• Journal of the Korea Society of Computer and Information
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• v.16 no.4
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• pp.29-42
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• 2011

This study deals with the assessment indices about greening performance of datacenter. To do this, we survey existing standards and guidelines about datacenter. Those are used constructing new model of datacenter regarding greening performance. In this model, the relationship between major components will be represented by job-energy-thermal notation. Items, criteria and methods are created in order to complete the assessment indices. The existing assessment indices of the datacenter level and equipment level are investigated. Parameters, the degree of virtualization and energy efficiency also affects the performance of the green performance. Finally, to determine the improvements, the proposed indices is compared with the existing assessment tools.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.11
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• pp.3955-3966
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• 2014

With the exponentially increasing Internet traffic and emergence of more versatile and heterogeneous applications, the design of datacenter networks (DCNs) is subject to unprecedented requirements for larger capacity and more flexible switching granularities. Envisioning Optical-Orthogonal Frequency Division Multiplexing (O-OFDM) as a promising candidate for such a scenario, we motivate the use of O-OFDM as the underlying switching technology in order to provide sufficient switching capacity and elastic bandwidth allocation. For this purpose, this article reviews the recent progresses of DCN deployment and assesses the scenario where the O-OFDM transmission and switching technology is employed in the underlying transport plane. We discuss the key issues of the datacenter-oriented O-OFDM optical networks, and in particular, elaborate on a number of open issues and solutions including system interconnection architecture, routing and resource assignment, survivability, and energy-efficiency.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.9 no.5
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• pp.1606-1623
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• 2015

Optical switching will be applied in datacenter networks because electronic switching is costly and power-consuming. In this paper, considering the ring-based interconnection using optical switching in the core of a datacenter, we study the home circuit (HC) construction for the labeled optical burst switching with home circuit (LOBS-HC), a new paradigm trying to share wavelengths among the HCs from the same source. In particular, aiming to construct HCs dynamically and properly, a scheme named optimal path matching and symmetric HC matching (OPM-SHM) is proposed. The main idea of OPM-SHM is to dynamically construct HCs by sharing wavelength(s) not only among the same-source HCs but also with symmetric HCs which have different sources other than the original LOBS-HC features. The simulation results demonstrate that OPM-SHM achieves better performance than some other methods in terms of burst loss rate and wavelength utilization of physical links. More specially, it maintains good load balancing for the datacenter network using an LOBS-HC ring. In addition, due to the symmetric feature of SHM, the proposed scheme can decrease the upper bound of the average hop count of the routing paths to half of the ring size.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.18 no.4
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• pp.183-189
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• 2018

With the recent advancement of vehicle wireless communication technology, many vehicular clouds have been proposed. The existing research focused on cloud services through data collection based on vehicular networks of mobile V2V (Vehicle-to-Vehicle) and V2I (Vehicle-to-Infrastructure). In this paper, we present a vehicular datacenter model that utilizes the vehicle in the parking space as a resource for the datacenter. Also, we derive resource allocation strategy based on the expected execution time considering the leave rate of each vehicle in our vehicular datacenter model. Simulation results show that our proposed resource allocation strategies outperform the existing strategy in terms of mean execution time.

• Proceedings of the Korean Society of Computer Information Conference
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• 2016.01a
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• pp.57-58
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• 2016

ICT의 보급, 확대는 데이터 센터의 중요성을 높이고 보다 성능이 좋으며 체적 당 소비전력이 큰 서버를 수용할 수 있는 데이터 센터의 수요를 창출하고 있다. 현재 데이터 센터는 데이터 센터 활용 시에 구성요소들에 대한 상당한 대역폭을 필요로 하나 현 데이터센터에 적용된 토폴로지는 고성능 IP 스위치/라우터를 사용하더라도 네트워크 엣지 계층에서는 기본 활용도의 50%의 bandwidth밖에 지원하지 못한다. 따라서 이러한 문제를 해결하기 위해 OMNeT++을 이용하여 데이터 센터 토폴로지 중 하나인 Fat-tree를 모델링하고 데이터 센터 제반 환경을 구축, latency, power consumption, heat dissipation 등의 기준지표를 성능평가 하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.10
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• pp.4787-4807
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• 2016

Although the dense interconnection datacenter networks (DCNs) (e.g. FatTree) provide multiple paths and high bisection bandwidth for each server pair, the single-path TCP (SPT) and ECMP which are widely used currently neither achieve high bandwidth utilization nor have good load balancing. Due to only one available transmission path, SPT cannot make full use of all available bandwidth, while ECMP's random hashing results in many collisions. In this paper, we present OFPT, an OpenFlow based Parallel Transport framework, which integrates precise routing and scheduling for better load balancing and higher network throughput. By adopting OpenFlow based centralized control mechanism, OFPT computes the optimal path and bandwidth provision for each flow according to the global network view. To guarantee high throughput, OFPT dynamically schedules flows with Seamless Flow Migration Mechanism (SFMM), which can avoid packet loss in flow rerouting. Finally, we test OFPT on Mininet and implement it in a real testbed. The experimental results show that the average network throughput in OFPT is up to 97.5% of bisection bandwidth, which is higher than ECMP by 36%. Besides, OFPT decreases the average flow completion time (AFCT) and achieves better scalability.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.16 no.7
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• pp.2257-2285
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• 2022

Cyber-physical systems (CPS) have been growing exponentially due to improved cloud-datacenter infrastructure-as-a-service (CDIaaS). Incremental expandability (scalability), Quality of Service (QoS) performance, and reliability are currently the automation focus on healthy Tier 4 CDIaaS. However, stable QoS is yet to be fully addressed in Cyber-physical data centers (CP-DCS). Also, balanced agility and flexibility for the application workloads need urgent attention. There is a need for a resilient and fault-tolerance scheme in terms of CPS routing service including Pod cluster reliability analytics that meets QoS requirements. Motivated by these concerns, our contributions are fourfold. First, a Distributed Non-Recursive Cloud Model (DNRCM) is proposed to support cyber-physical workloads for remote lab activities. Second, an efficient QoS stability model with Routh-Hurwitz criteria is established. Third, an evaluation of the CDIaaS DCN topology is validated for handling large-scale, traffic workloads. Network Function Virtualization (NFV) with Floodlight SDN controllers was adopted for the implementation of DNRCM with embedded rule-base in Open vSwitch engines. Fourth, QoS evaluation is carried out experimentally. Considering the non-recursive queuing delays with SDN isolation (logical), a lower queuing delay (19.65%) is observed. Without logical isolation, the average queuing delay is 80.34%. Without logical resource isolation, the fault tolerance yields 33.55%, while with logical isolation, it yields 66.44%. In terms of throughput, DNRCM, recursive BCube, and DCell offered 38.30%, 36.37%, and 25.53% respectively. Similarly, the DNRCM had an improved incremental scalability profile of 40.00%, while BCube and Recursive DCell had 33.33%, and 26.67% respectively. In terms of service availability, the DNRCM offered 52.10% compared with recursive BCube and DCell which yielded 34.72% and 13.18% respectively. The average delays obtained for DNRCM, recursive BCube, and DCell are 32.81%, 33.44%, and 33.75% respectively. Finally, workload utilization for DNRCM, recursive BCube, and DCell yielded 50.28%, 27.93%, and 21.79% respectively.

• Annual Conference of KIPS
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• 2015.04a
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• pp.156-159
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• 2015

최근 콘텐츠 전송 네트워크(content delivery network, CDN)와 클라우드 컴퓨팅(cloud computing)을 결합하여 효과적으로 콘텐츠를 전달하기 위한 방법이 대두되고 있으며 이와 같이 클라우드 컴퓨팅과 결합하여 서비스되는 CDN을 클라우드 CDN 이라고 칭한다. 본 논문에서는 클라우드 CDN 환경에서의 효과적인 가상 머신 (virtual machine, VM) 관리를 위한 캐시서버(caching server)로써의 VM의 네트워크 I/O 성능 분석을 다룬다. 해당 성능 분석은 엔드 유저(end-user)들과 캐시서버 간 동영상 스트리밍(streaming)을 통하여 이루어졌으며 해당 캐시 서버의 네트워크 I/O 성능에 영향을 주는 다양한 경우에 대하여 진행되었다. 본 논문에서의 성능 분석은 클라우드 CDN 환경에서의 데이터센터(datacenter) 선택 및 요청 라우팅(routing) 등에 적용될 수 있다.

• Journal of information and communication convergence engineering
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• v.16 no.4
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• pp.264-270
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• 2018

In our research study, we aim at optimizing multiple load in cloud, effective resource allocation and lesser response time for the job assigned. Using Hadoop on datacenter is the best and most efficient analytical service for any corporates. To provide effective and reliable performance analytical computing interface to the client, various cloud service providers host Hadoop clusters. The previous works done by many scholars were aimed at execution of workflows on Hadoop platform which also minimizes the cost of virtual machines and other computing resources. Earlier stochastic hill climbing technique was applied for single parameter and now we are working to optimize multiple parameters in the cloud data centers with proposed heuristic hill climbing. As many users try to priorities their job simultaneously in the cluster, resource optimized workflow scheduling technique should be very reliable to complete the task assigned before the deadlines and also to optimize the usage of the resources in cloud.

• Annual Conference of KIPS
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• 2013.11a
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• pp.192-194
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• 2013

가상화 기술의 발달은 클라우드 데이터센터(cloud datacenter)에서의 서버 통합(server consolidation)을 지원하며 이를 통하여 물리적 머신(physical machine, PM) 관리 비용을 감소시킬 수 있다. 그러나 서버가 통합됨에 따라 가상 머신(virtual machine, VM) 간섭이 생길 수 있고 이는 성능 감소의 원인이 된다. 따라서 VM 간섭과 PM 관리 비용을 감소시키는 것은 트레이드오프(trade-off)를 이루며 본 논문에서는 이를 해결하기 위하여 VM 간섭 계측(quantizing)을 위한 기법과 비용 효율적 VM 배치(placement)를 위한 휴리스틱(heuristics)을 제안한다.