• Journal of Internet Computing and Services
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• v.4 no.2
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• pp.1-9
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• 2003

Path restoration, which is needed to increase network survivability in MPLS networks, is a technology of supplying reliable service by delivering the traffics through restoring the paths when links or nodes of a working path are failed. In this paper, we propose a path restoration method using duplication of working paths for link failure as a method of restoring paths for the high priority traffics. The existing path restoration method transmits the traffics to the path restoration uniformly in regardless of the priority while link obstacle. It has a problem to take a long time to restore the connection of the high priority traffics. On the other hand, the suggested restoration method establishes the duplication path for the working path, which transmits the high priority traffics and transmit the traffics through the duplication path. It has a strong point to restore the connection quickly. Also, through simulation we analyze the performance of the restoration system using the duplication path and prove that the proposed restoration method is superior in performance to the existing restoration methods regarding to the high priority traffics.

• The KIPS Transactions:PartC
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• v.10C no.2
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• pp.155-162
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• 2003

Fast restoration time and service guarantee are the important goals to achieve the network reliability. In the protection switching scheme, one way to guarantee service fro an application session if a network happens to fail is to establish the restoration path that amounts to the same bandwidth of the working path of the session at the same time. When we setup the restoration path, we can reduce the bandwidth consumption by the restoration path if the path can share the bandwidth required by the other paths. This paper explains the methods how to determine the shared bandwidth of the restoration path in the protection switching scheme, given the maximum bandwidth assigned to a link along the working path. We point out that such sharing algorithm can not reduce the bandwidth consumption by the restoration paths in some cases, which contradict the general conception. We explain why this can happen, and show the simulation results in real network topologies to prove our arguments. We explain the reason of the failure of the sharing effect by the simple sharing algorithm. Finally we propose the way of how we can overcome the failure of the sharing effect, using the complete sharing algorithm based on the link database and showing the results.

• 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.12C no.3 s.99
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• pp.401-408
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• 2005

We propose a new MPLS restoration scheme that uses network resources more efficiently and minimizes the backup path cost effectively. Contrary to other restoration strategies, the proposed restoration scheme starts the recovery action at the selected node of a working LSP. At LSP setup, the working and backup path cost is evaluated and the starting node of restoration is designated. By doing so, the restoration speed could be further increased and resource utilization could be maximized. We simulated the proposed scheme and compared with other restoration and protection schemes. The result shows that our scheme can provide fast restoration with acceptable delay and loss characteristics.

• 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.

• Journal of information and communication convergence engineering
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• v.6 no.1
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• pp.15-18
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• 2008

WDM is an incredibly promising technique in which multiple channels are operated along a single fiber, providing the facilities of terabit per second bandwidth. Thus, the survivability of WDM networks becomes critical for the success of the next generation internet architecture. Despite the fact that the path-based proactive restoration scheme guarantees 100% restoration as it computes a backup light path while the primary light path is being set up, this method results in additional capacity consumption. In this paper, an ideal technique is proposed that modifies the active multi-backup paths method and results in a better restoration scheme. Based on a theoretical analysis, a new method is shown to reduce the number of hopes as well as the restoration time.

• The Journal of Advanced Prosthodontics
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• v.2 no.2
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• pp.46-49
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• 2010

BACKGROUND. Though implant dentistry is very successful and predictable in treatment of patients with destroyed dentition, there are some cases with limitations to implant therapy. In these cases, alternative treatment modality should be considered. CASE DESCRIPTION. A patient with destroyed dentition was rehabilitated with a lateral rotational path removable partial denture. According to the diagnosis, we determined to raise vertical dimension for esthetic and functional restoration. The final restoration was performed after four months of provisional period. CLINICAL IMPLICATION. The edentulous patients with compromised esthetics and functions can be successfully treated with a rotational path removable partial denture through adequate treatment planning and precise laboratory procedure.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.27 no.11C
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• pp.1046-1054
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• 2002

In this paper, we propose a subnetwork-based segment restoration scheme to reduce the restoration time and restoration resources. And we compare and analyze the restoration performance according to the size of divided subnetworks. Segment restoration is based on network partitioning where a large network is divided into several small subnetworks and the end-to-end data path is divided into multiple segments according to the subnetworks. In segment restoration, the link/node failure is restored by segment instead of end-to-end path. Because most faults are restored within the subnetwork, the restoration performance can be improved. From the simulation analysis, we verified that the proposed segment restoration has advantage of restoration time and backup resource utilization.

• Journal of KIISE:Information Networking
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• v.27 no.2
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• pp.187-196
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• 2000

Failures in ATM networks can occur at virtual path (VP) links, virtual path switches, and virtual channel (VC) switches. Restoration schemes have been proposed for VP link and VP switch failures, however, none for VC switch failures. In general, VC switches are used for edge nodes in protection domains. Since even only one VC switch failure can cause a critical problem, new restoration schemes for VC switch failures are highly required. Restoration schemes at the VP level proposed so far can be categorized into those using the flooding algorithm and those using the backup virtual path (BVP) concept. Even though the latter cannot handle unpredictable failures, it has some advantages such as fast restoration and low spare capacity requirement. In this paper, we propose new restoration schemes using a new type of BVPs to handle VC switch failures. The simulation results show that the proposed schemes can restore virtual connection failures due to VC switch failures without degrading restorability for VP failures.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.5B
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• pp.850-858
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• 2000

Increased network reliability is required as the size of communication network becomes larger and the bandwidth requirement is increasing. And preparing of backup path is required to protect the network from serious network failures in high speed network. In this paper, we construct multiple logical networks on a physical ATM network according to the ATM bearer service category(CBR, rt-VBR, nrt-VBR, ABR, UBR) defined by ATM Forum to support the required QoS(Quality of Service) and to manage the network more efficiently. We use backup path restoration algorithm rather than dynamic restoration to achieve rapid restoration when active path fails and we use fault management function in TINA. We propose a restoration scheme that is suitable for high-speed network.