• IE interfaces
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• v.9 no.3
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• pp.52-63
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• 1996

DCS(Digital Cross-connect System)를 이용한 다이나믹 자체 치유 알로리즘들은 주로 대상을 하나의 링크 장애에 대해서 완전 복구될 수 있는 예비 용량을 갖는 망을 대상으로 복구 시간을 줄이는 방향들이 제시되어 왔으나, 이러한 고장난 망의 복구를 위한 자체 치유 복구 알고리즘의 효율성은 이중 장애나 노드 장애에 적용 되었을 때의 복구율을 가지고 평가가 된다. 본 논문에서는 단일 링크(single link) 장애뿐만 아니라 이중 링크(double link) 장애에 대해서도 망의 복구 허용시간 내에서 복구율을 높이는 새로운 망복루 알로리즘을 제안한다. 이를 위해서 망의 복구 허용 시간 내에, 전체적인 예비 용량을 고려하여 선택된 복구 경로의 각 링크의 부하를 균등하게 하는 복구 방법을 적용한다. 또한 제안된 알고리즘의 시뮬레이션 결가를 기본의 복구 방법과 비교 분석한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.12
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• pp.2744-2754
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• 1997

Recently, the Multi-Layer Restoration(MLR) algorithm was proposed by British Telecom(BT) to restore the network failures in Digital Cross-connect System(DCS) mesh survival network[1, 2]. This algorithm has multi restoration stage which is composed of the pre-planned and dynamic restoration. This algorithm is effective its ability in link or node failures. This reason is that it does not restore in the pre-planned rstoration stage but in dynamic restoration stage. In this paper, we propose the MLR with pre-planned Multi-Chooser(PMC) and successive restoration ratio algorithm. This proposed algorithm has a excellent performance for restortion time and ratio, spare channel availability and fast restoration from multiple link failure or node failure. This paper proposed the modeling and restoration algorithm, and analyzed the performance of the algorithm by simulation using OPNET(OPtimized Network Engineering Tools).

• The KIPS Transactions:PartA
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• v.16A no.1
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• pp.17-26
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• 2009

Large-scale wireless sensor network are expected to play an increasingly important role for the data collection in harmful area. However, the physical fragility of sensor node makes reliable routing in harmful area a challenging problem. Since several sensor nodes in harmful area could be damaged all at once, the network should have the availability to recover routing from node failures in large area. Many routing protocols take accounts of failure recovery of single node but it is very hard these protocols to recover routing from large scale failures. In this paper, we propose a routing protocol, which we refer to as LSFA, to recover network fast from failures in large area. LSFA detects the failure by counting the packet loss from parent node and in case of failure detection LSFAdecreases the routing interval to notify the failure to the neighbor nodes. Our experimental results indicate clearly that LSFA could recover large area failures fast with less packets than previous protocols.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.26 no.9A
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• pp.1542-1552
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• 2001

MPLS 망에서 설정된 LSP (Label Switched Path)내에 링크/노드 장애나 혼잡이 발생한 트래픽을 대체 경로로 우회시킴으로써 신뢰성 있는 서비스를 제공하는 것은 필수적이다. 기존에 제안된 기법들은 장애가 발생하기 전에 대체 경로를 미리 설정하기 때문에 빠른 장애 복구를 제공할 수 있지만 자원 낭비가 심하며 기본 LSP와 대체 LSP가 모두 장애인 경우에는 대처할 수가 없는 문제점을 가지고 있다. 본 논문에서는 장애를 탐지한 노드가 기본 경로상에 존재할 수 있는 가능한 모든 대체 경로 중에서 비용이 최소인 대체 경로를 계산한 후에 그 경로를 따라서 대체 LSP를 설정하는 동적 복구 기법을 제안한다. 제안된 기법은 최소 비용인 대체 경로를 계산하기 위하여 제안된 알고리즘을 사용함으로써 비교적 빠른 시간 내에 대체 LSP를 설정할 수 있으며, 자원 효율성이 높고, 기본경로와 대체 경로가 장애인 경우에도 대처할 수 있다. 제안된 기법의 성능을 평가하기 위하여 링크 장애, 노드 장애, 대체 경로 장애, 그리고 동시 발생 장애에 대하여 각각 시뮬레이션 하였다. 실험 결과, 제안된 기법은 기존의 기법들과 비교해서 동시 발생 장애에서는 성능이 좋지 않았지만, 링크 장애와 노드 장애의 경우에 비교적 성능이 좋았고, 기본 경로와 대체 경로가 장애인 경우에도 복구할 수 있었으며 자원 효율성에서는 월등히 우수했다.

• The Transactions of the Korea Information Processing Society
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• v.7 no.8
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• pp.2497-2504
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• 2000

This paper is aimed at defining items of fault, and then constructing rules of fault diagnosis and recovery using INBANCA technology for the purpose of managing the weh server. The fault items of web server consist of the process fault, server overload, network interface fault, configuration and performance fault. Based on these items, the actual fault management is carried out fault referencing. In order to reference the fault, we have formulated the system-level fault diagnosis production rule and the service-level fault diagnosis rule, conjunction with translating management knowledge into active network. Also, adaptive recovery mechanism of web server is applied to defining recovery rule and constructing case library for case-based web server fault recovery. Finally, through the experiment, fault environment and applicability of each proposed production rule and recovering scheme are presented to verify justification of proposed diagnosis rules and recovery mechanism for fault management. An intelligent case-based fault management scheme proposed in this paper can minimize an effort of web master to remove fault incurred web administration and operation.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.40 no.7
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• pp.507-517
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• 2003

A single fiber failure in mesh-based WDM networks may result in the loss of a large number of data. To remedy this problem, an efficient restoration algorithm for a single fiber failure in the mesh- based WDM network is necessary. We propose a new algorithm for restoration scheme in WDM networks and compare it with previous schemes. Path restoration and link restoration are two representative restoration schemes which deal with only a single link failure. In this paper, we propose two kinds of efficient restoration scheme. In the proposed schemes the restoration path for each link failure is not secured. The mesh network is decomposed into a number of small loops. In one algorithm, any link failure in a certain loop is regarded as the failure of the loop and the restoration lightpath is selected by detouring the failed loop. In another scheme any link failure in a certain loop is restored within the loop. We compare performance of the proposed schemes with conventional path restoration scheme and link restoration scheme. Simulation results show that CPU time in the proposed schemes decreases compared with that in path restoration scheme and link restoration scheme, although total wavelength mileage usage increases by 10% to 50%.

• The KIPS Transactions:PartC
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• v.9C no.4
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• pp.497-504
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• 2002

This paper proposes fault diagnosis and correction algorithms using agent collaboration, and a management model for managing network configuration faults. This management model is composed of three processes-fault detection, fault diagnosis and fault correction. Each process, based on RBR, operates on using rules which are consisted in Rule-based Knowledge Database. Proposed algorithm selves the complex fault problem that a system could not work out by itself, using agent collaboration. And the algorithm does efficiently diagnose and correct network configuration faults in abnormal network states.

• Journal of KIISE:Information Networking
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• v.30 no.3
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• pp.448-460
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• 2003

In this paper, we propose a network fault recovery algorithm based on a segment restoration scheme to reduce restoration time and restoration resource. The proposed segment restoration scheme is based on network partitioning which divides a large network into several small subnetworks. The restoration performance of the proposed segment restoration scheme depends on the size and the topology of subnetworks. Since most faults can be restored in a subnetwork, restoration time is reduced obviously. We compare and analyze restoration performance according to the size of subnetworks and restoration schemes. From simulation results, the proposed segment restoration scheme has the shortest restoration time compared with other restoration schemes. Especially the restoration performance of the proposed segment restoration scheme is better than the SLSP, which is also a segment-based restoration scheme, in terms of restoration time and required restoration resource capacity.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.10 no.1
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• pp.83-93
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• 2006

This paper introduces rule-based reasoning (RBR) based self-recovery system for network fault in ubiquitous computing. This system is fault management system for fault recovery of rule-based for self-recovery in ubiquitous computing environment. We proposed rules of network fault recovery applied the system as a distinguished reason of network fault. And, in this paper, the network fault self-recovery system proved the rules that applied each situatpion through the simulation.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.39 no.11
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• pp.1-11
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• 2002

To increase network survivability and to guarantee reliable services in MPLS networks, when failures occur either at any link or node of a working path, traffics on the failed path should be switched to other restoration paths. In this paper, we propose a path restoration method using duplication of working paths for link failure and its associated failure detection method, which utilizes OAM cells when all the duplicated links or nodes of the path failed. We analyze the performance of the proposed restoration method and show that especially the method is very efficient to restore high priority traffics. Also, through simulation we prove that the proposed restoration method is superior in performance to several existing methods suggested so far.