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Overlay Multicast Optimization : IBM ILOG CPLEX

Kucharzak M., Zydek D., Poźniak-Koszałka I.

International Journal of Electronics and Telecommunications

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2012

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Vol. 58, No. 4

381-388

EN

IBM ILOG CPLEX Optimization Studio delivers advanced and complex optimization libraries that solve linear programming (LP) and related problems, e.g., mixed integer. Moreover, the optimization tool provides users with its Academic Research Edition, which is available for teaching and noncommercial research at no-charge. This paper describes the usage of CPLEX C++ API for solving linear problems and, as an exhaustive example, optimization of network flows in overlay multicast is taken into account. Applying continuous and integral variables and implementing various constraints, including equations and inequalities, as well as setting some global parameters of the solver are presented and widely explained.

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Performance evaluation of multicast overlay routing protocols

Stachowiak K., Pawlak T., Piechowiak M.

Image Processing & Communications

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2012

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Vol. 17, no. 1-2

19--31

EN

For almost three decades the multicast communication has been a subject of a dynamic research. It came to the world of the packet switching networks rather late and still has not becorne a fist class citizen of the Internet, yet the demand for such services is growing and thus the relevant technologies evolve persistently providing increasing quality and availability of the means of the group communication. The overlay approach to the multicast is an application layer realization which came to life due to certain deficiencies at the lower layers. In general the gain from using multicast for group communication instead of duplicated unicast links is that we avoid sending the same data many times through a single link. Such gain may he achieved with the use of the router level mulitcast solution. The overlay solutions tend to approach his level of efficiency with a different degree of success. Therefore one of the main characteristics that is interesting when evaluating a particular overlay protocol- is how well does it achieve the aforementioned gain. There are several metrics that allow for objective comparison of protocols in this regard. However this is not the only point of view to provide a valuable evaluation of the multicast overlay solutions. One of the important as aspects of the modem group communication such as the IPTV or teleconferencing is the dynamic nature of the users' participation. A particular group may be joined and left by multiple users at a very frequent rate which is critical to the resources management as well as to maintaining the integrity of the abstract communication structure, e.g. a tree spanning all the participants. In such case two major classes of the evaluation criteria emerge: the statical and the dynamical ones. They're both very important and interdependent, however the means to measure them may differ significantly. In this article a wide variety of the multicast overlay protocols have been analysed and two of them have been chosen to be compared. The stress of the evaluation has heen put on the dynamic aspects of the multicast overlay protocols operation.

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Modelling of Minimum Cost Overlay Multicast Tree in Two Layer Networks

Kucharzak M., Walkowiak K.

International Journal of Electronics and Telecommunications

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2011

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Vol. 57, No. 3

317-322

EN

Multicast realises the data delivering to a group of destinations simultaneously while using the minimum network resources. The first implementation of multicasting has been built using specialized multicast routers and is well known as IP Multicast. Such a network comprises some drawback including complex addressing and routing scheme, it requires the deployment of special routers that are rather expensive and finally, there has not been proposed a reasonable business model regarding cross-providers multicast realization. Thereby, for the past few years, a new interest in delivering multicast traffic has arisen and some multicast systems defined for end-hosts overlay network have been successfully proposed. Overlay multicast implements a multicast technique at the top of computer networks and creates a virtual topology of clients which duplicate packets and maintain a multicast structure. This overlay structure forms an independent layer with logical links between the nodes without the knowledge about the underlaying topology. In the work we take a look at flow cost minimization of multicast stream in a system which combines the advantages of overlays and underlaying network awareness. This papers presents three independent linear-based models aimed at optimization of multicast tree topology and its network level unicast realization. The proposed formulations can be applied for deriving either lower bound of flows costs in existing systems or for designing new cooperative multilayer protocols for effective multicast transmission.