网络安全检测|网络安全服务|网络安全扫描-香港墨客投资移动版

Abstract: As power consumption of the internet has been growing quickly in recent years, saving energy has be- come an important problem of networking research. Software-Defined Networking (SDN) brings excellent opportunities to improve network performance and reduce energy consumption by flexible centralized control. However, due to budget constraints and technique limitations, ISPs can upgrade only a limited number of conventional switches in backbone networks to SDN devices at one time. In this paper, we propose one heuristic scheme for incrementally deploy SDN switches in hybrid SDNs, the objective of which is to achieve energy saving by rerouting the flows to shut down idle links and switches as many as possible. Our solution can achieve two objectives: 1) maximizing the network control ability with a given SDN switches upgrading budget constraint, and 2) maximizing energy saving by shutting down idle links and switches with deployed SDN switches. The results of evaluations show that our scheme can achieve 95% of the number of flows controlled with only 10% of upgrading cost, and it also can achieve saving more about 10% of the total power consumption when compared to the existing solutions.

Key words: Software-Defined Networking, Switch deployment, Energy saving, Network management.

1 Introduction

Software-Defined Networking (SDN) technique is widely used in recent years, and it separates the network control plane from the packet forwarding plane and provides applications with an ab- stracted centralized view of the distributed network state [1]. Mi- crosoft, Google, Amazon and other companies deploy their SDNs and obtain a lot of benefits [2]. At the same time, energy con- sumption from the data centers and ISP networks is increasing fast. With the expansion of network scale, energy consumption is even demonstrated to surpass the equipment cost. The work [3] points out that the ratio of Internet energy consumption accounts for up to 10% of the worldwide energy consumption. Therefore, energy saving is important not only for economical and environmental reasons, but also for the sustainable growth of Internet, due to the challenges imposed by power delivery to and heat removal from giant data centers [4,5]. Besides, SDN switches cannot be deployed at one time due to the funding and technical constraints. So it is a good method to solve the issue of energy saving using the incre- mental deployment of SDN switches.

Generally speaking, the network upgrade is a complex opera- tion. ISPs consider not only the budget constraints but also the normal network operation [6,7]. Thus, it is not practical to up- grade all network devices (e.g., switches and routers) in networks to SDN devices at one time. In the existing work [1,8–10], the au- thors state that the SDN switches and the current Internet can co- exist with each other, and the SDN networks can be incrementally deployed to the Internet. Therefore, ISPs should trade off finan- cial consideration and the network control ability (NCA) to deploy1 SDN switches in existing networks [11]. The hybrid SDNs, which are composed of SDN devices and traditional network equipment, will coexist during a long time [12]. Network operators must be able to incrementally deploy SDN switches in order to control and manage the network more flexibly.

Energy consumed by network devices such as switches is not in proportion to the utilization of its links, which means energy consumption is high compared to the amount of carried traffic in the network. On the whole, energy efficiency of the Internet is very low [13,14]. Generally speaking, turning on a switch consumes most of its power, and getting the utilization of a link from idle to full only consumes an extra 8 percent of power [15]. Although all the nodes are active all the time, it is shown that at most 40% percent of the capacities of links are used [16]. Therefore, we can turn off links and switches that are unnecessary in the network to save energy. Having a global network view, the SDN controller is able to determine the power sates and routing decisions in the net- work. Moreover, the SDN controller can install flow table entries on switches to encapsulate Multi-Protocol Label Switching (MPLS) la- bels for each packet to indicate the routing information of forward- ing path. We can achieve the purpose of energy saving by precisely controlling the forwarding path of each flow using SDN controller. Moreover, under the constraints of capital and manpower, the de- ployment of SDN requires an extended period. So we can solve the issue of energy saving using the incremental deployment of SDN switches.

* Corresponding author.

E-mail addresses: [email protected] (X. Jia),

[email protected], [email protected], [email protected] (Y. Jiang), [email protected] (G. Shen).

Our objective is to minimize network energy consumption by deploying SDN switches under the budget constraint. To achieve the efficient energy saving, we are faced with two challenges: 1) given a limited number of SDN switches, how to incrementally de- ploy them to achieve the maximum NCA improvement. 2) Fixed SDN switches deployment location, how to maximize energy sav- ings by rerouting the flows. Because of the distributed control in traditional networks, it is difficult to coordinate between devices. But in SDN networks the SDN controller can precisely control the flow path by encapsulating MPLS labels to packets. In this way, we propose the Exact Path Control (EPC), which is the flow-level explicit path control scheme to turn off links and switches that are unnecessary in the network to save energy. Moreover, the ad- vantage of the flexible segment routing among SDN switches con- tributes to the energy saving. The main contributions of our work can be summarized as follows: