Networked Virtual Environments Research Articles

A two-dimensional architecture for end-to-end resource management in virtual network environments

In recent years, various network virtualization techniques have been proposed for flexibly supporting heterogeneous services over virtual network platforms. However, systematic views on how virtual network resources (VNRs) can be practically managed in such open environments has been missing till now. To fill the gap, we present in this article a two-dimensional architecture for end-to-end VNR management from distinct viewpoints of service providers and network providers. The horizontal dimension of VNR management allows SPs to bind VNRs rented from heterogeneous NPs to form unified end-to-end service delivery platforms. The vertical dimension of VNR management enables NPs to perform cost-efficient allocation of VNRs to requesting SPs, but without necessarily forcing themselves to collaborate with each other. Such a VNR management architecture will complement existing network virtualization platforms in accelerating the realization of virtual resource sharing in the future Internet business marketplaces.

Inter-destination multimedia synchronization: schemes, use cases and standardization

Traditionally, the media consumption model has been a passive and isolated activity. However, the advent of media streaming technologies, interactive social applications, and synchronous communications, as well as the convergence between these three developments, point to an evolution towards dynamic shared media experiences. In this new model, geographically distributed groups of consumers, independently of their location and the nature of their end-devices, can be immersed in a common virtual networked environment in which they can share multimedia services, interact and collaborate in real-time within the context of simultaneous media content consumption. In most of these multimedia services and applications, apart from the well-known intra and inter-stream synchronization techniques that are important inside the consumers’ playout devices, also the synchronization of the playout processes between several distributed receivers, known as multipoint, group or Inter-destination multimedia synchronization (IDMS), becomes essential. Due to the increasing popularity of social networking, this type of multimedia synchronization has gained in popularity in recent years. Although Social TV is perhaps the most prominent use case in which IDMS is useful, in this paper we present up to 19 use cases for IDMS, each one having its own synchronization requirements. Different approaches used in the (recent) past by researchers to achieve IDMS are described and compared. As further proof of the significance of IDMS nowadays, relevant organizations’(such as ETSI TISPAN and IETF AVTCORE Group) efforts on IDMS standardization (in which authors have been and are participating actively), defining architectures and protocols, are summarized.

An information-based dynamic extrapolation model for networked virtual environments

Various Information Management techniques have been developed to help maintain a consistent shared virtual world in a Networked Virtual Environment. However, such techniques have to be carefully adapted to the application state dynamics and the underlying network. This work presents a novel framework that minimizes inconsistency by optimizing bandwidth usage to deliver useful information. This framework measures the state evolution using an information model and dynamically switches extrapolation models and the packet rate to make the most information-efficient usage of the available bandwidth. The results shown demonstrate that this approach can help optimize consistency under constrained and time-varying network conditions.

Mobility and Network Management in Virtualized Networks

Management, be it multi-access, resource, mobility or network management, is a key aspect in the design, deployment and operation of current and future networks. The challenges that mobile network management faces today are increasingly associated with the multiplicity of operating environments. For instance, heterogeneous resource sharing, dealing with a larger variety of user profiles, and operating diverse network infrastructures have become commonplace. In this context, it is natural that we witness proliferation and adoption of virtualization techniques in different areas of information and communication technologies (ICT), which then introduce their own management challenges. Although certain virtualization techniques are already embraced in telecommunication networks, such as network sharing, the full potential that can be achieved from a completely virtualized network environment is yet to be realized. In practice, we are not able to fully control these environments. Proponents of network virtualization point to the dramatically increased flexibility in running networks, enabling multiple networks to operate simultaneously over the same infrastructure, while supporting different technologies, protocols, topologies, and quality of service (QoS) and experience (QoE) requirements. All these are not possible with today’s technology. Although virtualization has been studied extensively in other domains, its application to mobile networks is an emergent topic of active research and its impact on resource, mobility, and network management, as well as the related security and autonomicity challenges are open for investigation. What is certain though is that the interest in mobile networks and virtualization is geared to increase. Before we go ahead with the core topic of this special issue, let us stand back for a moment and consider how mobile infrastructure networks have evolved. Traditionally, mobile operators deployed their own, dedicated, access network-specific infrastructure in order to offer different network services to their subscribers. This is not always the case anymore. As we move towards the widespread deployment of mobile broadband based on the fourth generation (4G) of cellular networks, and in parallel with the continuous expansion of previous generation networks, we see that key stakeholders (from operators to regulators) consider changing their modus operandi with respect to network infrastructure build out. We expect that increased infrastructure sharing will be very common in the mid-term. This should not be surprising. The way we understand and interact with communication commodities is continuously evolving. What is new, though, is that the pace of changes in this line of evolution has dramatically accelerated during the last decade, leading to a somewhat hard(er) to forecast path in terms of technology evolution. Although this spans throughout ICT technologies, protocols and infrastructures, wireless and mobile networks are perhaps the most representative example of such an evolution. K. Pentikousis (*) Huawei Technologies, Carnotstrasse 4, 10587 Berlin, Germany e-mail: k.pentikousis@huawei.com

Full Body Acting Rehearsal in a Networked Virtual Environment — A Case Study

In order to rehearse for a play or a scene from a movie, it is generally required that the actors are physically present at the same time in the same place. In this paper we present an example and experience of a full body motion shared virtual environment (SVE) for rehearsal. The system allows actors and directors to meet in an SVE in order to rehearse scenes for a play or a movie, that is, to perform some dialogue and blocking (positions, movements, and displacements of actors in the scene) rehearsal through a full body interactive virtual reality (VR) system. The system combines immersive VR rendering techniques as well as network capabilities together with full body tracking. Two actors and a director rehearsed from separate locations. One actor and the director were in London (located in separate rooms) while the second actor was in Barcelona. The Barcelona actor used a wide field-of-view head-tracked head-mounted display, and wore a body suit for real-time motion capture and display. The London actor was in a Cave system, with head and partial body tracking. Each actor was presented to the other as an avatar in the shared virtual environment, and the director could see the whole scenario on a desktop display, and intervene by voice commands. A video stream in a window displayed in the virtual environment also represented the director. The London participant was a professional actor, who afterward commented on the utility of the system for acting rehearsal. It was concluded that full body tracking and corresponding real-time display of all the actors' movements would be a critical requirement, and that blocking was possible down to the level of detail of gestures. Details of the implementation, actors, and director experiences are provided.

A Traffic Classification Agent for Virtual Networks Based on QoS Classes

Internet growth drives the emergence and usage of new applications, which have specific requirements for Quality of Service (QoS). Thus, differentiation of packets which belong to certain QoS classes becomes a crucial factor to ensure the desirable quality for the applications. Within this context, this paper proposes an agent for real-time traffic classification based on QoS classes for virtual network environments, which aims at forwarding the flow to the adequate virtual network according to the QoS class. The study was made using the Mininet emulator and the Openflow Protocol. And the study showed that the agent using the Naive Bayes method performs the more suitable classification in real time.

Quantitative analysis of visibility determinations for networked virtual environments

The Area-Of-Interest (AOI) model is a simple and popular technique used in many applications to determine the region which needs to be considered and processed for each entity (e.g., user). One example application is object visibility determination around user-representing avatars in virtual environments or networked games. There exist a number of variations of the AOI model and in our prior work we have demonstrated how object-oriented visibility determination is more suitable for networked virtual environments than conventional user-oriented visibility determination. Here we extend our work to study a unified and comprehensive analytical model that reveals fundamental properties about the different visibility determination techniques under a variety of virtual environment settings. We also present what the best operational scenarios are for each different approach. Although our discussion and analytical results are focused on the visibility domain, the arguments and conclusions can be extended to various applications or services where spatial attributes are required.

Dynamically Adaptive Bandwidth Allocation In Network Virtualization Environment

Dynamically Adaptive Bandwidth Allocation In Network Virtualization Environment

A Resource Finding Mechanism for Network Virtualization Environment

There are large numbers of infrastructure resources in network virtualization environment (NVE), how to quickly and accurately find the resources that virtual network required is a challenging problem. Pointing to this problem, a resource finding mechanism for network virtualization environment (NVERFM) is proposed. NVERFM is mainly comprised of three modules, virtual resources publishing module (VRPM), virtual resources clustering framework (VRCF), and virtual resources finding module (VRFM). VRPM is responsible for publishing the infrastructure resources to VRCF; and the published information contains functional and non-functional attributes. VRCF is responsible for classifying the published information into different clustering according to the attributes from high priority to low priority. VRFM mainly completes resource finding based on resource similarity principle. Finding the resource clustering that meet the user’s requirements; and then combinatorial auction mechanism is used to help users choose the optimal infrastructure resource. Finally, experiments are used to validate NVERFM, and the results show that NVERFM can not only help users find the optimal resource, but also improve the efficiency.

Resource Discovery and Allocation in Network Virtualization

Network virtualization is considered an important potential solution to the gradual ossification of the Internet. In a network virtualization environment, a set of virtual networks share the resources of a common physical network although each virtual network is isolated from others. Benefits include increased flexibility, diversity, security and manageability. Resource discovery and allocation are fundamental steps in the process of creating new virtual networks. This paper surveys previous work on, and the present status of, resource discovery and allocation in network virtualization. We also describe challenges and suggest future directions for this area of research.

A Collaborative Molecular Modeling Environment Using a Virtual Tunneling Service

Collaborative researches of three-dimensional molecular modeling can be limited by different time zones and locations. A networked virtual environment can be utilized to overcome the problem caused by the temporal and spatial differences. However, traditional approaches did not sufficiently consider integration of different computing environments, which were characterized by types of applications, roles of users, and so on. We propose a collaborative molecular modeling environment to integrate different molecule modeling systems using a virtual tunneling service. We integrated Co-Coot, which is a collaborative crystallographic object-oriented toolkit, with VRMMS, which is a virtual reality molecular modeling system, through a collaborative tunneling system. The proposed system showed reliable quantitative and qualitative results through pilot experiments.

分散仮想環境における香りの動的出力タイミング制御のユーザ体感品質評価

In this paper, we propose dynamic output timing control of fragrance in a networked virtual environment to improve the quality of experience (QoE). The control changes the output timing of fragrance dynamically in accordance with the movement speed and direction of a fragrance source. We implement the control in a remote ikebana (Japanese flower arrangement) system with olfaction and haptic sense and investigate the effect of the control by QoE assessment. As a result, we demonstrate that the mean opinion score (MOS) when the control is used is high and does not depend much on the movement speed and direction of the flower, which is the fragrance source.

Adaptive scheme based on status feedback for virtual network mapping

Network virtualization is considered as a powerful way to deploy different network architectures and protocols over a shared physical infrastructure. Virtual network (VN) embedding plays an important role in the network virtualization environment. Virtual network embedding is mainly about mapping virtual nodes and virtual links onto the physical network resources efficiently. However, load balancing of substrate network has not received much consideration. This paper proposes an adaptive virtual network mapping algorithm based on status feedback. The main contribution is to embed the virtual network requests according to the current load distribution of substrate network. This adaptive algorithm differentiates the residual bandwidth of substrate links and takes full advantage of the multi-path to improve the load balancing of the substrate network. Simulation experiments show that the proposed algorithm improves the load distribution of substrate network distinctly while reducing the average substrate link stress significantly.

Multi Agent System based TCP for Wireless Networks

to the rapid evolution of networking and electronic capabilities, the use of wireless devices is becoming ubiquitous. Most of the wireless networks have fixed infrastructure and requires higher data rates. Due to high data rate in wireless networks the Transmission Control Protocol (TCP) performance has a broad and significant impact on data applications, and is essential towards massive deployment of service-providing agents and their widespread social acceptance. Wireless link losses result in poor TCP throughput since losses are professed as congestion by TCP. In order to increase the throughput, a Multi agent System (MAS) named Reusable Environment for Task-Structured Intelligent Networked Agents (RETSINA) has been introduced. This agent has the capability to reduce the impact of losses on TCP throughput and latency. In this work, we considered a video game application in which a networked virtual environment with high fidelity sound and video is created. Moreover, to efficiently use the video game application in a wireless environment, an Unreal Tournament Semi-Automated Force (UTSAF) multi agent has been proposed. UTSAF is a middleware written to take advantage of the power of gaming application systems by allowing them to participate in distributed simulations. The personal agent communicates wirelessly, in order to find the most appropriate option to serve the user. In addition, we comprehensively evaluated the performance of TCP with and without these multi agent platforms as technology choice and investigated its efficiency in a number of cases. We find that the simulations with the multi agent can reach the TCP throughput by as much as 95 % and the latency get reduced by 1-2 % as the simulation time steps in for every 100 seconds.

전자상거래 시스템의 트래픽량 예측에 관한 연구

네트워크 기반의 적절한 컴퓨팅은 네트워크 대역폭의 가용성에 의존한다. 백본 네트워크 용량과 액세스 네트워크 상에 심각한 버틀넥이 발생하여 ISP 사업자와 고객 간의 갭이 발생된다면 그만큼 ISP 사업자는 사업에 불이익을 초래할 수 있다. 이러한 상황이 발생되기 이전 ISP 사업자가 트래픽량 예측과 종단간 오버로드가 높은 링크 구간을 감지할 수 있다면 ISP 사업자와 고객 간의 갭은 그만큼 줄어 들 수 있을 것으로 판단된다. 따라서 본 논문은 트래픽량 예측과 종단간 오버로드가 높은 링크 구간을 감지 가능한 소프트웨어로 ACE, ADM, Flow Analysis를 소개한다. 이들 툴을 이용하여 전자상거래의 연속적인 트랜잭션을 실망에서 측정한 후 측정된 네트워크 데이터를 가상 망 환경에 임포트하고 백그라운드 트래픽을 생성한다. 이와 같은 가상 망 환경을 토대로 점차적인 사용자 수 증가에 따른 트래픽량 예측과 링크 로드가 높은 구간을 시뮬레이션 결과로 알 수 있었다. The applicability of network-based computing depends on the availability of the underlying network bandwidth. Such a growing gap between the capacity of the backbone network and the end users' needs results in a serious bottleneck of the access network in between. As a result, ISP incurs disadvantages in their business. If this situation is known to ISP in advance, or if ISP is able to predict traffic volume end-to-end link high-load zone, ISP and end users would be able to decrease the gap for ISP service quality. In this paper, simulation tools, such as ACE, ADM, and Flow Analysis, were used to be able to perceive traffic volume prediction and end-to-end link high-load zone. In using these simulation tools, we were able to estimate sequential transaction in real-network for e-Commerce. We also imported virtual network environment estimated network data, and create background traffic. In a virtual network environment like this, we were able to find out simulation results for traffic volume prediction and end-to-end link high-load zone according to the increase in the number of users based on virtual network environment.

Traffic Anomaly Analysis and Characteristics on a Virtualized Network Testbed

Network testbeds have been used for network measurement and experiments. In such testbeds, resources, such as CPU, memory, and I/O interfaces, are shared and virtualized to maximize node utility for many users. A few studies have investigated the impact of virtualization on precise network measurement and understood Internet traffic characteristics on virtualized testbeds. Although scheduling latency and heavy loads are reportedly affected in precise network measurement, no clear conditions or criteria have been established. Moreover, empirical-statistical criteria and methods that pick out anomalous cases for precise network experiments are required on userland because virtualization technology used in the provided testbeds is hardly replaceable. In this paper, we show that ‘oversize packet spacing’, which can be caused by CPU scheduling latency, is a major cause of throughput instability on a virtualized network testbed even when no significant changes occur in well-known network metrics. These are unusual anomalies on virtualized network environment. Empirical-statistical analysis results accord with results at previous work. If network throughput is decreased by the anomalies, we should carefully review measurement results. Our empirical approach enables anomalous cases to be identified. We present CPU availability as an important criterion for estimating the anomalies.

A P2P-based Management Method for Dynamic AOI

Networked virtual environments (NVEs) are distributed systems where geographically dispersed users interact with each other in virtual worlds by exchanging network messages. Massively Multiplayer Online Game (MMOG) is one of diverse applications where more than hundreds of users enjoy experiencing virtual worlds. A limited area called area of interest (AOI) in MMOG is reduced the load caused by message exchange between users. Voronoi-based Overlay Network (VON) is proposed to reduce the bandwidth consumption in P2P environments and Vorocast also is made using message forwarding in VON. We propose a dynamic AOI management method that solves problems such as a consistency and latency due to forwarding position updates to neighbor nodes from the message originator in forwarding scheme. Our scheme provides the consistency and reduces latency by combining direct connection scheme and Vorocast scheme compared to existing schemes. The communication between a user and users existing in center circle within AOI of the user is directly connected and the communication between the user and users existing outside the center area within AOI is using Vorocast scheme. The proposed model is evaluated through simulations.

Real and OPNET modeling and analysis of an enterprise network and its security structures

Abstract In this research study, first, a prototype network design as real modeling and using the OPNET software as virtual modeling of a typical enterprise network are constructed and analyzed. On these real and virtual network models, the affects of Firewall and VPN (Virtual Private Network) on network performance are studied. Then a more complex and realistic model than the first simple OPNET model is designed, and on this second model similar analysis work is performed. In this study, another research topic is to investigate application areas and uses of OPNET in communication networks education. What we have done different than the previous research studies and projects in our study is constructing both a real enterprise network prototype and virtual OPNET simulation model, and comparing network models and network analysis results. The affects of Firewall and VPN on these models are studied in both real network devices and virtual OPNET environments. Additionally, practical use of both developed real and virtual models in university education is also taken into consideration.

Combining Contact Models With Perceptual Data Reduction for Efficient Haptic Data Communication in Networked VEs

In cooperative networked virtual environments, haptic rendering enables joint haptic interaction with virtual objects and, thus, shared touch experiences among multiple users. In case of an underlying packet-based communication network (e.g., the Internet), minimizing the end-to-end delay, with the goal of preventing instability of the involved control loops, results in high packet rates. Previously proposed perceptual data reduction approaches address this challenge and satisfy the strict delay constraints. However, significantly increased packet rates still occur during contact events. We present a novel event-based coding scheme based on a distributed haptic-rendering framework that integrates model-based distributed haptic rendering with perceptual data reduction. We also present a comprehensive haptic contact model for signals with multiple degrees of freedom. Furthermore, we show that the integration of event-triggered force transient models from event-based haptics into our local contact model is instrumental for generating convincing haptic feedback. Psychophysical experiments reveal that the approach presented herein allows us to push the data reduction performance beyond what is normally achievable by perceptual data reduction schemes alone while significantly improving the quality of haptic contact feedback.

P2Life: An Infrastructure for Networked Virtual Marketplace Environments

Networked Virtual Environments (NVEs) which are based on Peer-to-Peer technology aim to provide large-scale virtual worlds without bottlenecks coming from centralized instances. Current approaches focus on massively multiplayer online games, but little work has been done on designing NVEs that enable trading goods and services for real money. In this article, the specific threats on such networked virtual marketplace environments (NVMEs) are discussed. Consecutively, requirements for the underlying network structure are derived to avoid them. Finally, an efficient lookup protocol for persistent objects in NVMEs is presented, which can be set on top of distributed hashtables and allows scalable virtual environments of unlimited size.