On the effectiveness of an optimization method for the traffic of TCP-based multiplayer online games

This paper studies the feasibility of using an optimization method, based on multiplexing and header compression, for the traffic of Massively Multiplayer Online Role Playing Games (MMORPGs) using TCP at the Transport Layer. Different scenarios where a number of flows share a common network path are identified. The adaptation of the multiplexing method is explained, and a formula of the savings is devised. The header compression ratio is obtained using real traces of a popular game and a statistical model of its traffic is used to obtain the bandwidth saving as a function of the number of players and the multiplexing period. The obtained savings can be up to 60 % for IPv4 and 70 % for IPv6. A Mean Opinion Score model from the literature is employed to calculate the limits of the multiplexing period that can be used without harming the user experience. The interactions between multiplexed and non-multiplexed flows, sharing a bottleneck with different kinds of background traffic, are studied through simulations. As a result of the tests, some limits for the multiplexing period are recommended: the unfairness between players can be low if the value of the multiplexing period is kept under 10 or 20 ms. TCP background flows using SACK (Selective Acknowledgment) and Reno yield better results, in terms of fairness, than Tahoe and New Reno. When UDP is used for background traffic, high values of the multiplexing period may stress the unfairness between flows if network congestion is severe

Analyzing the effect of tcp and server population on massively multiplayer games

Many Massively Multiplayer Online Role-Playing Games (MMORPGs) use TCP flows for communication between the server and the game clients. The utilization of TCP, which was not initially designed for (soft) real-time services, has many implications for the competing traffic flows. In this paper we present a series of studies which explore the competition between MMORPG and other traffic flows. For that aim, we first extend a source-based traffic model, based on player’s activities during the day, to also incorporate the impact of the number of players sharing a server (server population) on network traffic. Based on real traffic traces, we statistically model the influence of the variation of the server’s player population on the network traffic, depending on the action categories (i.e., types of in-game player behaviour). Using the developed traffic model we prove that while server population only modifies specific action categories, this effect is significant enough to be observed on the overall traffic. We find that TCP Vegas is a good option for competing flows in order not to throttle the MMORPG flows and that TCP SACK is more respectful with game flows than other TCP variants, namely, Tahoe, Reno, and New Reno. Other tests show that MMORPG flows do not significantly reduce their sending window size when competing against UDP flows. Additionally, we study the effect of RTT unfairness between MMORPG flows, showing that it is less important than in the case of network-limited TCP flows

Managing Network Delay for Browser Multiplayer Games

Latency is one of the key performance elements affecting the quality of experience (QoE) in computer games. Latency in the context of games can be defined as the time between the user input and the result on the screen. In order for the QoE to be satisfactory the game needs to be able to react fast enough to player input. In networked multiplayer games, latency is composed of network delay and local delays. Some major sources of network delay are queuing delay and head-of-line (HOL) blocking delay. Network delay in the Internet can be even in the order of seconds. In this thesis we discuss what feasible networking solutions exist for browser multiplayer games. We conduct a literature study to analyze the Differentiated Services architecture, some salient Active Queue Management (AQM) algorithms (RED, PIE, CoDel and FQ-CoDel), the Explicit Congestion Notification (ECN) concept and network protocols for web browser (WebSocket, QUIC and WebRTC). RED, PIE and CoDel as single-queue implementations would be sub-optimal for providing low latency to game traffic. FQ-CoDel is a multi-queue AQM and provides flow separation that is able to prevent queue-building bulk transfers from notably hampering latency-sensitive flows. WebRTC Data-Channel seems promising for games since it can be used for sending arbitrary application data and it can avoid HOL blocking. None of the network protocols, however, provide completely satisfactory support for the transport needs of multiplayer games: WebRTC is not designed for client-server connections, QUIC is not designed for traffic patterns typical for multiplayer games and WebSocket would require parallel connections to mitigate the effects of HOL blocking

Distributed game

Dissertação de mestrado em Engenharia InformáticaThe demand for online games has risen over the years, expanding multiplayer support for new and different game genres. Among them are Massively Multiplayer Online games, one of the most popular and successful game types in the industry. Nowadays, this industry is thriving, evolving alongside technological advancements and producing billions in revenue, making it an economic importance. However, as the complexity of these games grows, so do the challenges they face when constructing them. This dissertation aims to implement a distributed game, through a proof of concept or an existing game, using a distributed architecture to acquire knowledge in the construction of such complex systems and the effort involved in dealing with consistency, maintaining communication infrastructure, and managing data in a distributed way. It is also intended that this project implements multiple mechanisms capable of autonomously helping manage and maintain the correct state of the system. To evaluate the proposed solution, a detailed analysis is carried out with performance benchmark analysis, stress testing, followed by an examination of its security, scalability, and distribution’s resilience. Overall, the present research work allowed for a greater understanding of the technologies and approaches used in constructing a gaming system, establishing a new set of development opportunities to be further investi gated upon the constructed solution.A procura por jogos online aumentou ao longo dos anos, expandindo o suporte multiplayer para novos e diferentes géneros. Entre estes estão os jogos Massively Multiplayer Online, um dos tipos de jogos mais populares e bem-sucedidos na indústria. Atualmente, esta indústria está a prosperar, evoluindo com os avanços tecnológicos e gerando milhares de milhões em receita, tornando-se uma importância económica. Porém, à medida que a complexidade destes jogos aumenta, também aumenta os problemas encontrados durante a sua construção. Esta dissertação tem como objetivo implementar um jogo distribuído, através de uma prova de conceito ou um jogo existente, usando uma arquitetura distribuída a fim de adquirir conhecimento na construção destes sistemas complexos e o esforço envolvido em lidar com consistência, manter a infraestrutura de comunicação e gerir dados de maneira distribuída. Para isto, é pretendido que este projeto também implemente vários mecanismos capazes de, forma autônoma, ajudar a gerir e manter o correto estado do sistema. Para avaliar o solução proposta, uma análise detalhada é realizada sobre o desempenho, segurança, escalabilidade e resiliência da distribuição do sistema. De forma geral, o presente trabalho de pesquisa permitiu uma maior compreensão das tecnologias e abordagens utilizadas na construção de um sistema de jogos, estabelecendo um novo conjunto de oportunidades de desenvolvimento a serem investigadas sobre a solução construída

Architecting Scalability for Massively Multiplayer Online Gaming Experiences

With this article we want to identify the main scalability issues for the development of Massive Multi-Player Online Games. There is no generic architecture to achieve scalability for every problem. We must understand the nature of the problem in order to reach system scalability. Massive Multi-Player Online Games (MMOG) are conceived with the objective of massive use by a potentially geographically dispersed population. In their design we are faced with scalability challenges which are specific to the interactive modalities and the socio-technical scenarios we intend to enable [Fitch 2001]. The emergence of the Internet made possible the development of interactive distributed systems that can be accessed by thousands of users in virtually any part of the world. The scalability issues introduced by such a massive use must be considered in the system design. By scalability we mean the system fit capacity according to his loading charge, for example, accommodates increasing interaction volume, without significant degradation of quality service. It is commonly known that scalability can’t be secured if we only pay attention to some system parts. To achieve scalability in any kind of distributed system we must design all the components to achieve this goal. For example, a system that has high scalability in the simulation and low communication scalability may result in a poor scalable system, globally. To see the scalability problems in a MMOG we must understand the system dynamics and structure and what’s bound for. Looking at the existent types of MMOG – massive multi-player online role playing games, virtual environments, massive multiplayer real time strategy, massive multiplayer online first-person shooter – we can try to generalize some features that allow us to analyze their scalability requisites. Normally, in this kind of games the action takes place in a virtual 3D environment, where thousands of players interact by controlling avatars, allowing real-time interaction between users in simulated virtual worlds. The action environment can be persistent in order to maintain the notion of space and time continuity [wikipedia 2004]. From an analysis of the characteristics of MMOG systems and their usage we can start to identify four main scalability issues: a) simulation capacity that allows for thousands of players to be online in the same virtual world; b) data storage capacity of all the information that is used to represent the virtual worlds and one efficient distribution method for guaranteeing availability when needed; c) reliable and efficient communications for experience coordination and smooth interaction; d) architectural integration enabling system expansibility through new computational, communication and storage resources. Next we will briefly discuss these issues. The simulation component role in MMOG is to process the events that are generated through the player’s interaction or by sub-systems that generate automatic environmental activities (e.g., atmospheric, AI bots). Besides the high event volume that must be processed, the simulation activity has other challenge: the size of the virtual universe data model. Virtual universe action area can have the size of a planet or even a galaxy, which becomes very complex to handle [Rosedale 2003]. As previously referred, the MMOG environments are commonly 3D and very dynamic, being impossible for the clients to keep the virtual world state. So, when a player enters the virtual world must be given to him all the information necessary to animate that world. This information has two different types: data model that represents abstractly the virtual world; and the necessary multimedia elements needed to visual and sonorous animation. Nature and volume size of multimedia information become the main problem of the distribution system [Yu-Shen 1997]. Communication scalability is one of the essential issues in simulated real-time games through Internet. Scalability must be understood not only by the capacity to support communication between a high numbers of players, but also, as the capacity to maintain a communication performance level that doesn’t put at risk the game experience quality. This fact in the MMOG systems is paradigmatic, since there are possible thousand of players interacting with the world objects and moving in the same space. Objects state and players activity must be informed to all players in order to maintain the game integrity/consistency [Smed 2001]. Structural scalability is important to increase the system live span. In order to achieve this requisite the system structure must be designed to enable the addition of new resources. Architectural scalability, through the specification of clear system components that interact in a clear dynamics, through defined protocols, is a pre-requisite for system repairing, actualization and evolution; and must also have the capacity to integrate significantly contribute to the later incorporation of new technologies and devices. At first glance, we would think that to achieve scalability in MMOG implementations we would simply have to work on an architectural design to satisfy all the requisites that have been presented. But that would not be enough. System scalability also emerges from the balance and harmony of the system components. When we are trying to satisfy some requisite, the ideal solution may be in conflict with some other requisite. For example, the best solution for the distribution of static content (such as 3D models, textures and sounds) can jeopardize communication scalability for more immediate real-time events, as their compete for the available bandwidth. The best solution may not be the optimal one for any system component, but the best overall solution for the integrated system, that guarantees an adequate level of quality to the interactive experience. In order to achieve such a balance we have to consider an adequate partitioning of responsibilities for the components and the internal and the external dynamics that are originated

Imagining the Internet in Future

In this paper, we imagining the Future Internet (ICN and NDN architecture). We discuss examples of edge computing and IoT. We chose these areas because they are very important topics in today research. We also discuss provider mobility, P2P architectures, sync, and simulation tools. We discuss open questions for research

A survey on interactive games over mobile networks

open4noThe mobile revolution has brought us the possibility to enjoy our favorite applications anywhere and anytime. In this context, interactive games over mobile networks embody a fascinating case study both for their commercial success and for their technical challenges, thus, sparking interest and development. The current state of the art of interactive games over mobile networks is captured in this article. We discuss main requirements and analyze possible combinations of existing solutions to provide better support for highly interactive game sessions with mobile players.This work has been partially supported by the UniPD Web Squared and MIUR/PRIN ALTER_NET projects.openGerla, M.; Maggiorini, D.; Palazzi, C.E.; Bujari, A.Gerla, M.; Maggiorini, D.; Palazzi, C.E.; Bujari, A

Clouds + Games: A multifaceted approach

The computer game landscape is changing: people play games on multiple computing devices with heterogeneous form-factors, capability, and connectivity. Providing high playability on such devices concurrently is difficult. To enhance the gaming experience, designers could leverage abundant and elastic cloud resources, but current cloud platforms aren't optimized for highly interactive games. Existing studies focus on streaming-based cloud gaming, which is a special case for the more general cloud game architecture. The authors explain how to integrate techniques from the cloud and game research communities into a complete architecture for enhanced online gaming quality. They examine several open issues that appear only when clouds and games are put together. © 2014 IEEE