• Journal of the Institute of Electronics Engineers of Korea TC
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• v.43 no.6 s.348
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• pp.9-22
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• 2006

When the legacy multicast routing protocols are adopted in If-based mobile core networks, there are some problems such as traffic injection from unnecessary sources, traffic overhead by group management and router performance degradation by large amount of multicast session information. In this paper, we propose a stateless multicast mechanism which has no need to maintain multicast information for session status and reduces redundant network overhead for maintaining multicast tree. In addition interworking with IGMPv3 gets rid of traffic from unnecessary sources which have no registration from receivers. The operations of essential components including a gateway node for interworking with the legacy Internet multicast network, a gateway node for transparency to radio access network and a intermediate node in mobile core networks, are definitely defined and the proposed communication architecture is completed. Finally we evaluate and approve the performance of the proposed architecture by means of well-designed network simulation.

• Journal of Korea Society of Industrial Information Systems
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• v.8 no.3
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• pp.99-104
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• 2003

Ad-hoc is the wireless network and consists of moving Hosts in environments which don't have a network-based Frame. Because ad-hoc is considered as broadcast network and network which has useful benefits, multicast muting protocols have been studied on ad-hoc network For this work we scrutinized ad-hoc and multicast routing protocols presented in previous works. And we presents a protocol for Ad-hoc network.

• Proceedings of the Korean Information Science Society Conference
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• 2005.07a
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• pp.595-597
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• 2005

현재 IP 멀티캐스트의 도입의 지연으로, 기존의 유니캐스트 망 기반 멀티캐스트의 필요성이 대두되어 오버레이(Overlay) 멀티캐스트 관련 연구가 진행 중이다. 특히, 확장성 제공과 작은 오버헤드 등으로 효율적인 CBT(Core Based Trees) 기반의 오버레이 멀티캐스트에 대한 연구가 활발히 진행 중이다. 그러나 기존의 거리 매트릭(Metric) 기반의 CBT로 오버레이 트리를 구성하는 경우, 특정 라우터에 패킷이 집중되는 현상으로 인하여 혼잡이 발생하여 멀티캐스트 성능 저하뿐만 아니라 네트워크 전체 성능을 저하시킬 수 있다. 본 논문에서는 이를 해결칠기 위하여. 코어 노드를 기준으로 이웃하는 두 노드 간의 패킷 중계 방향성을 계산하는 알고리즘을 제안하고. 이 결과값을 이용하는 새로운 매트릭 기반의 CBT를 구성하고자 한다. 실험 결과, CBT 상의 자식 위치에 있는 종단 노드로 패킷을 중계하는 과정에서 중복되는 패킷 전송 경로를 최소화하여 CBT를 구성함으로써 특정 라우터에 집중되는 트래픽을 줄이거나 다른 라우터로 트래픽을 분산함으로써 혼잡 발생 가능을 낮추어 보다 안정적인 통신을 기대할 수 있다.

• Journal of KIISE:Computing Practices and Letters
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• v.6 no.2
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• pp.234-243
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• 2000

We design a modified network architecture with condsidering current Internet network model and traffic characteristics, and propose EDCBT(Enhanced Dispersed Core-based Tree) multicast routing protocol, which enhances scalabity, reliability, end-to-end delay and resource utilization EDBCT adopts bidirectional dispersed shared trees and manages both of intradomain and interdomain multicast trees for a multicast group. Each regional multicast tree is estabilshed from its core router and they are interconnected by the operation between border routers on edges of each regional network. As a result, interdomain multicast tree can be easily established. We introduce a new concept named RBTS(Region-based Tree Switching), which dramatically enhances QoS and network utilization. Finally, protocol performance and the effect of core router location are evaluated with MIL3 OPNet network simulator, in terms of end-to-end delay, packet loss and throughput.

• The KIPS Transactions:PartC
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• v.8C no.1
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• pp.60-67
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• 2001

Multicast Protocol for multimedia service on the Internet can be classified into two types, e.g., source based tree and shared tree according to difference of tree construction method. Shared tree based multicast is known to show outstanding results in the aspect of scalability than source based tree. Generally, There have been lots of researches on the method to satisfy QoS constraints through proper Rendezvous Point (RP) in the shared tree. In addition, as the multicast group members join and leave dynamically in the service time, RP of the shared tree should b be reselected for guranteeing Qos to new member, But, RP reselection method has not been considered generally as the solution to satisfy QoS C constraints. In this paper, new initial RP selection and RP reselection method are proposed, which utilize RTCP (Real Time Control Protocol) report packet fields. Proposed initial RP selection and RP reselection method use RTCP protocol which underlying multimedia application service So, the proposed method does not need any special process for collecting network information to calculate RP. New initial RP selection method s shows better performance than random and topology based one by 40-50% in simulation. Also, RP reselection method improves delay p performance by 50% after initial RP selection according to the member’s dynamicity.

• Proceedings of the IEEK Conference
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• 2003.07c
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• pp.2689-2692
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• 2003

본 논문에서는 향후 인터넷 환경에서 필수적인 요건이 될 수 있는 인터넷 멀티 캐스팅의 여러 프로토콜중 공유 트리 방식의 하나인 CBT 프로토콜에서 송신자와 수신자 사이의 경로 즉 비용을 줄이기 위해 기존의 코어 선택 알고리즘을 개선할 수 있는 알고리즘을 제안한다. CBT 프로토콜에서는 공유 트리의 구성이 코어 라우터를 중심으로 이루어지고 이 코어 라우터를 통해 그룹에 가입/ 데이터 전송/ 탈퇴 등이 이루어지게 되므로 코어 라우터의 선정은 전체적인 효율성 선정의 중요 요소가 된다. 여기서는 모든 노드의 전체 비용을 산출하여 가장 비용 요소가 적은 노드를 선정하는 알고리즘을 제안하며, 네트워크 시뮬레이터를 통해 사용율 및 평균비용을 기존 방식과 비교하여 그 결과에 대해서 논한다.

• Journal of KIISE:Information Networking
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• v.28 no.4
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• pp.586-601
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• 2001

We propose a mesh based multicast routing protocol referred to as HMMRP for ad-hoc networks. In HMMRP, a limited number of sources are selected as core sources, and the rest of the sources of a multicast group are connected to one of those core sources. The sources and the receivers of a multicast group are also connected through per source trees. In HMMRP, the data delivery mesh of a multicast group are composed of the nodes on these paths, and are reconfigured at regular intervals. Furthermore, each mesh member that lies on the paths between the sources and the core sources as well as be-tween the core sources and the receivers keeps checking if there is a symptom of mesh separation around itself. When a mesh member finds such symptom, it tries to patch itself to the mesh with a local flooding. As a result, the part of the data delivery mesh on those paths are kept connected with a lot higher probability than the rest of the data delivery mesh. That is, for a certain source receiver pair, it is very likely that at least there exists a data delivery path that route from the source to a core source and then to the receiver. Therefore, HMMRP may provide very high data delivery ratio without frequent entire data delivery mesh reconfiguration even when the nodal mobility is high. Simulation results show that HMMRP shows relatively little performance degradation with respect to mobility. Furthermore, the performance degradation with respect to mobility is even smaller when the size of the multicast group becomes larger.

• Journal of KIISE:Information Networking
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• v.29 no.5
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• pp.583-594
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• 2002

Assuring the security of group communications such as tole-conference and software distribution requires a common group key be shared among the legal members in a secure manner. Especially for large groups with frequent membership change, efficient rekey mechanism is essential for scalability. One of the most popular ways to provide sealable rekey is to partition the group into several subgroups. In this paper, we propose a two-layered key management scheme which combines DEP and CBT, a protocol in which subgroup manager cannot access the multicast data and another that has a multi-core, respectively. We also select sub-group key management protocols suitable for our structure and design new rekey protocols to exclude the subgroup managers from the multicast data. Compared to previous protocols based on CBT, our scheme provides forward secrecy, backward secrecy and scalability. This would reduce the number of encryption and decryption for a rekey message and would improve the efficiency number of rekey messages and the amount of information related to group members that group managers must maintain compared to DEP.