As all-optical networks grow with ever increasing ultra-high speed,the communication quality suffers seriously from physical layer impairments( PLIs). The same problem still exists in software defined optical network( SDON) controlled by OpenFlow. Aimed to solve this problem,a PLIs tolerance based lightpath provision scheme is proposed for OpenFlow controlled optical networks. This proposed approach not only takes the OSNR model to represent those linear PLIs factors,but also introduces those nonlinear factors into the OSNR model. Thus,the proposed scheme is able to cover most PLIs factors of each optical link and conduct optical lightpath provison with better communication quality. Moreover,PLIs tolerance model is also set up and considered in this work with some necessary extension to OpenFlow protocols to achieve better compatibility between physical layer impairments factors and various services connections. Simulation results show that the proposed scheme is able to get better performance in terms of packet loss rate and connection setup time.
With the challenge of great growing of services diversity,service-oriented supporting ability is required by current high-speed passive optical network( PON). Aimed at enhancing the quality of service( Qo S) brought by diversified-services,this study proposes an echo state network( ESN)based multi-service awareness mechanism in 10-Gigabite ethernet passive optical network( 10GEPON). In the proposed approach,distributed architecture is adopted to realize this ESN based multi-service awareness. According to the network architecture of 10G-EPON,where a main ESN is running in OLT and a number of ESN agents works in ONUs. The main-ESN plays the main function of service-awareness from the total view of various kinds of services in 10G-EPON system,by full ESN training. Then,the reservoir information of well-trained ESN in OLT will be broadcasted to all ONUs and those ESN agents working in ONUs are allowed to conduct independent service-awareness function. Thus,resources allocation and transport policy are both determined only in ONUs. Simulation results show that the proposed mechanism is able to better support the ability of multiple services.
随着越来越多工业控制系统(industrial control system,ICS)安全事件的曝光,如何防护ICS的安全已经引起了广泛的关注。然而对于ICS安全防护的研究还主要停留在理论研究和防护体系层面,缺少可以快速建立的、能够降低关键风险的具体防护措施。首先抽象出ICS通信模型,梳理ICS面临的安全风险和威胁,明确了最急迫和关键的安全需求,然后在不影响功能、效率,以及能够快速部署的前提下,设计了一种通信安全增强方案,包括对关键通信报文进行单向的身份认证和完整性检验,并结合了时间戳机制和登记机制。最后通过对增强方案的安全分析,证明其能够抵御伪装、篡改和重放等常见攻击。
