• Journal of KIISE:Computer Systems and Theory
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• v.29 no.3
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• pp.117-124
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• 2002

This paper proposes a fault-tolerant multicasting algorithm employing the region encoding scheme in multistage interconnection networks (MIN's) containing multiple faulty switching elements. After classifying all switching elements into two subsets with equal sizes in MIN, the proposed algorithm can tolerate the faulty pattern where every fault is contained in the same subset. In order to send a multicast message to its destinations detouring faults, the proposed algorithm uses the recursive scheme that recirculates it through MIN, We prove that this algorithm can route any multicast message in only two passes through the faulty MIN.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.38B no.11
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• pp.911-923
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• 2013

Multipath routing is one of challenging issues for improving the reliability of end-to-end data delivery in wireless sensor networks. Recently, a disjointedness and management of path have been studying to enhance the robustness and efficiency of the multipath routing. However, previous multipath routing protocols exploit the disjointed multipath construction method that is not to consider the wireless communication environment. In addition, if a path failures is occurred due to the node or link failures in the irregular network environment, they maintain the multipath through the simple method that to construct a new extra path. Even some of them have no a method. In order to cope with the insufficiency of path management, a hole detouring scheme, to bypass the failures area and construct the new paths, was proposed. However, it also has the problem that requires a heavy cost and a delivery suspension to the some or all paths in the hole detouring process due to the centralized and inflexible path management. Due to these limitations and problems, the previous protocols may lead to the degradation of data delivery reliability and the long delay of emergency data delivery. Thus, we propose a flexible disjoint multipath routing protocol which constructs the radio disjoint multipath by considering irregular and constrained wireless sensor networks. It also exploits a localized management based on the path priority in order to efficiently maintain the flexible disjoint multipath. We perform the simulation to evaluate the performance of the proposed method.

• Journal of KIISE:Computer Systems and Theory
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• v.30 no.5_6
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• pp.273-279
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• 2003

Hypercube multicomputers have been drawing considerable attention from many researchers due to their regular structure and short diameter. One of keys to the performance of Hypercube is the efficiency of communication among processors. Among several communication patterns, multicast is important, which is found in a variety of applications as data replication and signal processing. As the number of processors increases, the probability of occurrences of fault components also increases. So it would be desirable to design an efficient scheme that multicasts messages in the presence of faulty component. In fault-tolerant routing and multicast, there are local information based scheme, global information based scheme and limited information based scheme in terms of information. In general, limited information is easy to obtain and maintain by compressing information in a concise format. In this paper, we propose a new routing scheme and a new multicast scheme using recently proposed fully reachability information scheme and new local information scheme. The proposed multicast scheme increases multicast success possibility and reduce deroute cases. Experiments show that multicast success possibility can increase at least 15% compared to previous method.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.8A
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• pp.1169-1176
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• 2000

In this paper, label assignment schemes considering the IP flow model for the efficient MPLS traffic engineering are proposed and evaluated. Based on the IP flow model, the IP flows are classified into transient flows and base flows. Base flows, which last for a long time, transmit data in high bit rate, and be composed of many packets, have good implications for the MPLS traffic engineering, because they usually cause network congestion. To make use of base flows for the MPLS traffic engineering, we propose two base flow classifiers and label assignment schemes where transient flows are allocated to the default LSPs and base flows to explicit LSPs. Proposed schemes are based on the traffic-driven label triggering method combined with a routing tabel. The first base flow classifier uses both flow size in packet counts and routing entries, and the other one, extending the dynamic X/Y flow classifier, is based on a cut-through ratio. Proposed schemes are shown to minimize the number of labels, not degrading the total cut-through ratio.

• Journal of Digital Contents Society
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• v.19 no.8
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• pp.1545-1554
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• 2018

In order to support the mobility of the wireless devices, at least two APs (Access Points) must be arranged in a single AP area to maintain communication area. In the WLAN (Wireless LAN) environment, seamless handover is one of the most important issues in terms of effective utilization of wireless networks and maximization of services for users. On the other hand, SDN (Software-Defined Networking), which is emerging rapidly in recent years, is revolutionizing network management in terms of flexibility, fine control, and convenience. SDN originally reduces latency time or increases network robustness by real-time flow table control reducing or bypassing paths between switches in LAN-based data centers. In this study, we apply OpenFlow, a SDN platform focused on wired LAN, to a dense WLAN environment using legacy APs to implement and evaluate seamless handover for streaming services of digital contents.

• The Journal of Society for e-Business Studies
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• v.16 no.4
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• pp.75-85
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• 2011

Although progress in information technology has made our life prosperous. But it accompanied a number of adverse effects in various aspects. Especially, internet according to the increasing requirements for privacy and security, IP concealment network technologies to ensure the anonymity are constantly being developed. IP concealment network technologies is aiding the user to bypass the blocked sites can be used to access for information gathering, and they could be used for a malicious hacker to hide his attacks. However, due to complex routing path, local communication bandwidth sangyiham, and internode encryption there are also disadvantages that communication speed is significantly less. In this paper, the research for improving the performance of anonymous networks is to proceed by the communication speed measurement that using GeoIP the particular country with high-bandwidth is Specified or path length is limited.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.28 no.10A
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• pp.796-806
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• 2003

Mobile Node usually communicate with CN bia only it's own HA but Nested Mobile Networks correspond with CN bia all HA involved with them. when Mobile Network of a MR moves from its home link to a foreign link in the stationary network. then Mobile Network of another MR moves from its home link in stationary network to foreign link in previous mobile network. CN send Packet destined to the latter MR via both Home Agent of the former MR and the latter MR. There are two problem in this scenario. One is inefficient routing path that bypass via several HA. the other is waste of transmission resource and delay of Registration process which change of Nested Mobile Network Architecture cause Mobile Router. so We propose MRA(Mobile Relay Agent) to support effective routing by local mobility management.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.21 no.3
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• pp.91-98
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• 2021

In most hacking attacks, hackers tend to access target systems in a variety of circumvent connection methods to hide their original IP. Therefore, finding the attacker's IP(Internet Protocol) from the defender's point of view is one of important issue to recognize hackers. If an attacker uses a proxy, original IP can be obtained through a program other than web browser in attacker's computer. Unfortunately, this method has no effect on the connection through VPN(Virtual Private Network), because VPN affects all applications. In an academic domain, various IP traceback methods using network equipments such as routers have been studied, but it is very difficult to be realized due to various problems including standardization and privacy. To overcome this limitation, this paper proposes a practical way to use client's network configuration temporarily until it can detect original IP. The proposed method does not only restrict usage of network, but also does not violate any privacy. We implemented and verified the proposed method in real internet with various VPN tools.

• Journal of the Korea Society of Computer and Information
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• v.14 no.4
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• pp.69-76
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• 2009

The construction of Internet IP-based Network is composed of router and switch models in a variety of companies. The construction by various models causes the complexity of the management and control as different types of CLI is used by different company to filter out abnormal traffics like worm, virus, and DDoS. To improve this situation, IETF is working on enacting XML based configuration standards from NETCONF working group, but currently few commands processing at the level of operation layer on NETCONF are only standardized and it's hard for unified control operation process between different make of system as different company has different XML command to filter out abnormal traffics. This thesis proposes ways to prevent abnormal attacks and increase efficiency of network by re-routing the abnormal traffics coming thru unified control for different make of systems into Sinkhole router and designing a control system to efficiently prevent various attacks after checking the possibility of including abnormal traffics from unified control operation.

• The KIPS Transactions:PartC
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• v.12C no.1 s.97
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• pp.83-96
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• 2005

The multichannel switch is an architecture widely used for ATM (Asynchronous Transfer Mode). It is known that the fault tolerant characteristic can be incorporated into the multichannel crossbar switching fabric. For example, if a link belonging to a multichannel group fails, the remaining links can assume responsibility for some of the traffic on the failed link. On the other hand, if a fault occurs in a switching element, it can lead to erroneous routing and sequencing in the multichannel switch. We investigate several fault localization algorithm in multichannel crossbar ATM switches with a view to early fault recovery. The optimal algorithm gives the best performance in terms of time to localization but it is computationally complex which makes it difficult to implement. We develop an on-line algorithm which is computationally more efficient than the optimal one. We evaluate its performance through simulation. The simulation results show that the Performance of the on-line algorithm is only slightly sub-optimal for both random and bursty traffic. There are cases where the proposed on-line algorithm cannot pinpoint down to a single fault. We enumerate those cases and investigate the causes. Finally, a fault recovery algorithm is described which utilizes the information provided by the fault localization algorithm The fault recovery algorithm providesadditionalrowsandcolumnstoallowcellstodetourthefaultyelement.