Exploiting Traffic Balancing and Multicast Efficiency in Distributed Video-on-Demand Architectures

Distributed Video-on-Demand (DVoD) systems are proposed as a solution to the limited streaming capacity and null scalability of centralized systems. In a previous work, we proposed a fully distributed large-scale VoD architecture, called Double P-Tree, which has shown itself to be a good approach to the design of flexible and scalable DVoD systems. In this paper, we present relevant design aspects related to video mapping and traffic balancing in order to improve Double P-Tree architecture performance. Our simulation results demonstrate that these techniques yield a more efficient system and considerably increase its streaming capacity. The results also show the crucial importance of topology connectivity in improving multicasting performance in DVoD systems. Finally, a comparison among several DVoD architectures was performed using simulation, and the results show that the Double P-Tree architecture incorporating mapping and load balancing policies outperforms similar DVoD architectures.This work was supported by the MCyT-Spain under contract TIC 2001-2592 and partially supported by the Generalitat de Catalunya- Grup de Recerca Consolidat 2001SGR-00218

Distributed multimedia systems

A distributed multimedia system (DMS) is an integrated communication, computing, and information system that enables the processing, management, delivery, and presentation of synchronized multimedia information with quality-of-service guarantees. Multimedia information may include discrete media data, such as text, data, and images, and continuous media data, such as video and audio. Such a system enhances human communications by exploiting both visual and aural senses and provides the ultimate flexibility in work and entertainment, allowing one to collaborate with remote participants, view movies on demand, access on-line digital libraries from the desktop, and so forth. In this paper, we present a technical survey of a DMS. We give an overview of distributed multimedia systems, examine the fundamental concept of digital media, identify the applications, and survey the important enabling technologies.published_or_final_versio

Video-on-Demand over Internet: a survey of existing systems and solutions

Video-on-Demand is a service where movies are delivered to distributed users with low delay and free interactivity. The traditional client/server architecture experiences scalability issues to provide video streaming services, so there have been many proposals of systems, mostly based on a peer-to-peer or on a hybrid server/peer-to-peer solution, to solve this issue. This work presents a survey of the currently existing or proposed systems and solutions, based upon a subset of representative systems, and defines selection criteria allowing to classify these systems. These criteria are based on common questions such as, for example, is it video-on-demand or live streaming, is the architecture based on content delivery network, peer-to-peer or both, is the delivery overlay tree-based or mesh-based, is the system push-based or pull-based, single-stream or multi-streams, does it use data coding, and how do the clients choose their peers. Representative systems are briefly described to give a summarized overview of the proposed solutions, and four ones are analyzed in details. Finally, it is attempted to evaluate the most promising solutions for future experiments. Résumé La vidéo à la demande est un service où des films sont fournis à distance aux utilisateurs avec u

Network architecture in a large-scale fully interactive VOD system based on hybrid multicast-unicast streaming.

Chan Kwun-chung.Thesis (M.Phil.)--Chinese University of Hong Kong, 2001.Includes bibliographical references (leaves 71-73).Abstracts in English and Chinese.摘要 --- p.IIABSTRACT --- p.IIIACKNOWLEDGEMENT --- p.VTABLE OF CONTENTS --- p.VILIST OF FIGURES --- p.XLIST OF SYMBOLS --- p.XIIChapter 1. --- INTRODUCTION --- p.1Chapter 1.1 --- Contributions --- p.3Chapter 1.2 --- Organization of the Thesis --- p.4Chapter 1.3 --- Publications --- p.5Chapter 2. --- RELATED WORKS --- p.6Chapter 2.1 --- Previous VOD System --- p.7Chapter 2.1.1 --- Service Model --- p.7Chapter 2.1.1.1 --- Unicast VOD --- p.7Chapter 2.1.1.2 --- Multicast VOD --- p.8Chapter 2.1.2 --- Architecture --- p.9Chapter 2.1.2.1 --- Centralized Architecture --- p.9Chapter 2.1.2.2 --- Distributed Architecture --- p.10Chapter 2.1.3 --- Interactive Function --- p.11Chapter 2.1.3.1 --- Limited Interactive Function --- p.11Chapter 2.1.3.2 --- Unlimited Interactive Function --- p.11Chapter 2.1.4 --- Split and Merge Operation --- p.12Chapter 2.1.4.1 --- SAM Scheme (Split and Merge) --- p.12Chapter 2.1.4.2 --- SRMDRU Scheme (Single Rate Multicast Double Rate Unicast) --- p.14Chapter 2.2 --- Previous Caching Algorithm --- p.15Chapter 2.2.1 --- LFU (Least Frequently Used) --- p.15Chapter 2.2.2 --- LRU (Least Recently Used) --- p.15Chapter 2.2.3 --- Media Stream Caching --- p.15Chapter 3. --- DESIGN OFA NOVEL VOD SYSTEM --- p.17Chapter 3.1 --- System Architecture --- p.18Chapter 3.1.1 --- Multicast Video Server Cluster (MVSC) --- p.19Chapter 3.1.2 --- Unicast Video Server Cluster (UVSC) --- p.20Chapter 3.1.3 --- Multicast Backbone Network (MBN) --- p.20Chapter 3.1.4 --- Local Distribution Network (LDN) --- p.21Chapter 3.1.5 --- Distributed Interactive Server (DIS) --- p.21Chapter 3.1.6 --- Distributed Proxy Server (DPS) --- p.22Chapter 3.1.7 --- Client Station (CS) --- p.22Chapter 3.2 --- Batched Multicast Transmission --- p.24Chapter 3.3 --- Split and Merge Operation --- p.26Chapter 3.4 --- Interactive Function --- p.31Chapter 3.4.1 --- Pause --- p.31Chapter 3.4.2 --- Slow Motion --- p.35Chapter 3.4.3 --- Various Speed Fast Forward / Fast Rewind (FF/REW) --- p.37Chapter 3.4.4 --- Jump Forward/Jump Backward (JF/JB) --- p.42Chapter 3.5 --- Performance Analysis --- p.46Chapter 3.5.1 --- Model --- p.46Chapter 3.5.2 --- System Parameters --- p.49Chapter 3.5.3 --- Results --- p.49Chapter 4. --- DESIGN OF A VIDEO PROXY SYSTEM --- p.57Chapter 4.1 --- Video Proxy System --- p.58Chapter 4.1.1 --- Priority Function --- p.59Chapter 4.1.2 --- Two-Stage Replacement Policy --- p.60Chapter 4.1.3 --- Caching Policy --- p.61Chapter 4.2 --- Performance Evaluation --- p.63Chapter 4.2.1 --- Simulation Environment --- p.63Chapter 4.2.2 --- Performance Metric --- p.64Chapter 4.2.3 --- Results --- p.64Chapter 5. --- CONCLUSION --- p.69BIBLIOGRAPHY --- p.7

System analysis of a Peer-to-Peer Video-on-Demand architecture : Kangaroo

Architectural design and deployment of Peer-to-Peer Video-on-Demand (P2PVoD) systems which support VCR functionalities is attracting the interest of an increasing number of research groups within the scientific community; especially due to the intrinsic characteristics of such systems and the benefits that peers could provide at reducing the server load. This work focuses on the performance analysis of a P2P-VoD system considering user behaviors obtained from real traces together with other synthetic user patterns. The experiments performed show that it is feasible to achieve a performance close to the best possible. Future work will consider monitoring the physical characteristics of the network in order to improve the design of different aspects of a VoD system.El disseny arquitectònic i el desplegament de sistemes de Vídeo sota Demanda "Peer-to-Peer" que soporten funcionalitats VCR està captant l'interès d'un nombre creixent de grups de recerca a la comunitat científica, degut especialment a les característiques intrínsiques dels mencionats sistemes i als beneficis que els peers podrien proporcionar a la reducció de la càrrega en el servidor. Aquest treball tracta l'anàlisi del rendiment d'un sistema P2P-VoD considerant el comportament d'usuaris obtingut amb traçes reals i amb patrons sintètics. Els experiments realitzats mostren que és viable assolir un rendiment proper al cas més óptim. Com treball futur es considerarà la monitorització de les característiques físiques de la xarxa per a poder millorar el disseny dels diferents aspectes que formen un sistema de VoD.El diseño arquitectónico y el despliegue de sistemas de Video bajo Demanda "Peer-to-Peer" que soportan funcionalidades VCR está captando el interés de un número creciente de grupos de investigación dentro de la comunidad científica; especialmente debido a las características intrínsecas de tales sistemas y a los beneficios que los peers podrían proporcionar en la reducción de la carga en el servidor. Este trabajo se enfoca en el análisis de rendimiento de un sistema P2PVoD considerando el comportamiento de usuarios obtenido de trazas reales, junto a otros patrones sintéticos. Los experimentos realizados muestran que es viable lograr un rendimiento cercano al caso más óptimo. El trabajo futuro considerará la monitorización de las características físicas de la red para poder mejorar el diseño de los diferentes aspectos que conforman un sistema de VoD

DIVeR: a dynamic interactive video retrieval protocol for disk array based servers

Video-on-demand (VOD) is a very promising multimedia application of the near future. In order for such a service to be commercially viable, efficient storage and retrieval schemes need to be designed. A scheme for grouping MPEG frames into segments wherein no frames are discarded during fast playback is proposed. In addition, the Dynamic Interactive Video Retrieval (DIVeR) protocol is introduced for scheduling the retrieval of multiple users from disk-array servers.published_or_final_versio

ATOM : a distributed system for video retrieval via ATM networks

The convergence of high speed networks, powerful personal computer processors and improved storage technology has led to the development of video-on-demand services to the desktop that provide interactive controls and deliver Client-selected video information on a Client-specified schedule. This dissertation presents the design of a video-on-demand system for Asynchronous Transfer Mode (ATM) networks, incorporating an optimised topology for the nodes in the system and an architecture for Quality of Service (QoS). The system is called ATOM which stands for Asynchronous Transfer Mode Objects. Real-time video playback over a network consumes large bandwidth and requires strict bounds on delay and error in order to satisfy the visual and auditory needs of the user. Streamed video is a fundamentally different type of traffic to conventional IP (Internet Protocol) data since files are viewed in real-time, not downloaded and then viewed. This streaming data must arrive at the Client decoder when needed or it loses its interactive value. Characteristics of multimedia data are investigated including the use of compression to reduce the excessive bit rates and storage requirements of digital video. The suitability of MPEG-1 for video-on-demand is presented. Having considered the bandwidth, delay and error requirements of real-time video, the next step in designing the system is to evaluate current models of video-on-demand. The distributed nature of four such models is considered, focusing on how Clients discover Servers and locate videos. This evaluation eliminates a centralized approach in which Servers have no logical or physical connection to any other Servers in the network and also introduces the concept of a selection strategy to find alternative Servers when Servers are fully loaded. During this investigation, it becomes clear that another entity (called a Broker) could provide a central repository for Server information. Clients have logical access to all videos on every Server simply by connecting to a Broker. The ATOM Model for distributed video-on-demand is then presented by way of a diagram of the topology showing the interconnection of Servers, Brokers and Clients; a description of each node in the system; a list of the connectivity rules; a description of the protocol; a description of the Server selection strategy and the protocol if a Broker fails. A sample network is provided with an example of video selection and design issues are raised and solved including how nodes discover each other, a justification for using a mesh topology for the Broker connections, how Connection Admission Control (CAC) is achieved, how customer billing is achieved and how information security is maintained. A calculation of the number of Servers and Brokers required to service a particular number of Clients is presented. The advantages of ATOM are described. The underlying distributed connectivity is abstracted away from the Client. Redundant Server/Broker connections are eliminated and the total number of connections in the system are minimized by the rule stating that Clients and Servers may only connect to one Broker at a time. This reduces the total number of Switched Virtual Circuits (SVCs) which are a performance hindrance in ATM. ATOM can be easily scaled by adding more Servers which increases the total system capacity in terms of storage and bandwidth. In order to transport video satisfactorily, a guaranteed end-to-end Quality of Service architecture must be in place. The design methodology for such an architecture is investigated starting with a review of current QoS architectures in the literature which highlights important definitions including a flow, a service contract and flow management. A flow is a single media source which traverses resource modules between Server and Client. The concept of a flow is important because it enables the identification of the areas requiring consideration when designing a QoS architecture. It is shown that ATOM adheres to the principles motivating the design of a QoS architecture, namely the Integration, Separation and Transparency principles. The issue of mapping human requirements to network QoS parameters is investigated and the action of a QoS framework is introduced, including several possible causes of QoS degradation. The design of the ATOM Quality of Service Architecture (AQOSA) is then presented. AQOSA consists of 11 modules which interact to provide end-to-end QoS guarantees for each stream. Several important results arise from the design. It is shown that intelligent choice of stored videos in respect of peak bandwidth can improve overall system capacity. The concept of disk striping over a disk array is introduced and a Data Placement Strategy is designed which eliminates disk hot spots (i.e. Overuse of some disks whilst others lie idle.) A novel parameter (the B-P Ratio) is presented which can be used by the Server to predict future bursts from each video stream. The use of Traffic Shaping to decrease the load on the network from each stream is presented. Having investigated four algorithms for rewind and fast-forward in the literature, a rewind and fast-forward algorithm is presented. The method produces a significant decrease in bandwidth, and the resultant stream is very constant, reducing the chance that the stream will add to network congestion. The C++ classes of the Server, Broker and Client are described emphasizing the interaction between classes. The use of ATOM in the Virtual Private Network and the multimedia teaching laboratory is considered. Conclusions and recommendations for future work are presented. It is concluded that digital video applications require high bandwidth, low error, low delay networks; a video-on-demand system to support large Client volumes must be distributed, not centralized; control and operation (transport) must be separated; the number of ATM Switched Virtual Circuits (SVCs) must be minimized; the increased connections caused by the Broker mesh is justified by the distributed information gain; a Quality of Service solution must address end-to-end issues. It is recommended that a web front-end for Brokers be developed; the system be tested in a wide area A TM network; the Broker protocol be tested by forcing failure of a Broker and that a proprietary file format for disk striping be implemented