| With the development of the Internet and cloud computing,the traditional architecture of network cannot full-fill the need for flexibility for enterprise users.Software Defined Network(SDN)is a new network architecture paradigm,which received a lot of attention.SDN split the control plane and the data plane,so that the two planes can evolve independently,which also improves programmability of the network.SDN often uses logically centralized control plane.The control plane connects with the data plane(switches)using control network.Data plane focuses on forwarding packets at line rate,control plane installs forwarding rules according to business logic on data plane devices via control messages.OpenFlow is the de-facto standard control protocol.OpenFlow provides low-level general control functionalities,which brings great flexibility to the control plane.But this model bring several problems: 1.The control latency between control plane and data plane.2.Logical centralized control plane may have some scalability issues.3.Low-level control messages bring overhead to both control plane and control network.To mitigate those problems,we designed and implemented a two-layer SDN framework.We introduce a new local control layer to provide the global control plane with high-level,domain specific control interface.And the new layer can also handle some local switch events to decrease the load both on the global control plane and the control network,and decrease the control latency of these events.Also,from software engineering aspect,we open the opportunity of creating reusable modules and make compatibility support to different southbound APIs by introducing the local control layer.We implemented a prototype system of the Ryuo SDN framework.We designed and performed several experiments to compare the performance of the Ryuo SDN framework with existing SDN frameworks.We used performance metrics such as control traffic,control latency and control throughput.Then we describe how to implement SDN application using Ryuo by showing some use cases.Finally,we depicted our future plan for improving the Ryuo SDN framework. |
