• The KIPS Transactions:PartA
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• v.13A no.1 s.98
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• pp.1-10
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• 2006

For efficient searching in unstructured peer-to-peer systems, random walk was proposed and several replication methods have been studied to compensate for the random walk's low query success rate. This paper proposes an efficient replication scheme that improves the accuracy and speed of queries and reduces the cost by minimizing the number of replicas and by utilizing caches. In this scheme, hub nodes store only content's caches, and one of their neighbors stores the replica. By determining hubs with only limited and local information, we can adaptively generate caches and replicas in dynamic peer-to-peer networks.

• Proceedings of the Korean Information Science Society Conference
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• 2006.06d
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• pp.271-273
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• 2006

초기의 비구조적인 피어-투-피어 방식은 플러딩(flooding) 방식의 검색 기법을 사용하는데, 이 기법은 통신비용이 매우 많이 소요되어 비효율적이다. 따라서 효율적인 검색 기법으로 임의 경로(random walk) 검색 방식이 제안되었다. 이 검색 기법은 메시지가 임의로 노드를 이동하기 때문에, 검색의 성공률이 낮다. 이를 보완하기 위하여 효율적인 복제기법이 요구된다. 현재 나와 있는 복제 기법은 여러 방법이 있으나, 모두 통신에 고비용을 요구한다. 따라서 복제 기법에서는 통신비용을 최소화하는 효율적인 복제 기법이 필요하다. 본 논문에서는 캐시를 사용하여 직접적인 데이터 통신비용을 최대로 줄이는 한편, 복제를 질의가 많이 도착하는 곳에 위치시켜 검색률의 저하를 막고, 잘못된 캐시 관리 기법을 통해 동적인 환경에서도 잘못된 캐시로 인한 검색의 실패를 최소할 수 있는 기법을 제안한다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.4C
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• pp.451-457
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• 2006

A peer-to-peer(P2P) network is inherently vulnerable to malicious attacks from participating peers because of its open, flat, and autonomous nature. This paper addresses the problem of effectively defending from active attacks of malicious peers at bootstrapping phase and at online phase, respectively. We propose a secure membership handling protocol to protect the assignment of ID related things to a newly joining peer with the aid of a trusted entity in the network. The trusted entities are only consulted when new peers are joining and are otherwise uninvolved in the actions of the P2P networks. For the attacks in online phase, we present a novel message structure applied to each message transmitted on the P2P overlay. It facilitates the detection of message alteration, replay attack and a message with wrong information. Taken together, the proposed techniques deter malicious peers from cheating and encourage good peers to obey the protocol of the network. The techniques assume a basic P2P overlay network model, which is generic enough to encompass a large class of well-known P2P networks, either unstructured or not.

• Journal of KIISE:Information Networking
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• v.35 no.4
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• pp.268-281
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• 2008

It is difficult to construct streaming services based on the overlay networks without any loss of scalability. DONet is one of the most representative streaming overlay network protocols without managing any specific structure. Since DONet does not support the nodes on private networks, it can be considered that the performance of the overlay is not the best. Hole Punching is one of the famous techniques participating the nodes on private networks to streaming overlay networks by using a rendezvous server. However, using only a single rendezvous server cannot be suggested in P2P environment, because it can cause problems in terms of scalability and so on. In this paper, we propose DONet-p, an extension of DONet with Distributed Hole Punching techniques. It supports the nodes on private networks without toss of scalability. The experimental results show the better performance and scalability than DONet with a minimum overhead for additional control messages.