The current network is dominated by the TCP/IP protocol. From small local area networks to the Internet, the network has changed our lives. , but today’s network is not a perfect network, and there are various problems.
1: The TCP/IP protocol system is not static, but with the development of the network, problems have to be patched on the existing protocol system, making the entire protocol system very bloated.
Network equipment needs to be responsible for the generation and maintenance of data forwarding and control plane forwarding entries, so the use of multiple control protocols is necessary. This leads to the complexity of the underlying network control protocols and network equipment, making unified deployment more difficult. At the same time, the cost is increased.
3: Another disadvantage is that the entire network is closed and passive. All services are carried passively, making it very difficult to distinguish services. It is difficult for customers to upgrade existing networks based on specific services. Network and business upgrades or changes are often accompanied by the replacement of hardware equipment.
The rise of cloud computing benefits from the advancement of virtualization technology, which makes computing and storage a dynamic resource pool, thus supporting the development of cloud computing. However, the lag in network development has prevented network resources from being included in this resource pool. Therefore, the network needs to make fundamental changes to adapt to this virtual and dynamic cloud computing environment.
All kinds of problems require a new architecture to solve. So SDN came into being.
SDN is a network design concept, a design idea that subverts the traditional design. As long as the network hardware can be centralized software Management, programmability, control and forwarding are separated, and there are open interfaces, it can be considered an SDN network.
In the early era of mainframe computers, it was necessary to develop operating systems and application systems required for different chips. Later, Windows and Linux no longer directly used the underlying hardware devices, but provided a unified interface for user applications to call hardware devices. Users can develop applications based on application requirements and run them on the operating system because the entire system is programmable. The ultimate goal of SDN is to implement this model in computer network systems and provide users with an open and efficient network operating system, and the most important part of this operating system is the controller. Users can develop various APPs on the controller. For example, if you develop a switch APP on the controller, then the underlying network is a switch, or develop a traffic scheduling APP at a higher level, then users can use this APP to Control the underlying equipment to implement traffic scheduling.
Compared with today’s computer systems, the hardware Openflow device in SDN is like an X86 server, the SDN controller is the Windows Server operating system, and the network functions are various applications on Windows Server, which is equivalent to Network functions (layer 2 and 3 forwarding control, traffic scheduling, etc.) are software-based on the SDN controller.
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