• Title, Summary, Keyword: Distributed Hash Table

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Distributed Hash Table based Service Discovery in Mobile Ad Hoc Network (모바일 애드 혹 네트워크에서 분산 해쉬 테이블 기반의 서비스 탐색 기법)

  • Jung, Jae-Hoon;Lee, Seung-Hak;Kim, Nam-Gi;Yoon, Hyn-Soo
    • Journal of KIISE:Information Networking
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    • v.35 no.1
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    • pp.91-97
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    • 2008
  • In order to get a desired service in such environments, we need a service discovery method for discovering a device providing that service. In this paper, we propose a service discovery protocol which is based on DHTs (Distributed Hash Tables) to solve these problems. Our protocol is scalable since it does not require a central lookup server and does not rely on multicast or flooding. Simulation results show that our protocol is scalable and outperforms existing service discovery protocols.

A Geographic Distributed Hash Table for Virtual Geographic Routing in MANET (MANET에서 가상 위치 기반 라우팅을 위한 지역 분산 해쉬 테이블 적용 방법)

  • Ko, Seok-Kap;Kim, Young-Han
    • Journal of the Institute of Electronics Engineers of Korea TC
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    • v.45 no.12
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    • pp.58-65
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    • 2008
  • This paper presents a new geographic distributed hash table (GDHT) for MANETs or Mesh networks, where virtual geographic protocol is used. In previous wort GDHT is applied to a network scenario based on two dimensional Cartesian coordinate system. Further, logical data space is supposed to be uniformly distributed. However, mobile node distribution in a network using virtual geographic routing is not matched to data distribution in GDHT. Therefore, if we apply previous GDHT to a virtual geographic routing network, lots of DHT data are probably located at boundary nodes of the network or specific nodes, resulting in long average-delay to discover resource (or service). Additionally, in BVR(Beacon Vector Routing) or LCR(Logical Coordinate Routing), because there is correlation between coordinate elements, we cannot use normal hash function. For this reason, we propose to use "geographic hash function" for GDHT that matches data distribution to node distribution and considers correlation between coordinate elements. We also show that the proposed scheme improves resource discovery efficiently.

A Study on the Group Routing Algorithm in DHT-based Peer-to-Peer System (DHT 기반 P2P 시스템을 위한 그룹 라우팅 알고리즘에 관한 연구)

  • Park, Yong-Min
    • Journal of the Korea Society of Computer and Information
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    • v.17 no.12
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    • pp.111-120
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    • 2012
  • As the P2P System is a distributed system that shares resources of nodes that participate in the system, all the nodes serve as a role of server and client. Currently, although systematic, structured P2P systems such as Chord, Pastry, and Tapestry were suggested based on the distributed hash table, these systems are limited to $log_2N$ for performance efficiency. For this enhanced performance efficiency limited, the article herein suggests group routing algorithm. The suggested algorithm is a node-to-group routing algorithm which divides circular address space into groups and uses a concept of pointer representing each group, which is an algorithm where routing is performed based on pointer. To evaluate algorithm performance, a comparative analysis was conducted on average hops, routing table size, and delayed transmission for chord and routing, a signature algorithm in P2P systems. Therefore, enhanced performance is verified for comparative items from the simulation results.

The Design of Proxy Peer Algorithm based on DHT for Effective Resource Searching on JXTA Network Environments (JXTA 네트워크 환경에서 효율적인 자원 검색을 위한 DHT 기반프락시 피어 알고리즘 설계)

  • Lee, Gwang;Lee, Joon
    • Journal of the Korea Institute of Information and Communication Engineering
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    • v.11 no.8
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    • pp.1486-1492
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    • 2007
  • Searching distributed resources efficiently is very important in distributed computing environments like P2P. But distributed resource searching may have system overheads and take a lot of time in proportion to the searching number, because distributed resource searching has to circuit many peers for searching information. In this paper, we design a proxy peer algorithm based on DHT(Distributed Hash Table) for efficient distributed resource searching in JXTA network environments. By containing the rendezvous information in proxy peer and searching a rendezvous peer firstly which has higher hit ratio, we can reduce the searching number and minimize system overheads.

An Improved Signature Hashing Algorithm for High Performance Network Intrusion Prevention System (고성능 네트워크 침입방지시스템을 위한 개선된 시그니처 해싱 알고리즘)

  • Ko, Joong-Sik;Kwak, Hu-Keun;Wang, Jeong-Seok;Kwon, Hui-Ung;Chung, Kyu-Sik
    • The KIPS Transactions:PartC
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    • v.16C no.4
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    • pp.449-460
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    • 2009
  • The signature hashing algorithm[9] provides the fast pattern matching speed for network IPS(Intrusion Prevention System) using the hash table. It selects 2 bytes from all signature rules and links to the hash table by the hash value. It has an advantage of performance improvement because it reduces the number of inspecting rules in the pattern matching. However it has a disadvantage of performance drop if the number of rules with the same hash value increases when the number of rules are large and the corelation among rules is strong. In this paper, we propose a method to make all rules distributed evenly to the hash table independent of the number of rules and corelation among rules for overcoming the disadvantage of the signature hashing algorithm. In the proposed method, it checks whether or not there is an already assigned rule linked to the same hash value before a new rule is linked to a hash value in the hash table. If there is no assigned rule, the new rule is linked to the hash value. Otherwise, the proposed method recalculate a hash value to put it in other position. We implemented the proposed method in a PC with a Linux module and performed experiments using Iperf as a network performance measurement tool. The signature hashing method shows performance drop if the number of rules with the same hash value increases when the number of rules are large and the corelation among rules is strong, but the proposed method shows no performance drop independent of the number of rules and corelation among rules.

Implementation of a Flexible Peer-to-Peer Internet Telephony Service Using an Underlying DHT (유연성을 갖는 분산 해쉬 테이블 기반의 피어 투 피어 인터넷 텔레포니 서비스의 구현)

  • Lee, Ju-Ho;Kim, Jae-Bong;Jeong, Choong-Kyo
    • Journal of Industrial Technology
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    • v.26 no.B
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    • pp.199-206
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    • 2006
  • Internet telephony provides voice communication services with added flexibility for multimedia extension at a lower cost compared to traditional telephone systems. We implemented an internet telephony system as an overlay network without a centralized server, using a distributed hash table (DHT). Compared to the current server-based internet telephony system, our system is fault-tolerant, scalable, and can be flexible extended to various services and advanced to integrated service. To demonstrate the high flexibility of our DHT-based internet telephony system, we made our system cooperate with web servers. Web users can check up others' online stales and establish voice communication sessions to online users at a mouse click. This technology can be applied to more complex services such as multimedia messaging or video conference service.

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Rich Query Mechanism in DHT based P2P Network (DHT 기반 P2P 네트워크에서 Rich Query 매커니즘)

  • Son, Young-Sung;Kim, Hee-Jeong;Kim, Gyung-Seok
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • v.9 no.2
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    • pp.150-152
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    • 2005
  • 인터넷 상의 컴퓨팅 자원을 오버레이 네트워크를 구성하여 새로운 컴퓨팅 인프라를 구성하려는 연구가 분산 해쉬 테이블 (Distributed Hash Table) 방식의 Peer-to-Peer(P2P) 네트워크로 실현되고 있다. DHT 방식의 P2P 네트워크는 자원의 복제 및 공유하여 컴퓨팅 시스템 전반에 걸친 신뢰성과 결함감내 능력을 향상시키고 Exactly Matching Query에 장점이 있는 반면에 다중키 질의, 계층 질의 및 구간 질의와 같은 복합 질의(Rich Query) 제원에 문제점을 드러낸다. 이 논문에서는 DHT 기반의 P2P 네트워크에서 Rich Query 를 지원하기 위한 방법을 소개한다.

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Message Routing Mechanism using Network Topology Information in DHT based P2P Network (DHT 기반 P2P 네트워크에서 네트워크 토폴로지를 고려한 메시지 라우팅 매커니즘)

  • Son, Young-Sung;Kim, Hee-Jeong;Kim, Gyung-Seok
    • 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.

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DHT(Distributed Hash Table) 기반 P2P 오버레이 네트워크 보안 위협 분석

  • 권혁찬;나재훈;장종수
    • Review of KIISC
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    • v.15 no.6
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    • pp.60-67
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    • 2005
  • 올 9월 NGN2005에서는 2003년을 기점으로 하여 인터넷에서 가장 많은 트래픽을 차지하는 서비스가 P2P(Peer-to-Peer) 서비스라는 통계를 발표하였다. 실제로, 현재 수많은 사용자가 P2P 서비스를 이용하고 있으며 다양한 P2P 응용 및 구조에 대한 연구가 다소 활발히 진행되고 있는 상황이다. 최근에는 P2P 파일공유 응용분야에서 DHT(Distributed Hash Table) 기반의 오버레이 네트워크를 활용하고자 하는 일부 연구도 진행되고 있다. 이와 관련하여 본 고 에서는 DHT 기반 P2P 오버레이 네트워크를 구축하기 위한 기존의 방식들을 소개하고, 이에 대한 보안 위협을 분석하고자 한다.

Clustered Segment Index Scheme for P2P VOD Service on Virtual Mesh Overlay Network (가상 메시 오버레이 네트워크상에서의 P2P VOD 서비스를 위한 클러스터 세그먼트 인덱스 기법)

  • Lim, Pheng-Un;Choi, Hwang-Kyu
    • The Transactions of The Korean Institute of Electrical Engineers
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    • v.65 no.6
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    • pp.1052-1059
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    • 2016
  • Video-on-Demand(VoD) is one of the most popular media streaming which attracted many researchers' attention. VMesh is one of the most cited works in the field of the VoD system. VMesh is proposed to solve the problem of random seeking functionality. However, a large number of the DHT(Distributed Hash Table) searches in VMesh is sill the main problem which needs to be solved. In order to reduce the number of the DHT searches, the clustered segment index(CSI) scheme is proposed. In this scheme, the video segments are divided into clusters. The segment information of the video segments, which are clustered into the same cluster, are stored in the same clustered segment index that can be searched by using the hash key. Each peer also can request the required segments by using this clustered segment index. The experiment results show that the number of the DHT searches in the proposed scheme is less than that of VMesh even in case of peers leave and join the network or peers perform the fast forward/backward operations.