• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.11
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• pp.5200-5222
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• 2017

The separation of control plane and data plane in Software Defined Network (SDN) makes it flexible to control the network behavior, while also causes some inconveniences to the link failure recovery due to the delay between fail point and the controller. To avoid delay and packet loss, pre-defined backup paths are used to reroute the disrupted flows when failure occurs. However, it may introduce large overhead to build and maintain these backup paths and is hard to dynamically construct backup paths according to the network status so as to avoid congestion during rerouting process. In order to realize congestion aware fast link failure recovery, this paper proposes a novel method which installs multi backup paths for every link via source routing and per-hop-tags and spread flows into different paths at fail point to avoid congestion. We carry out experiments and simulations to evaluate the performance of the method and the results demonstrate that our method can achieve congestion aware fast link failure recovery in SDN with a very low overhead.

• 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.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37 no.5B
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• pp.357-364
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• 2012

In Visible Light Communication (VLC) system, with the limitation of transmission range and Field Of View (FOV), LOS (Line of Sight) link between two transceivers should be guaranteed due to the straightness of the visible-light signal. Especially for indoor applications, link recovery is an advantage method to remain the link connection because of the link failure in which caused by movement obstacle. Link recovery schemes try to keep link dynamically without re-initialing connection. This article proposes a new link recover scheme for VLC system by using cooperative communication. Our propose scheme focuses on the QoS reservation resource by GTS in IEEE 802.15.7 specification in which the requested QoS resource from client should be guarantee during the application time. With the link recovery scheme, we will try to continue the link connection as long as possible when unexpected disconnect link. The mathematical analysis and simulation results show that proposed scheme increases the overall reliability of the VLC system.

• Annual Conference of KIPS
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• 2013.11a
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• pp.400-401
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• 2013

Mobility in a network causes link disconnections and link recovery is vital for reliability of a network. A link failure affects all the preceding nodes on a damaged routing path; creates communication delay, throughput degradation, and congestion. This paper proposes link recovery mechanisms in CCN based networks. Packet overhearing is used to update neighboring nodes information. The recovery is done by forwarding node resulting in low control overhead, and better efficiency. The proposed mechanisms increase overall performance of a typical CCN and simulation results show that our proposed scheme works very well in densely populated networks with high mobility.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.2
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• pp.10-16
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• 2016

For higher reliability against a link failure of a control network in railway vehicles, a recovery mechanism is needed. We introduce a problem that, when a link failure occurs in a ring-topology control network, a node may experience a significant increase of transmission delay depending on its relative position within the network. We then propose two mechanisms to solve this problem: (1) differentiating and prioritizing node traffic in forwarding; and (2) switching some nodes to a backup bus-topology network. Our simulation study shows that, while the first mechanism achieves a limited gain by only compensating queuing delay, the second one gets a sufficient gain which is impacted by the number of nodes switched to the bus network.

• 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).

• 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 Korea Institute of Information, Electronics, and Communication Technology
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• v.8 no.6
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• pp.439-444
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• 2015

The Social infrastructure systems such as communication, transportation, power and water supply systems are now facing various types of threats including component failures, security attacks and natural disasters, etc. Whenever such undesirable events occur, it is crucial to recover the system as quickly as possible because the downtime of social infrastructure causes catastrophic consequences in the society. Especially when there is a network link-failure, we need an automatic link-recovery method. This means that customers are aware of network failures that can be recovered before you say that service. In this paper, we analysis the relation between Auto-recovery performance and cost.

• Journal of Information Technology Services
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• v.7 no.2
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• pp.181-195
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• 2008

The rapid growth of mobile communication technology has provided the expansion of mobile internet services, particularly mobile realtime transaction takes much weight among mobile fields. There is an increasing demand for various mobile applications to process transactions in a mobile computing fields. Thus, During transmission in wireless networks a base station failure inevitably causes data loss of the base station buffer. It is required to compensate the loss for communication. The existing methods for a base station failure are not adequate because they all suffer from too much overhead and resolve only the link failure. In this paper, we study an efficient recovry systems for a mobile DBMS. We propose SLL (Segment Log List) that enables the mobile host to compensate data loss efficiently in the case of base station failure. In SLL, a base station deliveries an output information of data cells to a mobile host. when a base station fails, the mobile host can retransmit just next data cells. We also prove the efficiency of new method.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.11 no.4
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• pp.331-339
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• 2018

The IEEE 1588, commonly known as a precision time protocol (PTP), is a standard for precise clock synchronization that maintains networked measurements and control systems. The best master clock (BMC) algorithm is currently used to establish the master-slave hierarchy for PTP. The BMC allows a slave clock to automatically take over the duties of the master when the slave is disconnected due to a link failure and loses its synchronization; the slave clock depends on a timer to compensate for the failure of the master. However, the BMC algorithm does not provide a fast recovery mechanism in the case of a master failure. In this paper, we propose a technique that combines the IEEE 1588 with network bonding to provide a faster recovery mechanism in the case of a master failure. This technique is implemented by utilizing a pre-existing library PTP daemon (Ptpd) in Linux system, with a specific profile of the IEEE 1588 and it's controlled through bonding modes. Network bonding is a process of combining or joining two or more network interfaces together into a single interface. Network bonding offers performance improvements and redundancy. If one link fails, the other link will work immediately. It can be used in situations where fault tolerance, redundancy, or load balancing networks are needed. The results show combining IEEE 1588 with network bonding enables an incredible shorter recovery time than simply just relying on the IEEE 1588 recovery method alone.