A bridging-based solution for efficient multicast support in wireless mesh networks

Proceedings of: The 34th Annual IEEE Conference on Local Computer Networks (LCN 2009), October 20-23, 2009, Zurich, SwitzerlandWireless mesh networking is a promising, cost effective and efficient technology for realizing backhaul networks supporting high quality services. In such networks, multicast data are transmitted blindly without any mechanism protecting data from loss, ensuring data reception, and optimizing channel allocation. The multicast services may undergo, then, very high data loss ratio which is exacerbated with the number of hops. In this paper, we propose a Reliable Multicast Distribution System (RMDS) to optimize multicast packets transmission in bridged networks. Relying on a modification of the IGMP snooping protocol, RMDS enables reliable services provisioning support in common wireless mesh networks. In particular, RMDS only exploits the local knowledge of a particular node to compute the multicast tree, which significantly reduces the signalling overhead in comparison with network layer and overlay solutions. Simulation results elucidate that RMDS optimizes resources’ allocation by reducing significantly the network load, the media access delay and the data drop rate compared to the classical approach, which is based on the combination of spanning tree algorithm and IGMP snooping protocol.European Community's Seventh Framework ProgramPublicad

A note on the data-driven capacity of P2P networks

We consider two capacity problems in P2P networks. In the first one, the nodes have an infinite amount of data to send and the goal is to optimally allocate their uplink bandwidths such that the demands of every peer in terms of receiving data rate are met. We solve this problem through a mapping from a node-weighted graph featuring two labels per node to a max flow problem on an edge-weighted bipartite graph. In the second problem under consideration, the resource allocation is driven by the availability of the data resource that the peers are interested in sharing. That is a node cannot allocate its uplink resources unless it has data to transmit first. The problem of uplink bandwidth allocation is then equivalent to constructing a set of directed trees in the overlay such that the number of nodes receiving the data is maximized while the uplink capacities of the peers are not exceeded. We show that the problem is NP-complete, and provide a linear programming decomposition decoupling it into a master problem and multiple slave subproblems that can be resolved in polynomial time. We also design a heuristic algorithm in order to compute a suboptimal solution in a reasonable time. This algorithm requires only a local knowledge from nodes, so it should support distributed implementations. We analyze both problems through a series of simulation experiments featuring different network sizes and network densities. On large networks, we compare our heuristic and its variants with a genetic algorithm and show that our heuristic computes the better resource allocation. On smaller networks, we contrast these performances to that of the exact algorithm and show that resource allocation fulfilling a large part of the peer can be found, even for hard configuration where no resources are in excess.Comment: 10 pages, technical report assisting a submissio

Deterministic Formulization of End-to-End Delay for Multicast Systems

End-System multicasting (ESM) is a promising application-layer scheme that has been recently proposed for implementing multicast routing in the application layer as a practical alternative to the IP multicasting. Moreover, ESM is an efficient application layer solution where all the multicast functionality is shifted to the end users. However, the limitation in bandwidth and the fact that the message needs to be forwarded from host-to-host using unicast connection, and consequently incrementing the end-to-end delay of the transmission process, contribute to the price to pay for this new approach. Therefore, supporting high-speed real-time applications such as live streaming multimedia, videoconferencing, distributed simulations, and multiparty games require a sound understanding of these multicasting schemes such as IP multicast and ESM and the factors that might affect the end-user requirements. In this paper, we present both the analytical and the mathematical models for formalizing the end-to-end delay efficiency of both IP and ESM multicast systems. For the sake of the experimental verifications of the proposed models, simulation results are presented in this paper. Finally, the proposed formulization can be used to design and implement a more robust and efficient multicast systems for the future networks

A Framework for Realistic and Systematic Multicast Performance Evaluation

Previous multicast research often makes commonly accepted but unverifed assumptions on network topologies and group member distribution in simulation studies. In this paper, we propose a framework to systematically evaluate multicast performance for different protocols. We identify a series of metrics, and carry out extensive simulation studies on these metrics with different topological models and group member distributions for three case studies. Our simulation results indicate that realistic topology and group membership models are crucial to accurate multicast performance evaluation. These results can provide guidance for multicast researchers to perform realistic simulations, and facilitate the design and development of multicast protocols

Exploiting Parallelism in the Design of Peer-to-Peer Overlays

Many peer-to-peer overlay operations are inherently parallel and this parallelism can be exploited by using multi-destination multicast routing, resulting in significant message reduction in the underlying network. We propose criteria for assessing when multicast routing can effectively be used, and compare multi-destination multicast and host group multicast using these criteria. We show that the assumptions underlying the Chuang-Sirbu multicast scaling law are valid in large-scale peer-to-peer overlays, and thus Chuang-Sirbu is suitable for estimating the message reduction when replacing unicast overlay messages with multicast messages. Using simulation, we evaluate message savings in two overlay algorithms when multi-destination multicast routing is used in place of unicast messages. We further describe parallelism in a range of overlay algorithms including multi-hop, variable-hop, load-balancing, random walk, and measurement overlay

Efficient service discovery in wide area networks

Living in an increasingly networked world, with an abundant number of services available to consumers, the consumer electronics market is enjoying a boom. The average consumer in the developed world may own several networked devices such as games consoles, mobile phones, PDAs, laptops and desktops, wireless picture frames and printers to name but a few. With this growing number of networked devices comes a growing demand for services, defined here as functions requested by a client and provided by a networked node. For example, a client may wish to download and share music or pictures, find and use printer services, or lookup information (e.g. train times, cinema bookings). It is notable that a significant proportion of networked devices are now mobile. Mobile devices introduce a new dynamic to the service discovery problem, such as lower battery and processing power and more expensive bandwidth. Device owners expect to access services not only in their immediate proximity, but further afield (e.g. in their homes and offices). Solving these problems is the focus of this research. This Thesis offers two alternative approaches to service discovery in Wide Area Networks (WANs). Firstly, a unique combination of the Session Initiation Protocol (SIP) and the OSGi middleware technology is presented to provide both mobility and service discovery capability in WANs. Through experimentation, this technique is shown to be successful where the number of operating domains is small, but it does not scale well. To address the issue of scalability, this Thesis proposes the use of Peer-to-Peer (P2P) service overlays as a medium for service discovery in WANs. To confirm that P2P overlays can in fact support service discovery, a technique to utilise the Distributed Hash Table (DHT) functionality of distributed systems is used to store and retrieve service advertisements. Through simulation, this is shown to be both a scalable and a flexible service discovery technique. However, the problems associated with P2P networks with respect to efficiency are well documented. In a novel approach to reduce messaging costs in P2P networks, multi-destination multicast is used. Two well known P2P overlays are extended using the Explicit Multi-Unicast (XCAST) protocol. The resulting analysis of this extension provides a strong argument for multiple P2P maintenance algorithms co-existing in a single P2P overlay to provide adaptable performance. A novel multi-tier P2P overlay system is presented, which is tailored for service rich mobile devices and which provides an efficient platform for service discovery

ON MULTIMEDIA CONTENT DELIVERY AND MULTICASTING

Multimedia content now contribute to a huge amount of the Internet traffic due to the popularity and availability of anytime anywhere Internet connection. Unlike the circuit-switched telephone network - in which necessary resources are reserved for communication between two parties at the time the connection is established, a packet-switched network, like the Internet, only guarantees the reachability when the connection between two parties is established. In other words, the end-to-end delay and available bandwidth between two hosts depend on the amount of traffic on the network. The communication paths between the participating hosts are also determined by the routing policies and hence are not under control of the participating hosts. Hence how to improve the performance of delivering multimedia content on the Internet has become an interesting research topic.In this dissertation, we consider the problem of delivering multimedia contents using multicast wherein a group of participants are participating in the same com- munication session. We assume the networks are flexible such that the end hosts can specify the communication paths. A few examples of this type of networks are overlay networks and IPv6 network with source routing support. This problem is addressed from both routing and network traffic perspectives.First, we assume a two-layer approach which includes a well-provisioned service overlay network and the regular Internet. The participants in the multimedia group communication can take the advantage of the service overlay network by connecting to the nodes in the service overlay network through the Internet. We consider two major assignment problems - Server and Client Assignment Problem (SCAP, Client- Server model) and Client Assignment Problem (CAP, Peer-to-Peer model) as well as several variants of these problems. These problems are NP-hard and we have developed polynomial-time heuristic algorithms to assign the participants to appropriate service nodes such that some real-time constraint(s) are satisfied and the number of service nodes involved are minimal. Integer programming (IP) models for solving these problems are also developed for performance evaluation purpose. Empirical results show that the solution quality of the proposed algorithms compares favorably with the optimal ones obtained from the execution of IP models, while keeping the execution times significantly low.We have also considered the Multi-stream Multi-source Multicast Routing Prob- lem ( MMMRP). Given a network and a set of multicast sessions, each with one or more sources and multiple destinations. The goal of MMMRP is to determine mul- tiple multicast tree for these multicast sessions on the given network in such a way that the overall residual bandwidth on the links that are shared among the trees is maximized. We prove that MMMRP is NP-hard and apart from providing an IP formulation, we have also provided a heuristic algorithm MMForests which runs in polynomial-time. We compared and contrasted the performance of MMMRP with known algorithms for the multicast tree packing problem. Our exhaustive empirical evaluations show that our heuristic has a very low execution-time while achieving the optimal residual bandwidth. In addition, our heuristic is very scalable as it is able to produce results for networks with thousands of nodes, unlike the other ones which are based on Steiner tree heuristics

Session Management in Multicast

As a new network technique to efficiently distribute information from a small number of senders to large numbers of receivers, multicast encounters many problems in scalability, membership management, security, etc. These problems hinder the deployment of multicast technology in commercial applications. To overcome these problems, a more general solution for multicast technology is needed. In this paper, after studying current multicast technologies, we summarized the technical requirements for multicast, including data delivery, scalability, security, group management, reliability, and deployment. In order to understand and meet the requirements, we define a life cycle model that most multicast sessions should follow. According to the requirements and the life cycle model, we propose and design a general solution that can control each phase of a session and satisfy most requirements for multicast technology. This general solution has three parts: hierarchical topology auto-configuration algorithm, Session Management Mechanism, and techniques supporting different multicast protocols. To verify the feasibility of our solution and compare its performance with other multicast techniques, we simulate our solution and compare it with PIM-SM and ESM

Scalable adaptive group communication on bi-directional shared prefix trees

Efficient group communication within the Internet has been implemented by multicast. Unfortunately, its global deployment is missing. Nevertheless, emerging and progressively establishing popular applications, like IPTV or large-scale social video chats, require an economical data distribution throughout the Internet. To overcome the limitations of multicast deployment, we introduce and analyze BIDIR-SAM, the rest structured overlay multicast scheme based on bi-directional shared prefix trees. BIDIR-SAM admits predictable costs growing logarithmically with increasing group size. We also present a broadcast approach for DHT-enabled P2P networks. Both schemes are integrated in a standard compliant hybrid group communication architecture, bridging the gap between overlay and underlay as well as between inter- and intra-domain multicast

Modelos, mediciones y tarificación para redes con calidad de servicio

El problema general que se analiza en la tesis es cómo obtener información de la calidad de servicio a lo largo de un camino a los efectos de implementar mecanismos de control de admisión basados no sólo en la información de un enlace sino en la de todo el camino