• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.3B
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• pp.72-84
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• 2005

Optical burst switching networks usually employ one-way reservation by sending a burst control packet with a specific offset time, before transmitting each data burst Same. Due to such a Property, burst-contentions occur when multiple bursts contend for the same wavelength in the same output link simultaneously in a node, leading to burst losses, eventually degrading the quality of service. Therefore, in this paper, we propose a dynamic routing algorithm using minimum local state information in order to decrease burst-contentions. In this proposed scheme, if burst loss rate exceeds a threshold value at a certain node, a new alternative routing path is chosen according to burst priority and location of burst generation, which enables the contending bursts to detour around the congested link. Moreover, for reducing the effect of sending bursts on the primary path due to the alternative path, we also apply a minimum path-cost based routing on link-cost concept. Our simulation results show that proposed scheme improves the network performance in terms of burst loss probability and throughput by comparing with conventional one.

• Convergence Security Journal
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• v.13 no.3
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• pp.25-31
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• 2013

Looking at the recent value change of users and the usage pattern of network users, it is changing from simple web information, one-way information acquisition and data transmission to increase of usage of multimedia, increasing demand for security and customization, and increasing demands for free mobility. Due to this change of demand, the services which were provided individually, developed into a form which is merged, the network also seems to develop into the combined network from the individual network for individual service, and the communication network control technology which is the core technology is also rapidly developing. To reflect the users' demands, the next generation network created the multi-layer network which is based on the WDM/IP transmission system and added the to make it easy to restructure. P-OTS (Packet-Optical Transport System) can be defined as a platform that combines SONET/SDH, Ethernet, DWDM, optical transport network (OTN) switching and reconfigurable optical add-drop multiplexers (ROADMs). In this paper, we suggested that the optimum path choice be performed through diversification of the PCE-based path selection using the information of various layers altogether in the multi-layer environment, compared with the established path selection method when the path was selected using the information of each layers.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.19 no.1
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• pp.159-169
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• 1994

A multichannel optical slotted ring network is designed using a wavelength division multiplexing(WDM) technique and photonic packet switching devices. The electronics speed bottleneck is removed out of the ring, which allows utilization of the full bandwidth for the optical fiber transmission medium. The ring channel adopts a slotted ring concept with a destination cell remove strategy for the eing access mechanism. The slot size in the ring is selected as the same as that of ATM based cell in order to be used as B-ISDN Access Networks. In this paper, we devised a mathematical method to measure the average transfer delay characteristics of the network. The analytical method turned out to yield accurate results over a broad range of parameters in comparison to simulation results. From the study, we observed the average transfer delay of the network as the network parameters vary.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.6B
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• pp.331-337
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• 2005

The optical Internet is considered as a feasible solution for transporting huge amount of traffic volume in the future Internet. Among optical switching technology for the optical Internet, OBS becomes one of the most promoting solution. Recently, a lebeled OBS(LOBS) architecture is considered for an efficient control on OBS network. Given that a data burst may contain few thousands of IP packets, a single loss of data burst results in a serious throughput degradation in LOBS network. In this paper, we improve the performance of LOBS network by introducing the burst congestion control mechanism. More specifically, the OBS router at the network core detects the network congestion by measuring the loss probability of burst control packet. The OBS router at the network edge reduces the burst generation according to the network condition repored by the OBS router at the network core. Through the simulations, it is shown that the proposed congestion control mechanism can reduce the burst loss probability and improve the LOBS network throughput.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.10A
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• pp.912-921
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• 2005

Optical burst switching(OBS) is a promising solution for building terabit optical routers and realizing If over WDM. Channel scheduling Algorithm for reduce contention is one of the major challenges in OBS. We address the issue of how to provide basic burst channel scheduling in optical burst switched WDM networks with fiber delay lines(FDLs). In OBS networks the control and payload components or a burst are sent separately with a time gap. If CHP arrives to burst switch node, because using scheduling algorithm for data burst, reservation resources such as wavelength and transmit data burst without O/E/O conversion, because contention and void between burst are happened at channel scheduling process for data burst that happened the link utilization and bust drop probability Existent proposed methods are become much research to solve these problems. Propose channel scheduling algorithm that use Release Time of bust to emphasize clearance between data and data dissipation that is happened in data assignment in this treatise and maximize bust drop probability and the resources use rate (RTUC : Release Time Unscheduled Channel). As simulation results, Confirmed that is more superior in terms of data drop and link utilization than scheduling algorithm that is proposed existing. As simulation results, confirmed improved performance than scheduling algorithm that is proposed existing in terms of survival of burst, efficiency resource and delay. However, In case load were less, degradation confirmed than existent scheduling algorithm relatively, and confirmed that is superior in data drop aspect in case of load increased.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.44 no.12
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• pp.63-72
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• 2007

This paper addresses the system development that can transfer data and TDM signals simultaneously by adding TDM pseudowires functions to E-PON system. E-PON technology is one of many technologies which can realize FTTH, has raised as next generation access network solution having both low-cost Ethernet technology and optical infrastructure. TDM pseudowires service is the new voice/data conversion technology which can transfer the existing TDM circuit switched voice and data over packet switching network. In this paper, this system can provide both data and TDM service without deteriorating QoS by adding TDM pseudowires service module to E-PON, and then implementing QoS control function. Therefore, the competitive system which can transfer both data and TDM signal, can be installed.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.9B
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• pp.793-805
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• 2003

In OBS (Optical Burst Switching) networks which decouple the burst from its header, the fault of a fiber link can lead to the failure of all the light-path that traverses the fiber. Because each light-path is expected to operate at a rate of a few Gbps by using WDM (Wavelength Division Multiplexing) technology, any failure may lead to large data loss. Therefore, an efficient recovery scheme must be provided. In this paper, we analyze network utilization and BCP (Burst Control Packet) loss rate according to each link failure by applying the conventional restoration schemes in OBS networks. And through these simulation results, an ASPR scheme is proposed improve the fault management scheme in terms of recovery time and throughput. Finally, We compare the performance of our proposed scheme with that of the conventional one with respect to burst loss rate, resource utilization and throughput by OPNET simulations.