• Journal of Korea Multimedia Society
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• v.7 no.10
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• pp.1436-1442
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• 2004

A shared-based tree established by the Core Based Tree multicast routing protocol (CBT), the Protocol Independent Multicast Sparse-Mode(PIM-SM), or the Core-Manager based Multicast Routing(CMMR) is rooted at a center node called core or Rendezvous Point(RP). The routes from the core (or RP) to the members of the multicast group are shortest paths. The costs of the trees constructed based on the core and the packet delays are dependent on the location of the core. The location of the core may affect the cost and performance of the shared-based tree. In this paper, we propose three methods for selecting the set of candidate cores. The three proposed methods, namely, k-minimum average cost, k-maximum degree, k-maximum weight are compared with a method which select the candidate cores randomly. Three performance measures, namely, tree cost, mean packet delay, and maximum packet delay are considered. Our simulation results show that the three proposed methods produce lower tree cost, significantly lower mean packet delay and maximum packet delay than the method which selects the candidate cores randomly.

• 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.

• The KIPS Transactions:PartC
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• v.10C no.7
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• pp.885-890
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• 2003

The Core Base Tree (CBT) multicast routing architecture is a multicast routing protocol for the internet. The CBT establishes a single shared tree for a multicast connection. The shared tree Is rooted at a center node called core. The location of the core may affect the cost and performance of the CBT. The core placement method requires the knowledge of the network topology In this Paper, we propose a simple and effective method for selecting the core. This method requires the distance vector information. in addition, we used results that calculated sample correlation coefficient. And then we select suitable routing algorithm according to member's arrangement states in muliticast group. we select core node that have minimum average cost or PIM-SM protocol is selected. The performance of this method is compared with several other methods by extensive simulations (i.e mean delay, maximum delay, and total cost). Our results shows that this method for Selecting Core is very effective.

• ETRI Journal
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• v.22 no.1
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• pp.30-37
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• 2000

Existing tree construction mechanisms are classified into source-based trees and center-based trees. The source-based trees produce a source-rooted tree with a low delay. However, for the applications with multiple senders, the management overheads for routing tables and resource reservations are too high. The center-based trees are easy to implement and manage, but a priori configuration of candidate center nodes is required, and the optimization mature such as tree cost and delay is not considered. In this paper, we propose a new multicast tree building algorithm. The proposal algorithm basically builds a non-center based shared tree. In particular, any center node is not pre-configured. In the purposed algorithm, a multicast node among current tree nodes is suitably assigned to each incoming user: Such a node is selected in a fashion that tree cost and the maximum end-to-end delay on the tree are jointly minimized. The existing and proposed algorithms are compared by experiments. In the simulation results, it is shown that the proposed algorithm approximately provides the cost saving of 30% and the delay saving of 10%, compared to the existing approaches. In conclusion, we see that the cost and delay aspects for multicast trees can be improved at the cost of additional computations.

• Journal of KIISE:Information Networking
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• v.30 no.3
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• pp.424-436
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• 2003

In this paper, we propose the Centroid-based Backbone Core Tree(CBCT) generation algorithm for the shared tree-based IP multicasting. The proposed algorithm is based on the Core Based Tree(CBT) protocol. Despite the advantages over the source-based trees in terms of scalability, the CBT protocol still has the following limitations; first, the optimal core router selection is very difficult, and second, the multicast traffic is concentrated near a core router. The Backbone Core Tree(BCT) protocol, as an extension of the CBT protocol has been proposed to overcome these limitations of the CBT Instead of selecting a specific core router for each multicast group, the BCT protocol forms a backbone network of candidate core routers which cooperate with one another to make multicast trees. However, the BCT protocol has not mentioned the way of selecting candidate core routers and how to connect them. The proposed CBCT generation algorithm employs the concepts of the minimum spanning tree and the centroid. For the performance evaluation of the proposed algorithm, we showed the performance comparison results for both of the CBT and CBCT protocols.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.18 no.3
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• pp.425-438
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• 1993

Due to the producer-consumer dependency of shared variables, the potential parallelism embeded in the logic programming language has not been fully examined. The method proposed in this paper eliminates the dependency of shared variables by introducing number-sequenced variables in expanding an AND-OR proof tree. Basically, the execution of a logic program can be divided into two phases : expanding an AND-OR tree and proving the tree by matching facts with leaf nodes. In the course of the first phase, a set of number-sequenced variables are produced by expanding an AND-OR tree in the breadth-first searching. Based on the information of number-sequence, each of them is verified in the second phase in order to prove the tree. Consequently, the proposed algorithm can explore more parallelism without the dependency of shared variables.

• ETRI Journal
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• v.28 no.3
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• pp.329-336
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• 2006

This paper investigates the problem of protecting multicast sessions in mesh wavelength-division multiplexing (WDM) networks against single link failures, for example, a fiber cut in optical networks. First, we study the two characteristics of multicast sessions in mesh WDM networks with sparse light splitter configuration. Traditionally, a multicast tree does not contain any circles, and the first characteristic is that a multicast tree has better performance if it contains some circles. Note that a multicast tree has several branches. If a path is added between the leave nodes on different branches, the segment between them on the multicast tree is protected. Based the two characteristics, the survivable multicast sessions routing problem is formulated into an Integer Linear Programming (ILP). Then, a heuristic algorithm, named the adaptive shared segment protection (ASSP) algorithm, is proposed for multicast sessions. The ASSP algorithm need not previously identify the segments for a multicast tree. The segments are determined during the algorithm process. Comparisons are made between the ASSP and two other reported schemes, link disjoint trees (LDT) and shared disjoint paths (SDP), in terms of blocking probability and resource cost on CERNET and USNET topologies. Simulations show that the ASSP algorithm has better performance than other existing schemes.

• The KIPS Transactions:PartC
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• v.13C no.7 s.110
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• pp.905-912
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• 2006

Depending on the location of the rendezvous point (RP), the network efficiency is determined in the core based tree (CBT) or protocol independent multicast-sparse mode (PIM-5M) multicasting protocol to provide the multicast services based on the shared tree. In this paper, a new algorithm to allocate the RP using the estimated values of the total cost and the size(number of entries) of the routing tables is proposed for efficiently controlling the cost and the number of routing table entries. The numerical results show that the proposed algorithm reduces the total cost in 5.37%, and the size of routing tables in 13.35% as compared to the previous algorithm.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 1999.11a
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• pp.300-302
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• 1999

The multicast routing trees that have recently been proposed can be classified into three types: source-based trees, renter-based shared trees and non-renter based shared trees. In this paper, those multicast trees are compared and evaluated in term of the link costs and the maximum delay on the tree by experiments.

• The KIPS Transactions:PartC
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• v.10C no.1
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• pp.77-86
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• 2003

This paper describes the new method for Internet multicast routing protocols using MPLS (Multiprotocol Label Switching) networks. Internet multicast routing protocols are divided into three categories in terms if tree types and tree characteristics : a shortest path tree a shared tree and hybrid tree types. MPLS should support various multicast mechanisms because of extremely different IP multicast architectures, such as uni-/bi-directional link, Flooding/prune tree maintenance mechanism. the existence of different tree types with the same group, etc. There are so many problems over MPLS multicast that the solutions can't be easily figured out. In this Paper, we make a few assumptions on which the solutions of IP multicast routing protocols over MPLS networks are given. A broadcasting label is defined for the shortest path tree types. Cell interleaving problems of the shared tree types is solved by using block-based transmission mechanism. Finally, the existing hybrid-type multicast routing protocol is reasonably modified Shortest Path tree type to support MPLS multicast. It has been shown that these modifications give better performance (transmission delay) than the orignal method.