• KSII Transactions on Internet and Information Systems (TIIS)
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• v.7 no.5
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• pp.1198-1212
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• 2013

Network virtualization enables autonomous and heterogeneous Virtual Networks (VNs) to co-exist on a shared physical substrate. In a Network Virtualization Environment (NVE), the fact that individual VNs are underpinned by diverse naming mechanisms brings about an obvious challenge for transparent communication across multiple VN domains due to the complexity of uniquely identifying users. Existing solutions were mainly proposed compatible to Internet paradigm with little consideration of their applications in a virtualized environment. This calls for a scalable and efficient naming framework to enable consistent communication across a large user population (fixed or mobile) hosted by multiple VNs. This paper highlights the underlying technical requirements and presents a scalable Global Naming Framework (GNF), which (1) enables transparent communication across multiple VNs owned by the same or different SPs; (2) supports communication in the presence of dynamics induced from both VN and end users; and (3) greatly reduces the network operational complexity (space and time). The suggested approach is assessed through extensive simulation experiments for a range of network scenarios. The numerical result clearly verifies its effectiveness and scalability which enables its application in a large-scale NVE without significant deployment and management hurdles.

• The KIPS Transactions:PartC
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• v.8C no.5
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• pp.543-550
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• 2001

In this paper, an improved detection system for the network vulnerability scan attacks is proposed. The proposed system improves the methodology for detecting the network vulnerability scan attacks and provides a global detection and response capability that can counter attacks occurring across an entire network enterprize. Through the simulation, we show that the proposed system can detect vulnerable port attacks, coordinated attacks, slow scans and slow coordinated attacks. We also show our system can achieve more global and hierarchical response to attacks through the correlation between server and agents than a stand-alone system can make.

• IE interfaces
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• v.23 no.2
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• pp.108-117
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• 2010

Wireless sensor network may be installed where it is hard to access or where one has to constantly gather data without any human's monitoring. Sensors which compose a sensor network are usually small with poor battery capacities and thus energy-efficient usage is very important because of difficulties in replacing or recharging the batteries to make the lifetime of the whole sensor network longer. LEACH protocol, a well-known hierarchical routing protocol, may resolve this problem by distributing the role of cluster header evenly to the sensor nodes in the whole area of network at each round. In this thesis, we introduce a variant of LEACH protocol which considers the distance between base station and sensors in the way that if a node is far from the base station then the probability that this node becomes a cluster header is low. Experiments to evaluate the energy efficiency and the ability to collect the information show that the proposed method in this paper has maintained much wider sensing area while keeping the energy efficiency same as LEACH.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.35 no.5B
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• pp.741-752
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• 2010

The ability to seamlessly switch between the macro networks and femtocell networks is a key driver for femtocell network deployment. The handover procedures for the integrated femtocell/macrocell networks differ from the existing handovers. Some modifications of existing network and protocol architecture for the integration of femtocell networks with the existing macrocell networks are also essential. These modifications change the signal flow for handover procedures due to different 2-tier cell (macrocell and femtocell) environment. The handover between two networks should be performed with minimum signaling. A frequent and unnecessary handover is another problem for hierarchical femtocell/macrocell network environment that must be minimized. This work studies the details mobility management schemes for small and medium scale femtocell network deployment. To do that, firstly we present two different network architectures for small scale and medium scale WCDMA femtocell deployment. The details handover call flow for these two network architectures and CAC scheme to minimize the unnecessary handovers are proposed for the integrated femtocell/macrocell networks. The numerical analysis for the proposed M/M/N/N queuing scheme and the simulation results of the proposed CAC scheme demonstrate the handover call control performances for femtocell environment.

• Convergence Security Journal
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• v.12 no.4
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• pp.49-55
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• 2012

In this paper, we consider the limit of the previous works for ad-hoc network, then propose a dynamic routing scheme which employs a 2-tier hierarchical structure. We adopt the advantages of proactive and reactive routing scheme for efficient network management. We define this method as NSDR(New Secure Dynamic Routing) scheme. We also propose a trustworthy authentication and key management for the proposed ad-hoc network. We currently study the possibility that ad-hoc networks can provide a service such as key management and authentication for the next generation mobile network.

• The Transactions of the Korea Information Processing Society
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• v.3 no.5
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• pp.1198-1206
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• 1996

This paper proposes the functionality of communication network management which operates in central control station of satellite communication network, which will be constructed to DAMA-SCPC ground station using KORE ASAT. And communication network configuration components are classified with hierarchical structure in order to efficiently maintain communication network operation management, and configuration components that are classified into graphic objects and this graphic objects are visualized with tree structure which can be handled uniformally and efficiently. In addition to that, this paper proposes expression method of graphic object to implement our real time communication network management system, and the real time communication net-work management composed as client-server system. The performance of the proposed algorithm is analyzed through the computer simulation.

• The KIPS Transactions:PartC
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• v.9C no.3
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• pp.431-438
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• 2002

SNMP is a simple, application layer protocol and that is sending and receiving the management information among network devices. It exchanges the management information by the PDUs that have the management information names and values. Until now, network management is so inconvenience because of console-based management by using SNMP. This paper shows the Web-based SNMP network management system that is using the designed private MIB and GUI. In this paper, we have proposed a virtual SNMP agent supporting scalability of network management. With the virtual agent, large-scale network can be managed simply by trap filtering and hierarchical management.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.2B
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• pp.82-89
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• 2008

Mobile IP is the basic solution to provide host mobility, whereas network mobility refers to the concept of collective mobility of a set of nodes. In a network mobility scenario, mobile networks can be nested in a hierarchical form. That situation is referred to a nested mobile network Nested mobile networks exhibit the pinball routing problem, which becomes worse in proportion to the number of nested levels in the hierarchy. In this paper, we propose a routing optimization scheme having backward compatibility to the basic network mobility protocol and concerning heterogeneity of nested mobile network, also we perform comparison and analysis of proposed schemes.

• Journal of KIISE:Computer Systems and Theory
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• v.30 no.11
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• pp.675-690
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• 2003

In this paper, we present the virtual dancing studio for distributed virtual environment. In this system, geographically distributed user shares the virtual dancing hall and interacts with each other. The participating object can be a graphical avatar or a live video stream. It allows the coexistence of graphic objects and real images in the shared virtual space. One of the main technical challenges in developing the distributed virtual environment is to handle excessive network traffic. In an effort to effectively reduce the network traffic, we propose a scheme to adjust the QoS of each object with respect to the distance from the observer in the virtual space. The server maintains the QoS vector for each client's shared space and controls the packet traffic to individual clients based on its QoS vectors. We develop a proto-type virtual dancing environment. Java based development enables the client to be platform independent. The result of experiment shows that the adoption of hierarchical QoS management significantly reduces the overall network traffic.

• Journal of Internet Computing and Services
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• v.5 no.5
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• pp.27-37
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• 2004

The existing ad hoc network protocols suffer the scalability problem due to the inherent characteristics of node mobility. Cluster-based routing protocols divide the member nodes into a set of clusters and perform a hierarchical routing between these clusters. This hierarchical feature help to improve the scalability of ad hoc network routing. However, previous k-hop cluster-based routing protocols face another problems, that is, control overhead of the cluster headers. This paper proposes a novel k-hop cluster-based routing scheme with delegation functions for mobile ad hoc networks. The scheme employs is based on tree topology to manage cluster members in effectively. The cluster headers do not manage the routing table for whole members, while the header keeps the routing table for its neighbor members and the member list for one hop over nodes within k-hop cluster. Then the in-between leveled nodes manage the nested nodes which is structured in the lower level. Therefore, the proposed mechanism can reduce some control overhead of the cluster leaders.