• Proceedings of the Optical Society of Korea Conference
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• 2000.02a
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• pp.116-117
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• 2000

전광 네트워크(All-optical Network)에서 중요한 기능을 담당하는 전광 교환기는 전광 교환 소자 (All-optical Switching Element)로 이루어져 있는데, 각 교환 소자들은 스위칭 모듈(SM), 라우팅 제어 처리기(RCP), 헤더 처리 모듈(HPM), 그리고 입/출력 인터페이스 모듈(IIM, OIM)로 이루어져 있다. 스위칭 시스템 내에 도착하는 패킷은 원하는 스위치의 출력단에 도착하기 전에 많은 교환 소자(SE)들을 지나가게 되는데, 이 때 수많은 패킷들이 서로 충돌하게 되며, 이 과정에서 패킷이 손실된다. (중략)

• Journal of KIISE:Information Networking
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• v.30 no.4
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• pp.520-534
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• 2003

In this paper, a performance evaluation model of the Fat-tree Network with the multiple-buffered crossbar switches is proposed and examined. Buffered switch technique is well known to solve the data collision problem of the switch network. The proposed evaluation model is developed by investigating the transfer patterns of data packets in a switch with output-buffers. Two important parameters of the network performance, throughput and delay, are then evaluated. The proposed model takes simple and primitive switch networks, i.e., no flow control and drop packet, to demonstrate analysis procedures clearly. It, however, can not only be applied to any other complicate modern switch networks that have intelligent flow control but also estimate the performance of any size networks with multiple-buffered switches. To validate the proposed analysis model, the simulation is carried out on the various sizes of Fat-tree networks that uses the multiple buffered crossbar switches. Less than 2% differences between analysis and simulation results are observed.

• Journal of KIISE:Information Networking
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• v.34 no.3
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• pp.203-217
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• 2007

In this paper, a performance evaluation model of Networks with the multiple-buffered crossbar switches is proposed and examined. Buffered switch technique is well known to solve the data collision problem of the switch networks. The characteristic of a network with crossbar switches is determined by both the connection pattern of the switches and the limitation of data flow in a each switch. In this thesis, the evaluation models of three different networks : Multistage interconnection network, Fat-tree network, and other ordinary communication network are developed. The proposed evaluation model is developed by investigating the transfer patterns of data packets in a switch with output-buffers. Two important parameters of the network performance, throughput and delay, are evaluated. The proposed model takes simple and primitive switch networks, i.e., no flow control and drop packet, to demonstrate analysis procedures clearly. It, however, can not only be applied to any other complicate modern switch networks that have intelligent flow control but also estimate the performance of any size networks with multiple-buffered switches. To validate the proposed analysis model, the simulation is carried out on the various sizes of networks that uses the multiple buffered crossbar switches. It is shown that both the analysis and the simulation results match closely. It is also observed that the increasing rate of Normalized Throughput is reduced and the Network Delay is getting bigger as the buffer size increased.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.8 no.3
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• pp.577-585
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• 2004

System Packet Interface Level 4 Phase(SPI-4.2) is an interface for packet and cell transfer between a physical layer(PHY) device and a link layer device, for aggregate bandwidths of OC-192 ATM and Packet Over Sonet/SDH(POS), as well as 10Gbps Ethernet applications. In this paper, we performs the research for SPI-4.2. Also we analyze the performance of SPI-4.2 interface module after modeling using C programming language. This paper shows that SPI-4.2 interface module with 512-word FIFO depth is able to be adapted for the offered loads to 97％ in random uniform traffic and 94％ in bursty traffic with bursty length 32. SPI-4.2 interface module can experience an performance degradation due to heavy overhead when it massively receives small size packets less than 14-byte. SPI-4.2 interface module is suited for line cards in gigabit/terabit routers, and optical cross-connect switches, and SONET/SDH-based transmission systems.

• Korean Management Science Review
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• v.10 no.1
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• pp.139-156
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• 1993

Various ATM switches have been proposed since Asynchronous Transfer Mode (ATM) was recognized as appropriate for implementing broadband integrated services digital network (BISDN). An ATM switching network may be evaluated on two sides : traffic performances (maximum throughput, delay, and packet loss probability, etc.) and structural features (complexity, i.e. the number of switch elements necessary to construct the same size switching network, maintenance, modularity, and fault tolerance, etc.). ATM switching networks proposed to date tend to show the contrary characteristics between structural features and traffic performance. The Knockout Switch, which is well known as one of ATM switches, shows a good traffic performance but it needs so many switch elements and buffers. In this paper, we propose an input and output buffered Knockout Switch for the purpose of reducing the number of switch elements and buffers of the existing Knockout Switch. We analyze the traffic performance and the structural features of the proposed switching architecture through a discrete time Markov chain and compare with those of the existing Knockout Switch. It was found that the proposed architecture could reduce more than 40 percent of switch elements and more than 30 percent of buffers under a given requirement of cell loss probability of the switch.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.3
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• pp.762-777
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• 2014

With the increasing usage of cloud applications such as MapReduce and social networking, the amount of data traffic in data center networks continues to grow. Moreover, these appli-cations follow the incast traffic pattern, where a large burst of traffic sent by a number of senders, accumulates simultaneously at the shallow-buffered data center switches. This causes severe packet losses. The currently deployed TCP is custom-tailored for the wide-area Internet. This causes cloud applications to suffer long completion times towing to the packet losses, and hence, results in a poor quality of service. An Explicit Congestion Notification (ECN)-based approach is an attractive solution that conservatively adjusts to the network congestion in advance. This legacy approach, however, lacks scalability in terms of the number of flows. In this paper, we reveal the primary cause of the scalability issue through analysis, and propose a new congestion-control algorithm called FaST. FaST employs a novel, virtual congestion window to conduct fine-grained congestion control that results in improved scalability. Fur-thermore, FaST is easy to deploy since it requires only a few software modifications at the server-side. Through ns-3 simulations, we show that FaST improves the scalability of data center networks compared with the existing approaches.

• Electronics and Telecommunications Trends
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• v.35 no.6
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• pp.68-77
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• 2020

Along the advancement of mobile networks, fixed telephone networks are gradually advancing from legacy networks based on copper and circuit-switches to optical cables and packet-switched IP networks. Incumbent fixed-line telephone operators are facilitating the introduction of IP networks and are gradually converting to IP-based facilities according to the investment plans for each operator. As the PSTN's IP conversion exceeds a certain level and VoIP; (an alternative service); is activated, some countries; such as Europe; are considering terminating the PSTN service, centering on operators. In this paper, trends in the procedure, timing, and major issues related to the termination of an overseas PSTN are examined. The domestic status is also examined.

• Proceedings of the IEEK Conference
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• 2001.06c
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• pp.199-202
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• 2001

In this paper, we proposed and analyzed a new class of irregular fault-tolerant multistage interconnection network named as Extended-QT(Quad Tree) network. E-QT network is extended QT network. A unique path MIN usually is low hardware complexity and control algorithm. So we proposes a class of multipath MIN which are obtained by adding self-loop auxiliary links at the a1l stages in QT(Quad Tree) networks so that they can provide more paths between each source-destination pair. The routing of proposed structure is adaptived and is based by a routing tag. Starting with the routing tag for the minimum path between a given source-destination pair, routing algorithm uses a set of rules to select switches and modify routing tag. Trying the self-loop auxiliary link when both of the output links are unavailable. If the trying is failure, the packet discard. In simulation, an index of performance called reliability and cost are introduced to compare different kinds of MINs. As a result, the prouosed MINs have better capacity than 07 networks.

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.113-118
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• 2005

Softswitch is the core BcN equipment which voice and multimedia switching based on the IP Technologies. It is designed to replace the Class 5(local Exchange) and Class 4(Toll Exchange) switch based on the circuit wired and wireless switching network technologies. Softswitch gets its name because typically it is a software based solution implemented on general purpose computers/servers. While the traditional PSTN switches are rely on dedicated facilities for T and S inter-connection and are designed primarily for voice communications. Packet based Softswitch is divided the control of call and bearer, very different from Public telephone network. Sometimes Call Agent or Media Gateway Controller, a key component in the VoIP solution, is also called Softswitch. This paper will suggest the software architecture of softswitch for performance in call processing part, also suggest the session management model to cover call setup latency.

• ETRI Journal
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• v.40 no.3
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• pp.337-346
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• 2018

In this paper, we propose a grant-aware (GA) scheduling algorithm that can provide higher throughput and lower latency than a conventional dual round-robin matching (DRRM) method. In our proposed GA algorithm, when an output receives requests from different inputs, the output not only sends a grant to the selected input, but also sends a grant indicator to all the other inputs to share the grant information. This allows the inputs to skip the granted outputs in their input arbiters in the next iteration. Simulation results using OPNET show that the proposed algorithm provides a maximum 3% higher throughput with approximately 31% less queuing delay than DRRM.