SDN: Software Defined Network

The group task of the recent advanced online course is to study and present the topic at your discretion within the scope specified by the teacher. We selected SDN for the group. I thought it would be a conceptual product that no one cares about in the industry. Google found that SDN is very popular because of its scalability, some large Internet companies are also getting involved in related R & D, such as Google and Facebook. Here I will briefly summarize my understanding of SDN concepts.

Background virtualization trends

In recent years, with the rise of big data and cloud computing, virtualization technology has become increasingly important. When talking about virtualization, I have to mention an old saying in the computer industry:

The vast majority of problems in the computer world can be solved through a layered approach.

In fact, virtualization can also be understood as a layered idea. In the Application Scenario of cloud computing, virtualization technology is the originalHardware-Operating System-userLevel, addedVirtual MachineThis layer becomesHardware-Virtual Machine-Operating System-user, Use virtual machines to manage hardware resources, add? Dynamically adjusts the semantics of hardware resources.

Looking at the development history of computers, we can see that by adding? Similar cases of improving production efficiency through virtualization layers. For example, advanced languages are for assembly, and graphical interfaces are for command line. Join like this? A hierarchical solution always gives a clearer solution to the problem.

Network Virtualization

After decades of development, the Internet has played a huge role in people's production and life. The global network topology structure is complex and consists of many self-made systems. Data packets are sent from a PC in China. When asked about the hosts in the United States, they need to go through a series of routes and forwarding. The network topology nodes are dominated by gateways and routers, which are difficult to control. Some organizations also encounter complicated topology and difficult maintenance issues when setting up their own scalable and large-scale network environments.

It is assumed that the physical topology of the network can be separated, network resources can be virtualized, the complexity of the physical structure can be hidden, and the management and control of the logical layer can be unified to meet the changing network needs.

SDN and openflow are the same solutions.

Openflow and SDN

Openflow originated from Stanford's ethane project. This project tries to use a centralized controller to allow network administrators to easily define network stream-based security control policies and apply these security policies to various network devices, to achieve security control over the entire network communication. Inspired by this project, Stanford's teachers and students generalize ethane design, and forward data from traditional network devices (data plane) and control plane) the two functional modules are separated, and various network devices are managed and configured through centralized controllers with standardized interfaces. In 2008, they proposed the concept of openflow.

This distributed implementation allows the control plane to physically separate from the forwarding plane. The control plane can be executed on a server with higher computing power, rather than a router. Openflow is a separate communication protocol between the two. For the technical details of openflow, the article "Reverse Attack of Virtualization: openflow and SDN" briefly introduces openflow.

Based on the programmable features brought by openflow to the Network, some researchers proposed SDN (Software Defined Network) (2009 ). In this concept, all network devices in the network are considered as managed resources, so as to abstract the concept of a network operating system (Network OS, this network operating system abstracts the detailed details of the underlying network devices. At the same time, it also provides a unified management view and programming interface for upper-layer applications. For details about the SDN architecture, refer to SDN is a business openflow is a technology.

The relationship between SDN and openflow is like the TCP/IP protocol stack of the Internet. Openflow is the core protocol of SDN and is used to control forwarding on the forwarding plane. SDN is the upper-layer interface.

Some people think that "openflow is a technology and SDN is a business 』. Recent reports on the decline of SDN also prove the future of this "business.

SDN Development

At the same time as the rapid development of cloud computing, SDN is also rampant. Large companies such as Google and Facebook have also formed industry alliances to promote their development.

However, the current situation is not clear:

According to IDC research results, in 2013, the market value of the entire enterprise network industry was $42 billion, nearly half of which came from the 2-3 layer network switch market. SDN can only generate about $3.7 billion worth (8.8%), and it will reach this number by 2016. Compared with the previous pre-release, what is the pre-release number of IDC ?, But from the network industry perspective, SDN is still far from each other.

On the one hand, the performance of SDN still needs to be improved. On the other hand, the idea of a unified platform of SDN will bring about homogeneous hardware devices and threaten the interests of vendors, it will face resistance from vendor lock. The article "rational view of SDN" has a more specific explanation.

Although virtualization can free up productivity, it is the trend of the times, the market is cruel, just as complex instruction sets with more power consumption have defeated streamlined instruction sets in the market. We can only look forward to the steps of open-source and open-source.

Exam

• What is SDN (Software Defined networking )? *
• Openflow/SDN
• Software Defined Network (SDN): What is it, how it works, why is it important?
• SDN: still in its infancy

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SDN: Software Defined Network