Scalable IP multicast for many very small groups with many senders and its application to mobility

We consider the problem of multicast routing in a large single domain network with a very large number of multicast groups with small number of receivers. Such a case occurs, for example, when multicast addresses are statically allocated to mobile terminals, as a mechanism to manage Internet host mobility. For such networks, existing dense or sparse mode multicast routing algorithms do not scale well with the number of multicast groups. We propose an alternative solution called Distributed Core Multicast (DCM) that is based on an extension of the centre-based tree approach. We also describe how our approach can be used to support mobile terminals

Analysis domain model for shared virtual environments

The field of shared virtual environments, which also encompasses online games and social 3D environments, has a system landscape consisting of multiple solutions that share great functional overlap. However, there is little system interoperability between the different solutions. A shared virtual environment has an associated problem domain that is highly complex raising difficult challenges to the development process, starting with the architectural design of the underlying system. This paper has two main contributions. The first contribution is a broad domain analysis of shared virtual environments, which enables developers to have a better understanding of the whole rather than the part(s). The second contribution is a reference domain model for discussing and describing solutions - the Analysis Domain Model

Protocols for collaborative applications on overlay networks.

Third, we address the limitations of traditional multicasting models. Towards this, we propose a model where a source node has different switching time for each child node and the message arrival time at each child depends on the order in which the source chooses to send the messages. This model captures the heterogeneous nature of communication links and node hardware on the overlay network. Given a multicast tree with link delays and generalized switching delay vectors at each non-leaf node, we provide an algorithm which schedules the message delivery at each non-leaf node in order to minimize the delay of the multicast tree.First, we consider the floor control problem wherein the participating users coordinate among themselves to gain exclusive access to the communication channel. To solve the floor control problem, we present an implementation and evaluation of distributed Medium Access Control (MAC) protocols on overlay networks. As an initial step in the implementation of these MAC protocols, we propose an algorithm to construct an efficient communication channel among the participating users in the overlay network. We also show that our implementation scheme (one of the first among decentralized floor control protocols) preserves the causal ordering of messages.Our research is focused on the development of algorithms for the construction of overlay networks that meet the demands of the distributed applications. In addition, we have provided network protocols that can be executed on these overlay networks for a chosen set of collaborative applications: floor control and multicasting. Our contribution in this research is four fold.Fourth, we address the problem of finding an arbitrary application designer specific overlay network on the Internet. This problem is equivalent to the problem of subgraph homeomorphism and it is NP-Complete. We have designed a polynomial-time algorithm to determine if a delay constrained multicasting tree (call it a guest) can be homeomorphically embedded in a general network (call it a host). A delay constrained multicasting tree is a tree wherein the link weights correspond to the maximum allowable delay between the end nodes of the link and in addition, the link of the guest should be mapped to a shortest path in the host. Such embeddings will allow distributed application to be executed in such a way that application specific quality-of-service demands can be met. (Abstract shortened by UMI.)Second, we address the problem of designing multicasting sub-network for collaborative applications using which messages are required to arrive at the destinations within a specified delay bound and all the destinations must receive the message from a source at 'approximately' the same time. The problem of finding a multicasting sub-network with delay and delay-variation bound has been proved to be NP-Complete in the literature and several heuristics have been proposed

Managing dynamic groups in QoS and overlay multicasting

Multicasting has been the most popular mechanism for supporting group communication, wherein group members communicate through a multicast data distribution tree that spans all the members of the group. In a dynamic multicast session, members join/leave the group using graft/prune mechanisms, based on locally optimal paths, which would eventually degenerate the quality of the multicast tree. Therefore, efficient mechanisms need to be invoked periodically to maintain the cost of the multicast tree near optimal. However, tree maintenance would result in service disruption for the session. Therefore, there exists a trade-off between minimizing tree cost and minimizing service disruption. The goal of this dissertation is to develop and analyze a set of efficient tree maintenance techniques that aim to balance this tradeoff in QoS and overlay multicasting. To achieve this goal, the dissertation makes three key contributions. First, the design of scalable protocols, viz. tree migration and tree evolution, for maintaining QoS multicast trees. Second, the design of an efficient strategy, called partial protection approach, and its implementation methods for member join problem with path reliability being a QoS constraint. Third, the design of an efficient tree maintenance algorithm, based on the idea of mesh-tree interactions, for end-system based overlay multicasting. The proposed tree maintenance solutions have been evaluated and analyzed through a combination of simulation and analytical studies. The studies show that the proposed solutions indeed achieve a good balance between tree cost and service disruption competitively

Quality of service (QoS) support for multimedia applications in large-scale networks

This dissertation studied issues pertaining to QoS provision for multimedia applications at the application layer. We initially studied Internet routing pathology and Internet routing stability by repeating experimental and analytical methods conducted by Paxson in 1996. No similar study was done in recent years. Our findings show that routing behavior of the Internet in 2006 are different from those reported in 1996 in some important aspects. Second, we investigated different stochastic models (e.g. self-similar processes, Auto-Regressive Integrated Moving-Average (ARIMA)) in order to find a suitable model that describes available bandwidth over time of an end-to-end path between two Internet hosts. Our finding of the suitable model is beneficial to predicting of future values of available bandwidth along an end-to-end path. To the best of our knowledge, no similar study was conducted. Third, we designed and evaluated a new path monitoring algorithm inferring available bandwidth of an end-to-end path without monitoring all the paths to minimize monitoring overhead. Our algorithm does not rely on underlying network-layer topology information as required in topology-aware path monitoring techniques. Finally, to complement the above study, we introduced our multicast protocol named core-set routing for transmitting multimedia data from a set of senders to a set of receivers, taking QoS into account. The protocol is suitable for interactive multi-sender multimedia applications such as video conferencing and network gaming

Learning algorithms for the control of routing in integrated service communication networks

There is a high degree of uncertainty regarding the nature of traffic on future integrated service networks. This uncertainty motivates the use of adaptive resource allocation policies that can take advantage of the statistical fluctuations in the traffic demands. The adaptive control mechanisms must be 'lightweight', in terms of their overheads, and scale to potentially large networks with many traffic flows. Adaptive routing is one form of adaptive resource allocation, and this thesis considers the application of Stochastic Learning Automata (SLA) for distributed, lightweight adaptive routing in future integrated service communication networks. The thesis begins with a broad critical review of the use of Artificial Intelligence (AI) techniques applied to the control of communication networks. Detailed simulation models of integrated service networks are then constructed, and learning automata based routing is compared with traditional techniques on large scale networks. Learning automata are examined for the 'Quality-of-Service' (QoS) routing problem in realistic network topologies, where flows may be routed in the network subject to multiple QoS metrics, such as bandwidth and delay. It is found that learning automata based routing gives considerable blocking probability improvements over shortest path routing, despite only using local connectivity information and a simple probabilistic updating strategy. Furthermore, automata are considered for routing in more complex environments spanning issues such as multi-rate traffic, trunk reservation, routing over multiple domains, routing in high bandwidth-delay product networks and the use of learning automata as a background learning process. Automata are also examined for routing of both 'real-time' and 'non-real-time' traffics in an integrated traffic environment, where the non-real-time traffic has access to the bandwidth 'left over' by the real-time traffic. It is found that adopting learning automata for the routing of the real-time traffic may improve the performance to both real and non-real-time traffics under certain conditions. In addition, it is found that one set of learning automata may route both traffic types satisfactorily. Automata are considered for the routing of multicast connections in receiver-oriented, dynamic environments, where receivers may join and leave the multicast sessions dynamically. Automata are shown to be able to minimise the average delay or the total cost of the resulting trees using the appropriate feedback from the environment. Automata provide a distributed solution to the dynamic multicast problem, requiring purely local connectivity information and a simple updating strategy. Finally, automata are considered for the routing of multicast connections that require QoS guarantees, again in receiver-oriented dynamic environments. It is found that the distributed application of learning automata leads to considerably lower blocking probabilities than a shortest path tree approach, due to a combination of load balancing and minimum cost behaviour

Novel multicast protocols in ad-hoc networks

Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal

Rendezvous Point Selection In Multicast Networks

Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2005Thesis (M.Sc.) -- İstanbul Technical University, Institute of Science and Technology, 2005Bu çalışmada, günümüzde kullanılan seyrek tarzlı çoklu aktarım algoritmalarının bir eksiği olan ve dinamik üyelere sahip çoklu aktarım gruplarında daha belirgin olarak gözlemlenen çoklu gönderim ağacına bağlı servis kalitesinde düşme problemi üzerinde durulmaktadır. Günümüzde kullanılan seyrek tarzlı çoklu gönderim algoritmalarında, merkez düğüm seçilmesi yönetimsel olarak yapılmaktadır ve durağan bir seçim yöntemidir. Bu nedenle, zamanla çoklu aktarım grubuna yeni alıcılar ve kaynaklar üye olduklarında ya da ayrıldıklarında, yönetimsel olarak seçilen merkez düğümlü çoklu aktarım ağaçlarında servis kalitesi düşer. Beklenen servis kalitesine tekrar ulaşabilmek için, yeni bir merkez düğüm seçilmeli ve çoklu gönderim ağacı yeni bulunan merkez düğüme göre oluşturulmalıdır. Bu çalışmada, var olan protokollerden PIM-SM çoklu gönderim protokolü ile merkez düğümün dinamik değişmesine olanak veren SCMP çoklu gönderim protokolü incelenmiş, birbirleriyle karşılaştırılmış ve merkez düğümün yer değiştirilmesinin sağladığı avantajlar ve dezavantajlar farklı tipteki ağlar ve çoklu aktarım senaryoları üzerinde denenerek belirlenmeye çalışılmıştır. Ayrıca, yapılan bu çalışma sırasında esnek bir çoklu gönderim senaryo üreteci geliştirilmiştir.In this study, the focus is on the problem of the degradation of the multicast trees used in sparse mode multicast protocols, which have dynamic members, due to inefficiency in the location of the core (rendezvous) router as time proceeds. In sparse mode multicast protocols, the rendezvous point is chosen administratively and it is a static selection method unresponsive to the changes in the network dynamics. Therefore, when new sources or receivers join/leave the multicast group by time, the quality of service(QoS) provided by the multicast tree degrades. A better rendezvous point should be selected to prevent this problem and a new multicast tree must be reconstructed rooted at the new RP. In this study, PIM-SM protocol,with static RP, is compared with SCMP protocol which enables the RP to be changed. The advantages and the disadvantages of dynamic RP relocation process is investigated for different type of networks and multicast scenarios. During this work, a flexible multicast scenario generator is developed and used.Yüksek LisansM.Sc