OpenFlow Sample Clauses
OpenFlow. The OpenFlow [OPENFLOW] standard defines an interface between the control and forwarding layers of the SDN architecture standardized by the Open Network Foundation as described in section 2.3. OpenFlow provides network administrators a set of tools that allows them to control programmable networks. OpenFlow specification defines two principal elements, the controller and the switching device. Communication between these two elements is performed through the OpenFlow protocol. The message exchange between the controller (control plane) and the switch (data plane) is performed over a secure channel. The protocol defines three types of messages: • Controller-to-switch • Asynchronous
OpenFlow. The OpenFlow protocol and switch specification was first presented in by ▇▇▇▇▇▇▇ et al. [2008]. The concept of OpenFlow in relation to a regular switch is shown in figure 3.4. Controller HW Data Plane SW Control Plane Control Plane OpenFlow Secure Channel OpenFlow SW Data Plane HW Flow Table Regular Switch OpenFlow Switch 1▇▇▇▇://▇▇▇.▇▇▇▇▇▇▇▇▇▇▇▇.▇▇▇ 2▇▇▇▇://▇▇▇.▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇.▇▇▇/floodlight/ 3▇▇▇▇://▇▇▇▇.▇▇▇▇▇▇.▇▇/ryu/ The meaning of OpenFlow is two-fold, first of all it is a communications protocol used by SDN controllers to retrieve information and modify switch configurations. Secondly, it is a switch specification, i.e. a definition of what a switch must be capable of, in order to support OpenFlow. Figure 3.4 shows the general definition of a switch on the left-hand side, where both the data plane and control plane is located on the switch itself. The righ-hand side of the figure shows, the architecture of an OpenFlow-enabled switch. OpenFlow replaces the regular control plane in a switch with a OpenFlow-control plane, such that the data plane configuration of a switch can be controlled from an external controller. This is primarily achieved by letting the OpenFlow control plane read and write flow entries to the flow tables within a switch. The majority of OpenFlow-enabled switches and controllers on the market currently sup- ports OpenFlow version 1.0 [Open Networking Foundation, 2009] (from Dec. 2009), which is why this explanation of OpenFlow will focus on that specific version. However, newer versions of the protocol exist, where the most recent specification is version 1.4 (from Oct. 2013), but even version 1.3 (from Jun. 2012) is still in experimental ”support” in software implementations which are freely available today. This bears witness of the rapid evolvement the protocol is undertaking, and that SDN as concept is still in the early stage of its implementation. The OpenFlow specification in [Open Networking Foundation, 2009] defines a set of re- quired and optional features, that a switch must and can implement in order to support OpenFlow. The description of OpenFlow in the following, focuses on the required features, as these can be expected to be present in all OpenFlow capable equipment.