• The KIPS Transactions:PartC
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• v.9C no.4
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• pp.505-512
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• 2002

Rerouting mechanisms must be used by connections in order to provide QoS (Quality of service) characterization of services, which provides mean for reliable and efficient transfer of services under fault generating network. Also, user's services can classily according to their QoS characterizations. In this paper, we study classification of user services according to their characterization for providing differentiated services, and propose rerouting mechanisms under fault generating network. For this, we study various rerouting mechanisms including rerouting locus of start (Source Rerouting, Link Rerouting), rerouting timing of start (Immediate Rerouting, Random Rerouting) and their orthogonal relationship, eventually we propose new rerouting mechanisms such as DRIT, DRDT which show higher performance according to priority of services than others. Our simulation shows that rerouting mechanism (DRDT), applied differentiated mechanisms is better performance to provide differentiated service.

• The KIPS Transactions:PartC
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• v.9C no.5
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• pp.655-664
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• 2002

The focus of quality-of-service routing has been on the routing of a single path satisfying specified QoS constraints. However upon failure of a node or link on the path, a new path (backup path) satisfying the constraints has to be established. This paper proposed the fault recovery QoS Rerouting algorithms to recovery the service of applications under fault environment of network. For this, we describes the generation method of PFC (Protection Fundamental Cycle) protecting all of network nodes and suggests path selection algorithms using minimization rerouting cost problem and analyzes the performances of these.

• Journal of Communications and Networks
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• v.9 no.4
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• pp.356-367
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• 2007

In large networks, maintaining precise global network state information is impossible. The imprecise network state information has significant impacts on Quality-of-Service(QoS) routing and path establishment. In this paper, we develop analytical models for investigating the QoS routing schemes that are designed to tolerate imprecise network state information, and study the performance of various QoS routing schemes, including randomized routing, multi-path routing, and probability based routing, using both the models and simulations. We further propose a new mechanism, called local rerouting, that improves the effectiveness of QoS path establishment in the presence of imprecise global network state information. Local rerouting is orthogonal to existing schemes for dealing with imprecise state information and can be used in conjunction with them to alleviate the impacts of the imprecise information. The results of our performance study indicate that local rerouting is robust and effective.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.9B
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• pp.791-798
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• 2004

In case of failure in the IP network, services should be provided via a backup path which fully meets QoS requirements. In this regard, we in this paper suggest simple-PFC(s-PFC) to restore single link failure, iterative-PFC(i-PFC) for multiple link failures, and fault_node Avoidance-PFC(a-PFC) for failures of nodes such as routers. Taking the minimum cost rerouting problem into account, we compare and analyze performance of those three mechanisms carrying out Direct-destination Rerouting(DR).

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.10B
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• pp.841-848
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• 2004

In case of failure in the IP network services should be provided via a backup path which fully meets QoS requirements. In this regard, we in this paper suggest simple-PFC(5-PFC) to restore single link failure, iterative-PFC(i-PFC) for multiple link failures, and fault_node Avoidance-PFC(a-PFC) for failures of nodes such as routers. Taking the minimum cost rerouting problem into account, we compare and analyze performance of those three mechanisms carrying out Direct_destination Rerouting(DR).

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.9
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• pp.4287-4306
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• 2016

Network resilience provides an effective way to overcome the problem of network failure and is crucial to Internet protocol (IP) network management. As one of the main challenges in network resilience, recovering from link failure is important to maintain the constancy of packets being transmitted. However, existing failure recovery approaches do not handle the traffic engineering problem (e.g., tuning the routing-protocol parameters to optimize the rerouting traffic flow), which may cause serious congestions. Moreover, as the lack of QoS (quality of service) restrictions may lead to invalid rerouting traffic, the QoS requirements (e.g., bandwidth and delay) should also be taken into account when recovering the failed links. In this paper, we first develop a probabilistically correlated failure model that can accurately reflect the correlation between link failures, with which we can choose reliable backup paths (BPs). Then we construct a mathematical model for the failure recovery problem, which takes maximum rerouting traffic as the optimizing objective and the QoS requirements as the constraints. Moreover, we propose a heuristic algorithm for link failure recovery, which adopts the improved k shortest path algorithm to splice the single BP and supplies more protection resources for the links with higher priority. We also prove the correctness of the proposed algorithm. Moreover, the time and space complexity are also analyzed. Simulation results under NS2 show that the proposed algorithm improves the link failure recovery rate and increases the QoS satisfaction rate significantly.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.35S no.1
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• pp.39-51
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• 1998

In this paper, we propose signaling procedures amon network elements for a connection rerouting method which can reduce inter-switch handoff processing delay reduces the delay in the connection re-routing by reserving VPI/VCIs for possible inter-switch handoff calls in advance. Additionally, we mathematically analyze the signaling procedures and then suggest solutions to the relations with cluser size, network topoloty, handoff-request rete and handoff delay. With simulation, the solutions are validated. From numerical examples, we concluded taht handoff delay, one of the handoff QoSs, can be satisfied by adjusting the cluster size and network topology according to the handoff -request rate of service area. With our proposed signaling and analytic methods, we concluded that the connection rerouting method using cluster-sectoring effectively reduces the delay of inter-switch handoff processing than dynamic connection rerouting method. Our solutions are useful in guaranteeing the requested handoff delay (especially, inter-switch handoff delay) when the connection rerouting method is applied to ATM-based wireless/wired integrated network.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.5 no.3
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• pp.465-474
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• 2001

In the network with small cell radius, a mobile terminal which has large mobility should perform frequent handover. This requires that handover mechanism must be done fastly. The currently existing method for handover uses an algorithm in which the bandwidth corresponding to the adjacent cells is supposed to be allocated. However, this method leads to the problem of requiring bandwidth allocation for many-unknown cells, due to the lack of information toward moving direction in mobile terminal. In this paper, we propose an efficient dynamic bandwidth allocation algorithm for solving those problem above, based on both path rerouting handover and soft handover mechanism with wireless ATM. As for the QoS, it has been shown that proposed algorithm shows better performance than that with static bandwidth allocation algorithm.

• Proceedings of the IEEK Conference
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• 1999.06a
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• pp.110-113
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• 1999

In this paper. we propose an adaptive handover scheme in wireless network The proposed handover scheme is a hybrid type of virtual path extension and rerouting. The proposed handover scheme chooses the virtual path management scheme according to the service QoS instead of the network topology which is used in the previous hybrid handover schemes. The proposed scheme supports the seamless service and small buffering during virtual path rerouting handover through the multicasting service. To evaluate the performance of the proposed scheme. we compute the number of signaling message used for handover and perform computer simulation. The simulation results show that the proposed scheme provides more efficiency in the handover delay and seamless service than the previous methods.

• Journal of Communications and Networks
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• v.11 no.3
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• pp.297-305
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• 2009

Multiprotocol label switching (MPLS) networks require dynamic flow admission control to guarantee end-to-end quality of service (QoS) for each Internet protocol (IP) traffic flow. In this paper, we propose to tackle the joint routing and admission control problem for the IP traffic flows in MPLS networks without rerouting already admitted flows. We propose two mathematical programming models for this problem. The first model includes end-to-end delay constraints and the second one, end-to-end packet loss constraints. These end-to-end QoS constraints are imposed not only for the new traffic flow, but also for all already admitted flows in the network. The objective function of both models is to minimize the end-to-end delay for the new flow. Numerical results show that considering end-to-end delay (or packet loss) constraints for all flows has a small impact on the flow blocking rate. Moreover, we reduces significantly the mean end-to-end delay (or the mean packet loss rate) and the proposed approach is able to make its decision within 250 msec.