NFV和SDN在云数据中心的协同部署

为了解决云数据中心网络面临的诸多挑战,本文提出了一种NFV和SDN在云数据中心的协同解决方案,分析了部署方案中的关键网元,给出了NFV基于传统网络环境和基于overlay网络环境的两种部署架构,并分析NFV和SDN协同部署时需要重点关注的问题。     

基于SDN的云数据中心网络

随着云计算技术的发展和成熟,传统网络架构和技术已经难以适应云数据中心的发展.SDN技术为云数据中心网络部署提供了新的解决方案,被认为是云数据中心网络架构的未来演进方向.本文首先分析了云数据中心发展面临的主要问题和SDN技术特点,然后对比分析业界几种主流的SDN实现方案,考虑技术成熟度和部署难易的问题,深入分析了SDN Overlay方案,最后探讨了云数据中心网络的发展趋势.     

基于SDN的云数据中心

移动互联网、云计算等新型业务的高速增长,一方面促使传统的IDC向云计算数据中心转变,另一方面越来越多的应用和数据集中到云端,使得云数据中心的规模急剧增长,传统网络架构和技术已经难以适应云数据中心的发展,如多租户网络隔离、地址复用、VPC(虚拟专有云)、东西向流量控制、QoS和安全控制、自动化网络配置以及大二层网络需求等。SDN作为近期兴起的一种新型网络技术,被认为是解决云数据中心诸多网络问题的重要手段。首先分析云计算引入对数据中心网络带来的主要挑战和问题,然后提出解决这些问题的思路;在比较几种业界主流SDN技术方案后,提出了基于overlay SDN的云数据中心网络解决方案,并深入分析了其实现原理;最后探讨了云数据中心网络的发展趋势。     

云数据中心的SDN解决方案

SDN的设计理念是对网络资源进行池化管理,自动化实现网络资源的按需申请和调用,加速数据中心业务的上线周期。首先介绍了数据中心SDN的核心思想和SDN开放架构全景图,然后介绍了SDN网络模型和SDN业务部署方案,最后阐述了华为CloudFabric云数据中心网解决方案。     

基于NFV/SDN的运营商网络重构

NFV/SDN技术的不断发展成熟,在特定现网场景下,NFV/SDN技术的部署方案越来越成熟,NFV/SDN技术的成熟为运营商实现网络重构提供了技术支撑.本文将通过分析NFV/SDN技术对运营商IP承载网络的影响,分析NFV/SDN在数据中心和网络接入侧的应用方案,以期对提升网络承载能力,控制网络建设成本以及推动网络能力货币化等发挥重要作用,探讨运营商网络重构未来的发展方向.     

软件定义网络发展的理论研究

近年来,软件定义网络SDN（Software Defined Networking）已经成为科研机构、运营商、云服务提供商、大型数据中心以及企业网用户最为关注的网络技术。SDN作为一种新兴的控制与转发分离并直接可编程的网络架构,能摆脱传统网络设备对网络控制功能的捆绑,实现网络智能管理、快速部署与维护以及灵活扩展等功能。为此,我们将回顾SDN发展的早期工作,对其体系架构与发展的阶段性研究状况进行归纳总结,并对SDN未来的发展进行展望。     

云数据中心SDN/NFV组网方案、测试及问题分析

随着科技的发展,SDN/NFV组网的应用对于我国网络的发展具有非常重要的意义。SDN/NFV组网在云数据中心实现了网络虚拟化,促进了云数据中心的发展。但是SDN/NFV组网中仍然有些问题需要进行进一步的探索。本文笔者对于云数据中心SDN/NFV组网方案、测试及问题进行了有效的分析。     

Nuage Networks SDN解决方案助力Numergy构建新型云基础架构

正近日,阿尔卡特朗讯旗下专注于SDN研发的Nuage Networks指出云技术提供商Numergy将在其数据中心部署Nuage Networks的SDN平台和阿尔卡特朗讯的7750业务路由器。Numergy需要一种能够将不同客户应用的需求进行抽象化的网络。Nuage Networks公司的SDN解决方案将数据中心网络虚拟化和自动化,并将数据中心置于反射环境     

基于SDN架构的数据中心网络路由算法需求分析

随着SDN技术的发展,采用基于SDN架构的数据中心网络将越来越广泛.围绕SDN技术在数据中心网络中的应用问题,分析了现代数据中心网络及SDN的技术特征,设计了SDN在现代数据中心网络中的应用架构,并以路由为视角分析总结了基于SDN的数据中心网络路由性能需求,提出了相应的解决方案,以期对我国未来数据中心网络建设路由设计提供必要的参考.     

“互联网+”时代SDN/NFV技术发展与实践

"互联网+"时代,网络面临应用层出不穷、带宽飞速增长、网络僵化等挑战、互联网需要支持海量连接,支持跨域和多样化的带宽保证、低时延和高可靠性、网络可定制等要求。为解决上述问题,文章对SDN/NFV呈现出商业部署加快、从数据中心走向广域网、商业模式创新、全产业链构建等发展趋势进行了分析,阐述了中兴通讯提出的以"云"为中心、SDN/NFV技术双轮、三层重构的ElasticNet未来网络架构,以及中兴通讯从业界在移动互联网、云数据中心、5G网络、运营商网络CO重构等方面所做的大量SDN/NFV实践和创新。软硬件分离、开放可编程、虚拟化的SDN/NFV技术是解决"互联网+"时代所面临调整挑战的希望所在。     

Preparation and Characterization of TaN ALD Precursors

High purity organic-tantalum precursors for thin film ALD TaN were synthesized and characterized.Vapor pressure and thermal stability of these precursors were studied.From the vapor pressure analysis,it was found that TBTEMT has a higher vapor pressure than any other published liquid TaN precursor,including TBTDET,TAITMATA,and IPTDET.Thermal stability of the alkyl groups on the precursors was investigated using a 1H NMR technique.The results indicated that the tertbutylimino group is the most stable group on TBTDET and TBTEMT as compared to the dialkylamido groups.Thermal stability of TaN precursors decreased in the following order:TBTDET ＞ PDMAT ＞ TBTEMT.In conclusion,precursor vapor pressure and thermal stability were tuned by making slight variations in the ligand sphere around the metal center.     

Curved crystal spectrometer for the measurement of X-ray lines from laser-produced plasmas

In order to diagnose the laser-produced plasmas, a focusing curved crystal spectrometer has been developed for measuring the X-ray lines radiated from a laser-produced plasmas. The design is based on the fact that the ray emitted from a source located at one focus of an ellipse will converge on the other focus by the reflection of the elliptical surface. The focal length and the eccentricity of the ellipse are 1350 mm and 0.9586, respectively. The spectrometer can be used to measure the X- ray lines in the wavelength range of 0.2-0.37 nm, and a LiF crystal （200） （2d = 0.4027 nm） is used as dispersive element covering Bragg angle from 30° to 67.5°. The spectrometer was tested on Shengnang- Ⅱ which can deliver laser energy of 60-80 J/pulse and the laser wavelength is 0.35 μm. Photographs of spectra including the 1 s2p ^1P1-1s^2 ^1S0 resonance line（w）, the 1s2p ^3P2-1s^2 1S0 magnetic quadrupole line（x）, the 1s2p ^3P1-1 s^2 ^1S0 intercombination lines（y）, the 1 s2p ^3S~1-1 s^2 ^1S0 forbidden line（z） in helium-like Ti Ⅹ Ⅺ and the 1 s2s2p ^2P3/2-1 s622s ^2S1/2 line（q） in lithium-like Ti Ⅹ Ⅹhave been recorded with a X-ray CCD camera. The experimental result shows that the wavelength resolution（λ/△ 2） is above 1000 and the elliptical crystal spectrometer is suitable for X-ray spectroscopy.     

Electronic Structure of Semiconductor Nanocrystals

This paper reviews our recent development of the use of the large-scale pseudopotential method to calculate the electronic structure of semiconductor nanocrystals, such as quantum dots and wires, which often contain tens of thousands of atoms. The calculated size-dependent exciton energies and absorption spectra of quantum dots and wires are in good agreement with experiments. We show that the electronic structure of a nanocrystal can be tuned not only by its size,but also by its shape. Finally,we show that defect properties in quantum dots can be significantly different from those in bulk semiconductors.     

Critical Stage Rule-Based Real Time Dispatch（RTD）System in Highly-Mixed-Products （HMP） FAB

An improving utilization and efficiency of critical equipments in semiconductor wafer fabrication facilities are concerned. Semiconductor manufacturing FAB is one of the most complicated and cost sensitive environments. A good dispatching tool will make big difference in equipment utilization and FAB output as a whole. The equipment in this paper is In-Line DUV Scanner. There are many factors impacting utilization and output on this equipment group. In HMP environment one of the issues is changing of reticule in this area and idle counts due to load unbalance between equipments. Here we'll introduce a rule-based RTD system which aiming at decreasing the number of recipe change and idle counts among a group of scanner equipment in a high-mixed-products FAB.     

GaAsSb/InAlAs PA DHBTs Grown by Production MBE

The epi material growth of GaAsSb based DHBTs with InAlAs emitters are investigated using a 4 × 100mm multi-wafer production Riber 49 MBE reactor fully equipped with real-time in-situ sensors including an absorption band edge spectroscope and an optical-based flux monitor. The state-of-the-art hole mobilities are obtained from 100nm thick carbon-doped GaAsSb. A Sb composition variation of less than ± 0.1 atomic percent across a 4 × 100mm platen configuration has been achieved. The large area InAlAs/GaAsSb/InP DHBT device demonstrates excellent DC characteristics,such as BVCEO＞6V and a DC current gain of 45 at 1kA/cm2 for an emitter size of 50μm × 50μm. The devices have a 40nm thick GaAsSb base with p-doping of 4. 5 × 1019cm-3 . Devices with an emitter size of 4μm × 30μm have a current gain variation less than 2% across the fully processed 100mm wafer. ft and fmax are over 50GHz,with a power efficiency of 50% ,which are comparable to standard power GaAs HBT results. These results demonstrate the potential application of GaAsSb/InP DHBT for power amplifiers and the feasibility of multi-wafer MBE for mass production of GaAsSb-based HBTs.     

Noise character analysis and the restraint of self-pulsation laser diodes

We calculate the Langevin noise sources of self-pulsation laser diodes, analyze the effects of active region noise and saturable-absorption region noise on the power fluctuation as well as period fluctuation, and propose a novel method to restrain the noise effects. A visible SIMULINK model is established to simulate the system, The results indicate that the effects of noise in absorption region can be ignored; that with the increase of DC injecting current, the noise effects enhance power jitter, and nevertheless, the period jitter is decreased; and that with external sinusoidal current modulating the self-pulsation laser diode, the noise-induced power jitter and period jitter can be suppressed greatly. This work is valuable for clock recovery in all-optical network.     

High-quality single-crystal CdSe nanoribbons and their optical properties

Large-scale synthesis of single-crystal CdSe nanoribbons is achieved by a modified thermal evaporation method, in which two-step-thermal-evaporation is used to control CdSe sources＇ evaporation. The synthesized CdSe nanoribbons are usually several micrometers in width, 50 nm in thickness, and tens to several hundred micrometers in length. Studies have shown that high-quality CdSe nanoribbons with regular shapes can be obtained by this method. Room-temperature photolumines-cence indicates that the lasing emission at 710 nm has been observed under optical pumping （266 nm） at power densities of 25-153 kW/cm^2. The full width half maximum （FWHM） of the lasing mode is 0.67 nm     

Propagation of hermite-cosh-gaussian beams passing through ABCD optical system with an annular aperture

By using the expansion of the aperture function into a finte sum of complex Gaussian functions, the corresponding analytical expressions of Hermite-cosh-Gaussian beams passing through annular apertured paraxially and symmetrically optical systems written in terms of ABCD matrix were derived, and they could reduce to the cases with squared aperture. In a similar way, the corresponding analytical expressions of cosh-Gaussian beams through annular apertured ABCD matrix were also given. The method could save more calculation time than that by using the diffraction integral formula directly.     

Influence of polarization extinction ratio on distributed polarization coupling detection

Distributed polarization coupling in polarization-maintaining fibers can be detected by using a white light Michelson interferometer. This technique usually requires that only one polarization mode is excited. However, in practical measurement, the injection polarization direction could not be exactly aligned to one of the principal axes of the PMF, so the influence of the polarization extinction ratio should be considered. Based on the polarization coupling theory, the influence of the incident polarization extinction on the measurement result is evaluated and analyzed, and a method for distributed polarization coupling detection is developed when both two orthogonal eigenmodes are excited.     

Call for Papers

正Communications—VLSI Researches and industries of telecommunications have been growing rapidly in the last 20 years and will keep their high growing pace in the next decade.The involved researches and developments cover mobile communications,highway and last-mile broadband communication,domain specific communications,and emerging D2D M2M communications.Radio communication steps into its