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Central Control over Distributed Service Function Path
( Dan Li ),( Julong Lan ),( Yuxiang Hu ) 한국인터넷정보학회 2020 KSII Transactions on Internet and Information Syst Vol.14 No.2
Service Function Chaining (SFC) supports services through linking an ordered list of functions. There may be multiple instances of the same function, which provides a challenge to select available instances for all the functions in an SFC and generate a specific Service Function Path (SFP). Aiming to solve the problem of SFP selection, we propose an architecture consisting of distributed SFP algorithm and central control mechanism. Nodes generate distributed routings based on the first function and destination node in each service request. Controller supervises all of the distributed routing tables and modifies paths as required. The architecture is scalable, robust and quickly reacts to failures because of distributed routings. Besides, it enables centralized and direct control of the forwarding behavior with the help of central control mechanism. Simulation results show that distributed routing tables can generate efficient SFP and the average cost is acceptable. Compared with other algorithms, our design has a good performance on average cost of paths and load balancing, and the response delay to service requests is much lower.
Separating VNF and Network Control for Hardware-Acceleration of SDN/NFV Architecture
Tong Duan,Julong Lan,Yuxiang Hu,Penghao Sun 한국전자통신연구원 2017 ETRI Journal Vol.39 No.4
A hardware-acceleration architecture that separates virtual network functions (VNFs) and network control (called HSN) is proposed to solve the mismatch between the simple flow steering requirements and strong packet processing abilities of software-defined networking (SDN) forwarding elements (FEs) in SDN/network function virtualization (NFV) architecture, while improving the efficiency of NFV infrastructure and the performance of network-intensive functions. HSN makes full use of FEs and accelerates VNFs through two mechanisms: (1) separation of traffic steering and packet processing in the FEs; (2) separation of SDN and NFV control in the FEs. Our HSN prototype, built on NetFPGA-10G, demonstrates that the processing performance can be greatly improved with only a small modification of the traditional SDN/NFV architecture.
Random Tree Multicast Communications in Reconfigurable Network
Kaixiang Huang,Yue Chen,Julong Lan,Hongyong Jia 보안공학연구지원센터 2016 International Journal of Future Generation Communi Vol.9 No.1
To increase the security of multicast, a Random Tree Multicast (RTM) scheme in reconfigurable network was presented. By decoupling data flow and group management, and by changing the multicast tree and channel with the technology of Moving Target Defense (MTD), RTM can improve the ability of defending eavesdrop and traffic analysis with little complexity. We present the details of our scheme, analyzed its performance, and discussed its advantages over traditional schemes.
Jinlong Lu,Guoguang Cheng,Julong Che,Liansheng Wang,Guojian Xiong 대한금속·재료학회 2019 METALS AND MATERIALS International Vol.25 No.2
In this paper, the characteristics of tensile fractures and the typical inclusions in as-cast blooms and as-rolled bars are carefullyinvestigated to figure out the causes of different transverse tensile properties in two commercial non-quenched andtempered steels. In low Ca bearing steel (3 ppm), MgO–Al2O3 (MA) + MnS are main inclusions and MA oxides expresshigh ability for MnS heterogeneous nucleation. Consequently, the MnS inclusions in as-rolled bars are larger in size andsmaller in number, the transverse ductility is satisfied due to the high space distance between the MnS inclusions. However,the transverse ductility of high Ca bearing steel (9 ppm) is much poor because MnS inclusions are agminated in distribution,causing severe stress concentration. The calculation results show that CaO in CaO–MgO–Al2O3 oxides (CMA) wouldreact with Al and S in molten steels, suppressing the formation of MnS inclusions on surface of CMA oxides. An integratedillumination including the evolution processes of typical oxides in molten steels, the generation behaviors of MnS duringthe solidification, the deformation behaviors of sulfides and the relationship between sulfides and crack initiation have beenconducted based on observation results and thermodynamic calculation.
A Mechanism for Configurable Network Service Chaining and Its Implementation
( Gang Xiong ),( Yuxiang Hu ),( Julong Lan ),( Guozhen Cheng ) 한국인터넷정보학회 2016 KSII Transactions on Internet and Information Syst Vol.10 No.8
Recently Service Function Chaining (SFC) is promising to innovate the network service mode in modern networks. However, a feasible implementation of SFC is still difficult due to the need to achieve functional equivalence with traditional modes without sacrificing performance or increasing network complexity. In this paper, we present a configurable network service chaining (CNSC) mechanism to provide services for network traffics in a flexible and optimal way. Firstly, we formulate the problem of network service chaining and design an effective service chain construction framework based on integrating software-defined networking (SDN) with network functions virtualization (NFV). Then, we model the service path computation problem as an integer liner optimization problem and propose an algorithm named SPCM to cooperatively combine service function instances with a network utility maximum policy. In the procedure of SPCM, we achieve the service node mapping by defining a service capacity matrix for substrate nodes, and work out the optimal link mapping policies with segment routing. Finally, the simulation results indicate that the average request acceptance ratio and resources utilization ratio can reach above 85% and 75% by our SPCM algorithm, respectively. Upon the prototype system, it is demonstrated that CNSC outperforms other approaches and can provide flexible and scalable network services.
An Optimized Deployment Mechanism for Virtual Middleboxes in NFV- and SDN-Enabling Network
( Gang Xiong ),( Penghao Sun ),( Yuxiang Hu ),( Julong Lan ),( Kan Li ) 한국인터넷정보학회 2016 KSII Transactions on Internet and Information Syst Vol.10 No.8
Network Function Virtualization (NFV) and Software Defined Networking (SDN) are recently considered as very promising drivers of the evolution of existing middlebox services, which play intrinsic and fundamental roles in today`s networks. To address the virtual service deployment issues that caused by introducing NFV or SDN to networks, this paper proposes an optimal solution by combining quantum genetic algorithm with cooperative game theory. Specifically, we first state the concrete content of the service deployment problem and describe the system framework based on the architecture of SDN. Second, for the service location placement sub-problem, an integer linear programming model is built, which aims at minimizing the network transport delay by selecting suitable service locations, and then a heuristic solution is designed based on the improved quantum genetic algorithm. Third, for the service amount placement sub-problem, we apply the rigorous cooperative game-theoretic approach to build the mathematical model, and implement a distributed algorithm corresponding to Nash bargaining solution. Finally, experimental results show that our proposed method can calculate automatically the optimized placement locations, which reduces 30% of the average traffic delay compared to that of the random placement scheme. Meanwhile, the service amount placement approach can achieve the performance that the average metric values of satisfaction degree and fairness index reach above 90%. And evaluation results demonstrate that our proposed mechanism has a comprehensive advantage for network application.
Effect of surface quality on hydrogen/helium irradiation behavior in tungsten
Hongyu Chen,Qiu Xu,Jiahuan Wang,Peng Li,Julong Yuan,Binghai Lyu,Jinhu Wang,Kazutoshi Tokunaga,Gang Yao,Laima Luo,Yucheng Wu 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.6
As the plasma facing material in the nuclear fusion reactor, tungsten has to bear the irradiation impact ofhigh energy particles. The surface quality of tungsten may affect its irradiation resistance, and even affectthe service life of fusion reactor. In this paper, tungsten samples with different surface quality werepolished by mechanical processing, subsequently conducted by D2þ implantation and thermal desorption. D2þ implantation was performed at room temperature (RT) with the irradiation dose of 1 1021D2þ/m2 by 5 keV D2þ ions, and thermal desorption spectroscopy measurements were done from RT to900 K. In addition, He irradiation was also performed by 50 eV Heþ ions energy with the fluxes of5.5 1021 m2s1 and 1.5 1022 m2s1, respectively. Results reveal that the hydrogen/helium irradiation behavior are both related to surface quality. Samples with high surface quality has superior D2þretention behavior with less D2 retained after implantation. However, such samples are more likely togenerate fuzzes on the surface after helium irradiation. Different morphologies (smooth, wavy, pyramids)after helium irradiati