• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.1B
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• pp.41-51
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• 2004

Operation and maintenance (OAM) in optical burst switching (OBS) networks has not yet been addressed even though OBS has been gaining research interest in recent years. In this paper, we defined five OBS functions such as Burst Termination (BT), Burst Transmission (BTX), Burst Switching (BSW), Routing and Switching Control (RSC), and Protection and Restoration (PAR). A functional model for OBS networks and an OAM architecture are designed to meet the operational requirements. We present the first framework to realize OAM in OBS networks, including OAM activities, OAM-capable OBS nodes such as ingress edge, core, and egress edge nodes, OAM information and communication models and protocols. A number of examples of possible network failures are pointed out and the corresponding reactions to these using the proposed OAM architecture are presented.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.40 no.10
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• pp.43-50
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• 2003

This paper describes the optical resource reservation protocol for Optical Burst Switching(OBS) networks, in which the burst sending time and the burst size at an ingress node are determined by the available resources between the ingress and egress nodes. Our scheme attempts to improve the burst contention resolution and optical channel utilization. We analyze the performance of the optical resource reservation protocol by using NS2 simulator.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.40 no.10
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• pp.16-23
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• 2003

In this paper, we propose a new optical hybrid switching system that takes advantage of both Optical Burst Switching (OBS) and Optical Circuit Switching (OCS) technologies. This system classifies incoming IP traffic flows into short-lived and long-lived flows for hybrid switching. For performance analysis, we model the system as a single server queue in a Markovian environment. The burst generation process is assumed to follow a two-state Markov Modulated Poisson Process (MMPP), and the service rate fluctuates based on the number of concurrent OCS sessions. Results of the mean delay and queue size for OBS bursts are derived.

• ETRI Journal
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• v.24 no.4
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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.

• The KIPS Transactions:PartC
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• v.12C no.6 s.102
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• pp.927-932
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• 2005

We investigate the effects on performance of using a partial retransmission mechanism in Optical Burst Switched(OBS) networks. In our scheme, the lost segments of a burst are retransmitted in the OBS layer. We also propose an optical resource reservation using the partial retransmission mechanism. Our scheme attempts to improve the burst contention resolution and optical channel utilization. The performance of the proposed mechanism is analyzed by NS2 simulations. Simulation results indicate that link utilization of the OBS network is improved makedly at the expense of signaling and ingress buffers.

• Proceedings of the IEEK Conference
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• 2000.11a
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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.

• Convergence Security Journal
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• v.5 no.1
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• pp.45-52
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• 2005

In this paper, the development specification of the optical burst switching system (OBS) for next generation internet services is presented. The development specification includes the number of input/output nodes, the number of wavelengths, buffer capacity, the capacity/queue size of the controller and maximum burst assembly delay. From the performance parameters related to the OBS design, an mathematical model to maximize the throughput and minimize the data loss is presented, and then efficient heuristic algorithm is also presented to analyze the sensitivity of the system parameters.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.40 no.10
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• pp.59-66
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• 2003

We propose the novel optical burst switching scheme to guarantee a minimum bandwidth for multiple classes. To date, QoS studies on OBS network are capable of differentiating two classes, but have difficulties in providing a minimum bandwidth lot several classes because of lower classes' collision with the highest class bursts in the networks. To solve that problem, in our proposed scheme we assign time zones in a data channel for each class periodically, making one burst have top priority at least its zone. Also, the new burst assembling algorithm, as well as the way of managing data channel, is necessarily proposed to coordinate with the proposed OBS scheme. Through the evaluation, we show that the worst-case end-to-end delay is small enough and the received bandwidth of the lower classes is still assured regardless of the traffic load of the highest class.

• Proceedings of the IEEK Conference
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• 2004.06a
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• pp.241-244
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• 2004

In recent years, WDM networks have received much attention as the Internet backbone networks because of the explosive growth of the Internet IP-based traffic. The Optical Burst Switching (OBS) has been proposed as an effective optical switching technology in the WDM networks. OBS has the advantages in 1) the high usage rate of the bandwidth, and 2) no necessity of optical buffer. However OBS has the burst-contention problem in the networks. The deflection routing is proposed as one of means to solve this problem. In this paper, we propose a new routing method of using deflection routing. In addition. we propose a QoS/CoS control method using a new routing algorithm. Finally, we show the variety of the proposed methods by computer simulations.

• The KIPS Transactions:PartC
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• v.13C no.4 s.107
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• pp.441-446
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• 2006

In recent years, WDM networks have received much attention as the Internet backbone networks because of the explosive growth of the Internet IP-based traffic. The Optical Burst Switching (OBS) has been proposed as an effective optical switching technology in the WDM networks. The OBS has the advantages in 1) the high usage rate of the bandwidth, and 2) no necessity of optical buffer. However, the OBS has the burst-contention problem in the networks. The deflection routing is proposed as one of means to solve this problem. In this paper, we propose a new routing method to minimize burst loss in the deflection routing based networks. In addition, we propose a QoS control method using a new routing algorithm. Finally, we show the variety of the proposed methods by computer simulations.