routes for each server packets from virtual machines ( VMs ) along different static paths acting on the network.

The data center manager manages the API (application programming interface) to apply new requirements for connecting to the network controller when changes are made to the computational data. The network controller can then use an API, such as OpenFlow, to apply network access requirements and policies to the VSwitch software switch.

An example of the evolution of OpenFlow may be the addition of multi-channel support, due to the desire to use OpenFlow in cloud data centers. On modern versions of OpenFlow, the ability to encapsulate metadata is included - the basic primitive in creating a logical network over the existing one.

Cloud Corporate Communications

Interactive media applications, such as video conferencing or a remote workplace, that require Quality of Service ( QoS ) on the network to guarantee application performance — are either deployed on expensive dedicated networks, or suffer from poor quality non-dedicated networks.

The QoS for these applications is critical and it must be maintained in end-to-end mode based on global network policy, which makes the deployment and configuration process difficult. Therefore, existing QoS implementations are primarily limited to a QoS specification based on static solutions and partly on the network aspect.

For today's networks, there is no effective way to identify the processes that require QoS, and the policies that apply to each of them. In addition, the access control system requires a computational approach and the configuration of suitable QoS over the incoming flow QoS.

The QoS resource allocation also needs to be dynamically adapted to meet the various traffic needs and QoS sensitive workflows. The evolution of SDN can help automate the QoS configurations of the entire network for Unified Communications, as demonstrated at the OpenFlow Lync presentation from HP and Microsoft.

MS Lync is a product for corporate communications and messaging, including audio and video conferencing, remote desktop access using the end client on a PC and the central Lync server for managing communications sessions and policies.

The VAN controller product is an SDN controller that can configure network controllers using the OpenFlow protocol. The Lync server and the VAN controller communicate via the north SDN application programming interface (northbound API), through which the application presents the low-level details to the application upstream in the system architecture.

A QoS module on an SDN controller is needed to monitor network resource usage and can apply specific QoS measures to flows in the network based on QoS policies. QoS module can easily map global QoS policies and network.

When starting a new session, the Lync server can access the session requirements, such as the necessary bandwidth and end-to-end delay, to check with the SDN controller whether there are available resources. The QoS controller module can determine the policy applicable to a particular connection based on global QoS policies, characteristics transmitted by the Lync server, the state of other QoS connections existing on the network, and, if necessary, based on user identification (obtained using a directory service such as LDAP ). The QoS module then programs this policy to various switches using OpenFlow.

The goal here is not only to provide the required QoS, but also to scale the resources used. If the quality of the session is unacceptable, the network status can be analyzed in real time and action can be taken (for example, call forwarding). Autonomous managed corporate networks are subject to similar global QoS control.

Future comes

The two cases of use of SDN that we have considered are designed to meet the needs that are poorly addressed by existing networks. In the following articles we will take a closer look at the basic elements of SDN, and also talk about the evolution of routing and wireless connections.

All modern cloud services companies recognize that the SDN development prospects are global, and a certain amount of effort is required to take SDN to a new level of use. Nevertheless, the requirements for SDN are also enormous, and the number of organizations and foundations involved in its development numbers dozens.

Analyzing the state of the market or even the client traffic of Cloud4Y itself, it can be noted that the demand for cloud services is growing steadily, and the importance of developing SDN in this sense is undeniable. That is why it is possible to assert without any doubt that the programmable future is not far off.