Multiobjective evolutionary approach to cost-effective traffic grooming in unidirectional SONET/WDM rings

Traffic grooming in optical networks is the process of multiplexing and demultiplexing low-speed traffic streams onto high-speed wavelengths. The research in the domain of traffic grooming mainly focuses on minimizing number of SONET add/drop multiplexers (SADMs) in SONET/WDM rings and it has been shown that they can potentially be reduced by careful assignment of low-speed traffic streams onto high-speed wavelengths. However, the cost of the network not only depends on the number of SADMs, but also the number of wavelengths and the grooming ratio. It is often the case that all of them cannot be minimized simultaneously. In this article, the problem of minimization of cost of a SONET/WDM unidirectional ring has been modeled as a multiobjective optimization problem which simultaneously minimizes the number of SADMs, the number of wavelengths, and the grooming ratio. A popular multiobjective genetic algorithm (NSGA-II) has been used as the underlying optimization tool. The resultant set of near-Pareto-optimal solutions contains a number of nondominated solutions, which the user can judge relatively and pick up the most promising one according to the problem requirements. Performance of the proposed algorithm has been demonstrated on different network topologies.

PDH,SDH／SONET技术及其应用（一）

本文论述了ＳＤＨ／ＳＯＮＥＴ技术产生和发展及应用，并从理论上对ＰＤＨＴ和ＳＤＨ／ＳＯＮＥＴ作了技术比较，此外，还介绍了ＳＤＨ传输网络结构和ＳＤＨ传送设备。     

Combining GA with Splitting Methods for Rearrangeably Nonblocking Grooming of Dynamic Traffic in SONET Ring Networks

SONET/WDM rings are widely deployed in today’s networks. To reduce the total cost of such a network, an efficient way is using the traffic grooming technique to minimize the number of add/drop multiplexers (ADMs) on the ring. Since traffic often changes frequently, the problem of supporting dynamic traffic patterns with minimum number of ADMs and wavelengths becomes incresingly important, which is referred to as grooming of dynamic traffic. In this paper, we will deal with rearrangeably nonblocking grooming of arbitrary dynamic traffic in such ring networks. We will discuss in detail the benefit of splitting methods to such a grooming way and apply them to this kind of grooming. A novel genetic algorithm (GA) approach with a hierarchical chromosome structure for each individual is proposed in combination with splitting methods to address such grooming problems. Computer simulation results under different conditions show that our algorithm is efficient in reducing both the numbers of ADMs and wavelengths.     

RPR技术及其在电力城域网中的应用

弹性分组环(RPR)作为一种新的基于分组交换的网络技术,融合了SDH/SONET和以太网的优点,是城域网数据传输的理想平台。在概述当前主流城域网技术的基础上,详细介绍了RPR及其关键技术,讨论了RPR技术在电力城域网中的应用。并指出,随着RPR技术和IEEE802.17标准的不断完善,RPR技术以其在网络安全性、带宽效率、成本等方面无可比拟的优势,将成为今后电力宽带数据网发展演进的重要技术。     

2.5Gb/s SDH/SONET指针处理器芯片实现

提出了一种2.5Gb/s同步光纤网络SDH/SONET中指针处理器芯片实现结构.指针处理器执行指针解释、通路开销性能监测功能,产生新的与系统时钟同步的STM/STS帧.指针解释模块对输入STM/STS通道的H1/H2指针进行解释,支持48通道的指针解释和每个通道的通路开销监测.采用4路总线流水线结构,77.76MHz的系统时钟,即可实时处理2.5Gb/s的SDH/SONET数据.采用TSMC 0.13μm工艺流片,技术指标符合ITU-T标准.     

利用弹性分组环技术建设新一代城域网

弹性分组环(RPR)技术是融合SDH/SONET和以太网的优点而形成的一种基于分组交换的网络技术,它已成为建设新一代城域网、实现三网合一的主要技术之一.对RPR进行介绍并与其他技术作比较,讨论了RPR的优点、关键技术及发展前景.     

A heuristic solution to SONET ADM minimization for static traffic grooming in WDM uni-directional ring networks

In recent years, minimization of add-drop multiplexers (ADMs) in wavelength division multiplexing (WDM) optical networks has gained lots of attention in both the research and commercial areas. This motivates the research presented in this paper. A heuristic algorithm is formulated for static traffic grooming in WDM uni-directional ring networks with an eye to minimize the number of required ADMs. The distinguished feature of the proposed heuristic is that it pairs up the calls of a given static traffic to approach the solution. The proposed heuristic is compared with the previous approach with same network configuration and traffic matrix to establish its effectiveness.     

在SONET/SDH架构上实现以太网透明传输的方案

介绍了在SONET／SDH架构上提供IP业务的IC解决方案：多协议芯片（MPIC，Multi-Protocol 1C）系列中的Eos(Ethernet over SONET/SDH）芯片。此款在SONET／SDH架构上实现以太网透明传输的方案较之现有的其他方案，具有高带宽利用率（虚级联）、低成本（二层处理）、易实现（标准以太网GMII和MII接口）等优势。     

Improved survivability analysis for SONET SHRs

Recently, a special type of Markov model called parametric state reward Markov model (SRMM/p) [H.C. Cankaya, V.S.S. Nair, in: IEEE Proceedings of GLOBECOM 97, vol. 1, IEEE Computer Soc. Press, Silver Spring, MD, 1997, pp. 252–256] and a set of survivability metrics comprising reliability, availability, and restorability have been proposed for the evaluation of self-healing SONET mesh networks [H.C. Cankaya, V.S.S, Nair, in: Proceedings of ISCIS 'XII, vol. 1, Bogazici University, Bogazici University Press, 1997, pp. 269–276]. The SRMM/p accommodates multiple consecutive link failures and uses topology-free approximation in order to calculate the average performance loss due to a failure. The SRMM/p is equally applicable to the analysis of self-healing SONET rings by considering a ring as a special case of a mesh topology [H.C. Cankaya, V.S.S. Nair, in: IEEE Proceedings of GLOBECOM '98, vol. 4, IEEE Computer Soc. Press, Silver Spring, MD, 1998, pp. 2276–2281]. Further, the topological uniformity and simplicity of rings allow one to include more detailed features of the network in the model so that the analysis will be more accurate. For this purpose, we propose an improved approach to the survivability analysis of self-healing SONET rings which employs a probability-tree based evaluation of the probability of various system states resulting from all possible combinations of node and link failures. The corresponding tree-construction and traversal algorithms are presented. Survivability of rings with distinctive demand patterns are studied with the improved analysis and compared experimentally. One limitation to the model is the high run-time complexity caused mainly by the disparity between transition rates amongst various states in the SRMM/p [H.C. Cankaya, V.S.S. Nair, ACM Comput. Commun. Rev. 28 (4) (1998) 268–277]. In this paper, we also present an approach to circumvent this problem by state aggregation method and compare the results in terms of run-time complexity and accuracy by conducting an experimental study.