• ETRI Journal
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• 제34권6호
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• pp.816-826
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• 2012

Self-healing Ethernet rings show promise for realizing the SONET/SDH-grade resilience in Carrier Ethernet infrastructures. However, when a ring is faulty, high-priority protection messages are processed in less time than low-priority data frames are processed. In this situation, any delayed data frames either being queued or traveling through long ring spans will cause the ring nodes to generate incorrect forwarding information. As a result, the data frames spread in the wrong direction, causing the ring to become unstable. To solve this problem, we propose four schemes, that is, dual flush, flush delay timer setting, purge triggering, and priority setting, and evaluate their protection performance under various traffic conditions on a ring based on the Ethernet ring protection (ERP) method. In addition, we develop an absorbing Markov chain model of the ERP protocol to observe how traffic congestion can impact the protection performance of the proposed priority setting scheme. Based on our observations, we propose a more reliable priority setting scheme, which guarantees faultless protection, even in a congested ring.

• ETRI Journal
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• 제32권2호
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• pp.184-194
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• 2010

Ethernet ring protection (ERP) technology, which is defined in ITU-T Recommendation G.8032, has been developed to provide carrier grade recovery for Ethernet ring networks. However, the filtering database (FDB) flush method adopted in the current ERP standard has the drawback of introducing a large amount of transient traffic overshoot caused by flooded Ethernet frames right after protection switching. This traffic overshooting is especially critical when a ring provides services to a large number of clients. According to our experimental results, the traditional FDB flush requires a link capacity about sixteen times greater than the steady state traffic bandwidth. This paper introduces four flush optimization schemes to resolve this issue and investigates how the proposed schemes deal with the transient traffic overshoot on a multi-ring network under failure conditions. With a network simulator, we evaluate the performance of the proposed schemes and compare them to the conventional FDB flush scheme. Among the proposed methods, the extended FDB advertisement method shows the fastest and most stable protection switching performance.

• 한국통신학회논문지
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• 제27권10C호
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• pp.933-936
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• 2002

인터넷 사용의 급증으로 말미암아 패킷을 효과적으로 처리할 수 있는 이더넷 장비의 용량도 빠른 속도로 증가하고 있다. 한편 이더넷의 용량이 증가함에 따라 장치의 고신뢰성이 요구되고 있다. 본 논문에서는 현재 메트로 영역에서 사용되는 장치들에 적용 가능한 광링크 보호절체 방식을 제시하고 실험 결과를 보였다.

• Journal of information and communication convergence engineering
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• 제1권1호
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• pp.6-11
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• 2003

In general, standard TCP/IP (transmission control protocol-internet protocol), which is called TCP/IP, is using as the communication basis protocol between any collections of networks that is connected. In this paper, using this TCP/IP implementation of remote control system and suitable program for long distance communication is proposed. This system can make system, which basic Ethernet and TCP/IP used system, to mini modeling, so all module that is using here can be used. Therefore, intention of this paper is to reduce expenses, to effective manage for plant and to increase of productivity as linking each plant of several factory to TCP/IP and Ethernet, and then many control plant and manager minimize the needed course.

• 대한임베디드공학회논문지
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• 제16권6호
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• pp.247-251
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• 2021

We propose a protocol for Ethernet-based industrial real-time communication networks. In the protocol, the master periodically transmits control frames to all slaves, and the ring-type network topology is selected to achieve high-speed transmission speed. The proposed protocol is implemented in the form of both firmware and Linux kernel modules. To improve the transmission speed, the MAC address table is disabled in the firmware implementation, and the NAPI function of the Ethernet driver is removed in the Linux kernel module implementation. A network experiment environment is built with four ARM processor-based embedded systems and network operation experiments are performed for various frame sizes. From the experimental results, it is verified that the proposed protocol normally operates, and the firmware implementation shows better transmission speed than the Linux kernel module implementation.

• 한국통신학회논문지
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• 제32권1B호
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• pp.53-60
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• 2007

본 연구에서는 Diffserv 기반의 네트워크, 특히 그 중에서도 트리구조를 가지는 네트워크에서의 지연시간에 대해서 연구하였다. 이러한 네트워크에서의 지연시간 최대치를 구하는 수식을 구하였고, 특히 기존에 알려진 바와는 달리 트리구조의 네트워크에서는 네트워크 utilization과는 상관없이 최대치가 항상 존재함을 보였다. 지연시간 최대치의 특성은 다음과 같이 표현된다. 네트워크 utilization이 큰 경우 네트워크내의 최대 hop count의 제곱에 비례하며, 네트워크 utilization이 작은 경우는 최대 hop count에 비례한다. 이러한 결과를 바탕으로 실제 Metro Ethernet Network과 같은 대규모 네트워크의 경우에서 DiffServ를 이용하여 실시간 트래픽 전송이 가능하다는 것을 보였다.

• 전기전자학회논문지
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• 제7권2호
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• pp.265-270
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• 2003

본 논문에서는 웹 서버의 부하 분산을 위해 네트워크를 LAN 내부와 LAN 외부로 나누고 이들에 각각의 웹 서버를 할당한다. LAN 내부의 노드들에 의한 접속만이 가능한 웹 서버의 성능은 RTO(Retransmission Time Out : 재전송타임아웃)라는 TCP 파라미터에 의해 많은 영향을 받는다. 웹 서버의 운영체제 내에 디폴트로 설정된 RTO 값은 LAN에서는 지나치게 큰 값으로 네트워크와 웹 서버의 성능을 저하시킨다. 이에 본 논문에서는 기존의 재전송 타임아웃의 알고리즘 방식을 이용하지 않고, 조정된 RTO값을 사용하여 LAN 내부의 웹 서버 성능을 향상시킬 수 있음을 확인하였다.

• 정보와 통신
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• 제33권1호
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• pp.49-53
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• 2015

본고에서는 4G/5G/WiFi 무선 통신의 C-RAN(Centralized/Cloud Radio Access Network)을 지원하는 xhaul망에서의 이더넷 응용 기술에 대해 분석한다. xhaul에서의 요구사항을 고찰하고, 이를 충족시키기 위한 이더넷 응용으로서 RoE(Radio over Ethernet)을 중심으로 한 기술 분석과 함께, 그 외 프론트홀 전송 기술을 알아봄으로써, xhaul에서의 이더넷의 응용과 더불어 기타 차세대 무선 망 기술과 함께 유무선 융합 전송 기술에 대한 방향을 타진해 보도록 한다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2006년도 제37회 하계학술대회 논문집 A
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• pp.70-71
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• 2006

IEC61850 which has comes to international standard for substation automation is designed with a station and process bus communication with Ethernet. In this paper, mentioning difference between official networks and substation networks, authors present the requirements for temperature, humidity and EMI characteristics. The properties which network switch should be satisfied and the technologies which make those requirements possible are also proposed. Additionally, we analysis the traffic pattern of communication services which IEC61850 supports. Based on the pattern, we propose a practical design example of IEC61850 based network for a 154kV substation.

• ETRI Journal
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• 제27권6호
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• pp.802-805
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• 2005

A dynamic bandwidth allocation (DBA) scheme, an inter -optical network unit (ONU) bandwidth scheduling, is presented to provide quality of service (QoS) to different classes of packets in Ethernet passive optical networks (EPONs). This scheme, referred to as TADBA, is based on efficient threshold reporting from, and adaptive polling order rearranging of, ONUs. It has been shown that the network resources are efficiently allocated among the three traffic classes by guaranteeing the requested QoS, adaptively rearranging the polling orders, and avoiding nearly all fragmentation losses. Simulation results using an OPNET network simulator show that TADBA performs well in comparison to the available allocation scheme for the given parameters, such as packet delay and channel utilization.