• The KIPS Transactions:PartC
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• v.11C no.4
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• pp.419-428
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• 2004

Due to the deployment problem of the IP Multicast service, the Application Layer Multicast (or Overlay Multicast) has appeared as an alter-native of the If Multicast. However, even though plenty of the Application Layer Multicast (ALM) Protocols were designed and their applications were developed according to the diverse requirements of each multicast service, researches on the ALM Protocols are focused on only a protocol design or an efficient multicast group management algorithm. And there is little effort to provide a unified guideline for development of the ALM Protocols and provide an environment for running multiple protocols simultaneously in a system. In this paper, we propose socket APIs to be a reference in developing new ALM Protocols which enables a system to support multiple protocols in a system with other ALM Protocols and which gives an environment to support efficient protocol management.

• The KIPS Transactions:PartB
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• v.12B no.6 s.102
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• pp.685-690
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• 2005

Recently, studies for effective multimedia data delivery have been widely performed. Among those researches, internet broadcasting is a technology to transmit various multimedia contents to variety of costumers on the internet simultaneously. To deliver large scale multimedia data such as internet broadcasting, efficient data delivery method is required. Therefore, technologies based on the overlay multicast of application larger multicast application are actively studied as an alternative for multicast overcoming shortcoming of uni-cast based technologies, which we one to one transmission methods. In this paper, we classify and study on the overlay multicasting for internet broadcasting, which can be implemented by application programs without modification in physical layer of the internet.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.10 no.7
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• pp.1229-1236
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• 2006

Group oriented multicast service is a prerequisite for the current application system for remote lecture and customer service. IP multicast is used to be generally accepted as an internet standard. IP multicast which is designed to support network based replication model can efficiently use host and network resource, however it has some weak points that it has to support IP multicast in the internet by adding multicast-capable internet infrastructure such as router and is vulnerable to security by using public IP address for group identifier. Therefore we propose the trigger based application level multicast model that can enhance both scalability and security by separating the functions, which send and receive message to solve these problems. Our suggested model is expected to ensure the promotion of quality of service and reliability.

• Proceedings of the IEEK Conference
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• 1999.06a
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• pp.118-121
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• 1999

Multicast addresses cannot be permanently assigned to particular application or group combination, but need to be available for re-use. So, this requires a dynamic multicast address allocation and release mechanism. For a dynamic multicast address allocation and release mechanism, we must consider low blocking probability, low delay, low control traffic overhead. In this paper, we suggest a efficient dynamic multicast address allocation and release mechanism based on the multicast scope

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2006.05a
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• pp.1609-1615
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• 2006

Overlay multicast technique is an effective way as an alternative to IP multicast. Traditional IP multicast is not widely deployed because of the complexity of IP multicast technology and lack of application. But overlay multicast can be easily deployed by effectively reducing complexity of network routers. Because overlay multicast resides on top of densely connected IP network, In case of multimedia streaming service over overlay multicast tree, real-time data is sensitive to end-to-end delay. Therefore, moderate algorithm's development to this network environment is very important. In this paper, we are interested in minimizing maximum end-to-end delay in overlay multicast tree. The problem is formulated as a degree-bounded minimum delay spanning tree, which is a problem well-known as NP-hard. We develop tabu search heuristic with intensification and diversification strategies. Robust experimental results show that is comparable to the optimal solution and applicable in real time

• Journal of Korea Society of Industrial Information Systems
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• v.14 no.4
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• pp.49-56
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• 2009

Recently, studies for effective multimedia contents delivery have been widely performed in the multimedia streaming area. Overlay multicast, which can be implemented in the application layer, is method to transmit multimedia content's effectively. The Overlay multicast method can implement multicast transmission without changing the physical layer, and it has the characteristic that the application method can be diversify according to the algorithm. This paper has proposed the backup path construction method of overlay multicast for stabilized multimedia contents transmission. The proposed method can construct a backup path with the minimum searching method for guaranteed QoS(Quality of Service) and in overlay multicast so a fast and simple backup path can be constructed.

• Journal of KIISE:Computing Practices and Letters
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• v.14 no.2
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• pp.181-185
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• 2008

Layered video multicast such as RLM Receiver-driven layered multicast) is a premising technique for delivering streaming video to a set of heterogeneous receivers over ALM(Application Layer Multicast) as well as over IP multicast. However, this approach may suffer from unnecessary fluctuation of video quality due to overlapped and failed join-experiments. Though a shared teaming scheme was introduced to resolve these problems, it may cause high control overhead and slow convergence problem when used with ALM. In this paper, we propose a new shared learning scheme for ALM-based layered video multicast which reduces control overhead and convergence latency while keeping the number of fluctuation reasonably small. The simulation results show that the proposed scheme performs better than an ALM-based layered video multicast with shared learning in terms of control overhead and convergence latency.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.12
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• pp.3117-3132
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• 2012

The tree topology in multicast systems has high transmission efficiency, low latency, but poor resilience to node failures. In our work, some nodes are selected as backbone nodes to construct a tree-like core overlay. Backbone nodes are reliable enough and have strong upload capacity as well, which is helpful to overcome the shortcomings of tree topology. The core overlay is organized into a spanning tree while the whole overlay is of mesh-like topology. This paper focuses on improving the performance of the application-layer multicast overlay by optimizing the core overlay which is periodically adjusted with the proposed optimization algorithm. Our approach is to construct the overlay tree based on the out-degree weighted reliability where the reliability of a node is weighted by its upload bandwidth (out-degree). There is no illegal solution during the evolution which ensures the evolution efficiency. Simulation results show that the proposed approach greatly enhances the reliability of the tree-like core overlay systems and achieves shorter delay simultaneously. Its reliability performance is better than the reliability-first algorithm and its delay is very close to that of the degree-first algorithm. The complexity of the proposed algorithm is acceptable for application. Therefore the proposed approach is efficient for the topology optimization of a real multicast overlay.

• Proceedings of the Korean Information Science Society Conference
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• 2002.10e
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• pp.352-354
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• 2002

Explicit multicast 는 narrowcast 기술의 일종으로써 소수의 참여자가 참가하는 다수의 멀티캐스트 그룹을 지원하는데 효과적인 멀티캐스트 프로토콜이다. 기존의 멀티캐스트기술에 비해 Explicit multicast 는 세션별 정보를 유지하고 있지 않기 때문에 네트워크 대역폭을 절약할 수 있고 확장성에 대한 강점을 가지고 있다. 본 연구에서는 Explicit multicast 프로토콜의 특징들을 분석해 보고 Explicit multicast 프로토콜을 지원하는 라우터를 Linux 기반 플랫폼에서 동작하도록 구현하여 Explicit multicast 실험 네트워크를 구축한다. 또한 Explicit multicast 프로토콜 응용프로그램을 개발하여 구축된 Explicit multicast 네트워크와 연동시켜 프로토콜의 동작을 확인한다. 이러한 개발 및 실험 결과를 바탕으로 향후 Explicit multicast 프로토콜이 효과적으로 사용되기 위한 개선점들을 제안한다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.12
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• pp.4343-4355
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• 2014

Multicast group communication has many advantages in data centers and thus is widely used by many applications. It can efficiently reduce the network traffic and improve the application throughput. For the multicast application in data centers, an essential problem is how to find a minimal multicast tree, which has been proved to be NP-hard. In this paper, we propose an approximation tree-building method for the minimal multicast problem, named HD（Hamming Distance）-based multicast tree. Consider that many new network structures have been proposed for data centers. We choose three representative ones, including BCube, FBFLY, and HyperX, whose topological structures can be regarded as the generalized hypercube. Given a multicast group in BCube, the HD-based method can jointly schedule the path from each of receiver to the only sender among multiple disjoint paths; hence, it can quickly construct an efficient multicast tree with the low cost. The experimental results demonstrate that our method consumes less time to construct an efficient multicast tree, while considerably reduces the cost of the multicast tree compared to the representative methods. Our approach for BCube can also be adapted to other generalized hypercube network structures for data centers after minimal modifications.