• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.1
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• pp.175-178
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• 2005

인터넷 상의 불특정 다수의 컴퓨팅 자원을 연계하여 오버레이 네트워크를 구성하여 새로운 컴퓨팅 인프라를 구성하려는 분산 해쉬 테이블 (Distributed Hash Table)방식의 Peer-to-Peer(P2P) 네트워크 관련 연구가 진행되고 있다. DHT 방식의 P2P네트워크는 자원의 복제 및 공유하여 컴퓨팅 시스템 전반에 걸친 신뢰성과 결함 감내 능력을 향상시키는 장점이 있는 반면에 하부 네트워크 정보를 무시하기 때문에 전체 시스템 구성 및 메시지 전송에 있어 실제적인 성능상의 문제점을 드러낸다. 이 논문에서는 하부 네트워크의 구성 정보를 이용하여 DHT 기반의 P2P 네트워크의 메시지 전송 방식의 효율을 높이는 방법을 소개한다.

• The KIPS Transactions:PartC
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• v.16C no.6
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• pp.761-772
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• 2009

A DHT(Distributed Hash Table) based P2P is a method to overcome disadvantages of the existing unstructured P2P method. If a DHT algorithm is used, it can do a fast data search and maintain search efficiency independent of the number of peer. The peers in the DHT method send messages periodically to keep the routing table updated. In a mobile environment, the peers in the DHT method should send messages more frequently to keep the routing table updated and reduce the failure of a request. Therefore, this results in increase of network traffic. In our previous research, we proposed a method to reduce the update load of the routing table in the existing Chord by updating it in a reactive way, but the reactive method had a disadvantage to generate more traffic than the existing Chord if the number of requests per second becomes large. In this paper, we propose an adaptive method of routing table update to reduce the network traffic. In the proposed method, we apply different routing table update method according to the number of request message per second. If the number of request message per second is smaller than some threshold, we apply the reactive method. Otherwsie, we apply the existing Chord method. We perform experiments using Chord simulator (I3) made by UC Berkeley. The experimental results show the performance improvement of the proposed method compared to the existing methods.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.12B
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• pp.818-830
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• 2005

Recently, Peer-to-Peer (P2P) overlay networks like CAN, Chord, Pastry and Tapestry offer a novel platform for scalable and decentralized distributed applications. These systems provide efficient and fault-tolerant routing, object location, and load balancing within a self-organizing overlay network. Content Delivery Network (CDN) is an intermediate layer of infrastructure that helps to efficiently deliver the multimedia content from content providers to clients. In this paper, We propose a topology-aware P2P overlay network for CDN, Rosary, in which CDN servers perform Intra-Pastry and Inter-Pastry routing based on a two-level structured overlay network. This proposed system extends pastry by adapting itself to CDN environments, where a semi-hashing based scheme for Intra-Pastry routing is introduced, and dynamic landmark technology is used to construct the topology-aware overlay network. Through simulations on NS-2, it is shown that Rosary is scalable, efficient, and flexible.

• Journal of Computing Science and Engineering
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• v.5 no.1
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• pp.19-31
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• 2011

In this paper, we propose two new routing schemes for double-layered peer-to-peer systems; a shorter-lower mobility routing scheme and a reverse path routing scheme. The shorter-lower mobility routing scheme first chooses shortest routing paths among possible routing paths and selects the path associated with the relay peer who has lower mobility to improve the reliability of the system. The reverse path routing scheme carries out unicasting (instead of multicasting) based on the reverse path information that can be obtained during the initial file search to further reduce network traffic. The experimental results showed that a double-layered peer-topeer system with the proposed hybrid scheme improved the reliability of the system about 1.5% over the hop count scheme and reduced network traffic by about 0.5% compared to the hop count scheme.

• The KIPS Transactions:PartC
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• v.16C no.6
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• pp.773-782
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• 2009

A DHT(Distributed Hash Table) based P2P is a method to overcome disadvantages of the existing unstructured P2P method. If a DHT algorithm is used, it can do a fast data search and maintain search efficiency independent of the number of peer. The peers in the DHT method send messages periodically to keep the routing table updated. In a mobile environment, the peers in the DHT method should send messages more frequently to keep the routing table updated and reduce the failure of a request. Therefore, this results in increase of network traffic. In our previous research, we proposed a method to reduce the update load of the routing table in the existing Chord by updating it in a reactive way, but the reactive method had a disadvantage to generate more traffic than the existing Chord if the number of requests per second becomes large. In this paper, we propose an adaptive method of routing table update to reduce the network traffic. In the proposed method, we apply different routing table update method according to the number of request message per second. If the number of request message per second is smaller than some threshold, we apply the reactive method. Otherwsie, we apply the existing Chord method. We perform experiments using Chord simulator (I3) made by UC Berkeley. The experimental results show the performance improvement of the proposed method compared to the existing methods.

• Journal of the Korea Computer Industry Society
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• v.4 no.12
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• pp.873-886
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• 2003

Lookup Is one of important factors for network traffic on peer-to-peer network. Especially, large amount of network resources are required for lookup process in p2p file sharing system that clients use the dynamic If and they import to p2p network in random. In this paper, we employ efficient lookup mechanism which searches lookup with the combined information of ISP key values and the extracted key values from SHA-1 hashing function for shared contents id. The proposed mechanism efficiently searches files on the network because the mechanism processes P2P lookup with consideration the routing information of ISP. We suggest the adapted simulation environment based upon the famous file sharing system of emule P2P and experiment the proposed system.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.11B
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• pp.938-945
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• 2004

This paper describes the problems of the existing two multi-layer routing policies(policy 1 and policy 2) and suggests new multi-layer routing policy(policy 3) which is established the packet LSP by inquiry on packet LSP lambda routing tables for GMPLS based optical If Network. All policies of multi-layer routing schemes first try to allocate a newly requested electrical path to an existing optical path that directly connects the source and destination nodes. U such a path is not available, all policies employ different procedures. Policy 1 tries to find available existing optical paths with two or more hops that connect the source and destination nodes and policy 2 tries to establish a new one-hop optical path between source and destination nodes. Policy 3 tries to establish a new one-hop optical path by inquiry on information of the packet LSP lambda routing tables between source and destination nodes. The performances of the three multi-routing policies are evaluated by computer simulation. Simulation results show that policy 3 is the excellent of routing time and traffic acceptance capabilities compare to existing two polices if p is large, where p is the number of packet-switching-capable ports p.

• Proceedings of the Korean Information Science Society Conference
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• 2004.04a
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• pp.688-690
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• 2004

지금까지의 P2P 알고리즘들은 링크가 비교적 안정적이고 움직임이 적은 유선망을 기반으로 만들어졌다. 하지만 무선의 경우 우선 전파의 손실률이 높아 링크의 안정성이 떨어지고 노드들의 이동성 때문에 링크의 연결 관계가 수시로 변하게 된다. 이러한 이유로 기존의 P2P알고리즘들을 무선에 직접적용하기 힘들다. 따라서 본 논문에서는 기존의 P2P방식이 우선 에드혹 네트워크에서 나타낼 수 있는 문제점을 지적하고 이를 해결하기 위한 P2P방식을 제안하였고 실험을 통하여 검증하였다.

• The KIPS Transactions:PartC
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• v.16C no.1
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• pp.73-82
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• 2009

The peers in the Chord method send messages periodically to keep the routing table updated. In a mobile P2P network, the peers in the Chord method should send messages more frequently to keep the routing table updated and reduce the failure of a request. However this results in increasing the overall network traffic. In our previous method, we proposed a method to reduce the update load of the routing table in the existing Chord by updating it in a reactive way, but there were disadvantages to generate more traffic if the number of requests per second increases and to have more delay in the request processing time than the existing Chord. In this paper, we propose an improved method of reactive routing table update to reduce the request processing time. In the proposed method, when a data request comes, the routing table is updated only if its information is not recent while it is always updated in the previous method. We perform experiments using Chord simulator (I3) made by UC Berkely. The experimental results show the performance improvement of the proposed method compared to the existing method.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.7B
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• pp.728-733
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• 2009

An ubiquitous environment has features like peer-to-peer and nomadic environments. Such features can be represented by peer-to-peer systems and mobile ad-hoc networks. P2P systems and MANETs share similar features, appealing for implementing P2P systems in MANET environment. However, if a P2P system designed for wired networks was applied to mobile ad-hoc environment, its performance was not good enough. Subsequently, this paper proposes a P2P system to improve performance using cross-layer design and the goodness of a node as a peer by using routing metric and P2P metric to choose favorable peers to connect. It also utilizes proactive approach for distributing peer information. The simulation results showed that the proposed system produced better performance in query success rate, query response time and energy consumption by reducing the routing path length.