Directory:
----OpenFlow Origins
----OpenFlow Basic composition,
--------OpenFlow Switch,
--------Flowvisor,
--------Controller
Origin: OpenFlow originated from the Clean Slate project team at Stanford University. In 2006, Stanford student Martin Casado led a project ethane on cybersecurity and management. The project view is a centralized controller that allows network administrators to easily define security controls based on network traffic. Inspired by this, Martin and his mentor Nick McKeown found that if the design of the ethane is more generalized, the traditional network equipment data forwarding and routing control functions are separated, through the centralized controller with standardized interface to the various network equipment management and configuration, This will provide more possibilities for the design, management, and use of network resources. They then put forward the concept of OpenFlow, and in 2008 published in the ACM SIGCOMM openflow:enabling Innovation in Campus networks paper. It not only expounds the working principle of openflow, but also illustrates the application scenario: (1) The support of the Campus Network Center to Experimental Communication Protocol, (2) network management and Control access, (3) network isolation and VLAN, (4) WiFi-based mobile network, (5) Non-IP network, (6) network packet-based processing.
openflow Basic composition : OpenFlow switch, flowvisor,controller three parts.
wherein, the openflow switch carries on the data layer forwarding. Flowvisor virtualization of the network. Controller controls the network and realizes the function of the control layer.
the
openflow switch consists of a flow table, a secure channel, and a OpenFlow protocol.
The flow table consists of a number of flow table items, each of which is a forwarding rule. The packet that goes into the switch is queried by the flow table to obtain the destination port for forwarding. The flow table entry consists of a header field, a counter and an operation, where the head field is a 10-tuple, which is the identification of the flow table item, and the counter is used to count the statistics of the flow table entry, and the operation indicates what the packet that matches the flow table item should do. The secure channel is the interface that connects the OpenFlow switch to the controller. The controller controls and manages the switch through this interface, while the controller receives events from the switch and sends packets to the switch. Switches and controllers communicate through secure channels, and all information must be executed in the format specified in the OpenFlow protocol. The OpenFlow protocol is used to describe the standard of information used for interaction between the controller and the switch, as well as the interface standards of the controller and switch. The core part of the protocol is the set of information structures used for openflow protocols. The OpenFlow protocol supports three types of information: controller-to-switch,asynchronous and symmetric, each of which has more than one child type. The Controller-to-switch information is initiated by the controller and is used directly to detect the status of the switch. Asynchronous information is initiated by the switch and is typically used to update the controller's network events and change the status of the switch. Symmetric information can be initiated by a controller or switch without a request.
flowvisor is the network virtual layer between hardware structure components and software. Flowvisor allows multiple controls to control a single openflow switch at the same time, but each controller can control only one virtual network (that is, slice) that passes through the openflow switch. Therefore, the test platform established by Flowvisor can allow multiple network experiments to be performed simultaneously on different virtual networks without affecting the forwarding speed of commercial streams. The Flowvisor is compatible with general commercial switches and does not require the use of programmable hardware such as FPGAs and network processors.
the
controller implements the control layer function. OpenFlow realizes the separation of the data layer and the control layer, in which the Controller realizes the function of the control layer by forwarding the data layer exchange of the openflow switch. The controller controls the flow tables in the OpenFlow switch through the standard interface of the OpenFlow protocol, which enables centralized control of the entire network. All of this is done by running NOx, so NOx is like an operating system for OpenFlow networks. In addition, applications such as Plug-n-serve, Openroads, and Openpipes can also be run on NOx. Plug-n-serve controls the network and the load on the server by providing a data transfer path, which enables load balancing and reduced response time. Openroads is a framework to support the mobility of openflow wireless networks. Openpipes can test each submodule in a network system by moving each sub-module, and can decide how to divide the design unit.
Next-generation network interconnect technology-OpenFlow
