| After years of development, the Internet has gradually changed from a single type of specialized network into a huge comprehensive monster which connecting the world. Today, the increasing network application needs of Internet users and the explosive growth of network traffic has a conflict with the "old" Internet architecture.The researchers of Stanford University give their answer to this problem by SDN (short for Software-Defined Networking) After years of development, the concept of SDN has changed from simple experiments protocol into a series of network capabilities soften synonymous-separation of control and forwarding,separation of hardware and software, network virtualization and etc.,. SDN is not only the answer to the old question, but also the outlook of the future network organization form.OpenFlow protocol is one of the core technology of SDN.As the bridge between controller and the forwarding device, the current1.X version of OpenFlow protocol only support to control the network under three layers. The OpenFlow protocol needs the support of the forwarding device intelligence, so it can’t truly separate control and forwarding. Thinking of the purpose of the SDN design and the potential of OpenFlow itself, we will see the possibility of expanding the control range from four layers to seven layers.ZOpenFlow is based on OpenFlow. The method of "{offset,length}" positioning and Packets-Data operation are used in this protocol to realize protocol oblivious forwarding and intelligence minimization. Furthermore, ZOpenFlow realizes the separation of control and forwarding. ZOpenFlow not only achieves the original intention of SDN better, but also provides a network functional implementation, which is based on "controller decision, flow table carrier, forwarding device operation" mode.To verify the SDN under the framework of ZOpenFlow, the Pyretic controller and Open vSwitch forwarding equipment are modified and integrated into Mininet network experiment environment.ALG(short for Application Layer Gateway) will be selected in this paper as a representation of application layer abilities. Without the aid of third-party equipment, ALG is implemented in Mininet only by ZOpenFlow protocol. The transformation experiment environment Mininet is used to test the ALG’s function and performance to verify the SDN based on ZOpenFlow has the ability to control more than four layer of the network. |
