• 한국통신학회논문지
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• 제29권1B호
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• pp.41-51
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• 2004

OBS (Optical Burst Switching) 네트워크에 관한 연구가 최근 활발히 진행되고 있으나 OBS 네트워크 운용에 필수적인 OAM (Operation md Maintenance)에 대한 연구는 아직 다루어지고 있지 않다. 본 논문에서는 다섯가지 OBS 기능들, 즉 BT (Burst Termination), BTX (Burst Transmission), BSW (Burst Switching), RSC(Routing and Switching Control), 그리고 PAR (Protection and Restoration)을 정의하였고, 이 기능적 모델에 근거하여 네트워크 운용 요구 조건들을 만족시키기 위한 OAM 아키텍처를 설계하였다. 또한, OAM 수행에 필요한 OAM 동작들의 정의와 OAM이 가능한 ingress 에지, 코어, egress 에지 노드들의 구조, 그리고 OAM 정보 및 통신 모델과 프로토콜 등과 같은 OAM 구현을 위한 기본 체제를 제안하였다. 그리고, 제안된 OAM 아키텍처를 이용하여 OBS 네트워크에서 발생 가능한 여러 가지 장애들에 대한 OAM을 정리하였다.

• 대한산업공학회지
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• 제28권2호
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• pp.139-146
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• 2002

The third generation mobile communication needs to provide multimedia service with increased data rates. Thus an efficient allocation of radio and network resources is very important. This paper models the 'burst switching' as an efficient radio resource allocation scheme and the performance is compared to the circuit and packet switching. In burst switching, radio resource is allocated to a call for the duration of data bursts rather than an entire session or a single packet as in the case of circuit and packet switching. After a stream of data burst, if a packet does not arrive during timer2 value ($\tau_{2}$), the channel of physical layer is released and the call stays in suspended state. Again if a packet does not arrive for timerl value ($\tau_{1}$) in the suspended state, the upper layer is also released. Thus the two timer values to minimize the sum of access delay and queuing delay need to be determined. In this paper, we focus on the decision of $\tau_{2}$ which minimizes the access and queueing delay with the assumption that traffic arrivals follow Poison process. The simulation, however, is performed with Pareto distribution which well describes the bursty traffic. The computational results show that the delay and the packet loss probability by the burst switching is dramatically reduced compared to the packet switching.

• ETRI Journal
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• 제30권1호
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• pp.164-166
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• 2008

This paper proposes a priority-based duplicate burst transmission mechanism in an optical burst switching network to enhance the probability of successful reception of bursts. The performance of the proposed mechanism is evaluated by NS2 simulations. Our results show that the burst loss rate is improved especially under light traffic loads.

• ETRI Journal
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• 제24권4호
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• pp.311-322
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• 2002

Presently, optical burst switching (OBS) technology is under study as a promising solution for the backbone of the optical Internet in the near future because OBS eliminates the optical buffer problem at the switching node with the help of no optical/electro/optical conversion and guarantees class of service without any buffering. To implement the OBS network, there are a lot of challenging issues to be solved. The edge router, burst offset time management, and burst assembly mechanism are critical issues. In addition, the core router needs data burst and control header packet scheduling, a protection and restoration mechanism, and a contention resolution scheme. In this paper, we focus on the burst assembly mechanism. We present a novel data burst generation algorithm that uses hysteresis characteristics in the queueing model for the ingress edge node in optical burst switching networks. Simulation with Poisson and self-similar traffic models shows that this algorithm adaptively changes the data burst size according to the offered load and offers high average data burst utilization with a lower timer operation. It also reduces the possibility of a continuous blocking problem in the bandwidth reservation request, limits the maximum queueing delay, and minimizes the required burst size by lifting up data burst utilization for bursty input IP traffic.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 추계종합학술대회 논문집(1)
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• pp.177-180
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• 2000

Optical burst switching(OBS) is a new switching paradigm to supporting bursty traffic on the Internet efficiently. OBS separates burst level and control level. To handle data burst efficiently, the scheduling schemes in optical burst switching systems must keep track of future resource availability when assigning arriving data bursts to wavelength channels. In this paper, we evaluate the performance of three scheduling schemes which are called Horizon, Single-gap and Multiple-gap, as a basic study for the future research of Optical Internet. Thus, firstly, we analyze the trade-off between the performance and the processing overhead of each scheme. In addition, the performance of OBS system which uses Multiple-gap scheduling is evaluated in detail under various network size. We use simulation for performance evaluation in terms of burst loss rate(BLR), wavelength channel utilization and the number of management data.

• 한국멀티미디어학회논문지
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• 제16권9호
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• pp.1067-1076
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• 2013

Known as an important criterion that evaluates performance of future high-speed backbone networks, burst data loss ratio is well-studied in Optical Burst Switching networks. Current literatures mostly focus on reduce burst loss ratio without considering the system stability and link utilization after reducing. In this paper, we propose a novel framework which comes from feedback theoretic to dynamically control burst loss ratio in OBS. The proposed scheme tries to track the pre-set values of burst loss ratio and increases the stability and link utilization degree. The simulation results show that measured burst loss ratio always tracks setup reference with small errors, wavelength channel utilization is increased up to 2% and the system stability is also improved.

• ETRI Journal
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• 제44권2호
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• pp.274-285
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• 2022

Retransmission in optical burst switching networks is a solution to recover data loss by retransmitting the dropped burst. The ingress node temporarily stores a copy of the complete burst and sends it each time it receives a retransmission request from the core node. Some retransmission schemes have been suggested, but uncontrolled retransmission often increases the network load, consumes more bandwidth, and consequently, increases the probability of contention. Controlled retransmission is therefore essential. This paper proposes a new controlled retransmission scheme for loss recovery, where the available bandwidth of wavelength channels and the burst lifetime are referred to as network conditions to determine whether to transmit a dropped burst. A retrial queue-based analysis model is also constructed to validate the proposed retransmission scheme. The simulation and analysis results show that the controlled retransmission scheme is more efficient than the previously suggested schemes regarding byte loss probability, successful retransmission rate, and network throughput.

• 한국통신학회논문지
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• 제30권3A호
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• pp.178-183
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• 2005

광 버스트 교환 망에서 contention으로 인한 버스트의 손실은 망 성능에 중요한 영향을 끼친다. 많은 contention resolution 방식들이 제안되었지만 이들 중의 대부분은 contention을 방지하기 보다는 주로 수동적인 형태로 contention을 해결하는데 주력하고 있다. 본 논문에서는 망 내 트래픽 부하와 버스트 손실에 따라 버스트의 전송률을 제어하는 능동적인 contention avoidance 방식을 제안한다. 제안한 방식이, 기존의 광 버스트 전송률 제어 방식 및 버스트 전송률 제어를 제공하지 않는 일반적인 광 버스트 교환 모델과 비교하여 버스트 손실률이 향상됨과 동시에 처리율(throughput)도 보장함을, 시뮬레이션을 통해 입증한다.

• 대한전자공학회논문지TC
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• 제40권10호
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• pp.16-23
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• 2003

본 논문에서 광 네트워크에서 광 버스트 스위칭(Optical Burst Switching, OBS)과 광 회선 스위칭 (Optical Circuit Switching, OCS) 기술의 장점을 동시에 가지는 새로운 광 hybrid 스위칭(Optical Hybrid Switching) 시스템을 제안한다. 이 시스템은 들어오는 IP 트래픽을 hybrid 스위칭을 위해 짧은(short-lived) 흐름과 긴(long-lived) 흐름 구분한다. 성능 분석을 위하여 시스템을 Markovian 환경에서 단일 서버 큐로서 모델링 한다. 버스트 생성 프로세스는 two-state Markov Modulated Poisson Process (MMPP)를 따른다고 가정하고 서비스 율은 동시에 발생하는 OCS 세션의 수에 따라 변한다. OBS 버스트에 대한 평균 지연 및 큐 사이즈의 결과를 보인다.

• 융합보안논문지
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• 제5권1호
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• pp.45-52
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• 2005

본 논문에서는 차세대 인터넷 서비스를 지원하기 위한 광버스트 교환 시스템(Optical Burst Switching System : OBS)의 개발 규격을 제시한다. 개발 규격이란 입출력 노드의 수, 파장의 수, 버퍼의 용량, 컨트롤러의 용량/큐 크기 및 최대 버스트 조립 지연시간을 포함한다. 개발 규격을 제시하기 위하여 관련된 성능 파라메터를 추출하고 시스템의 성능을 최대화하며 가입자의 데이터 손실율을 최소화하는 수학적 모형을 제시하고 효율적인 휴리스틱 알고리즘을 제시한다. 그리고 여러 성능 파라메타들에 대한 시스템의 민감도를 분석한다.