P2P based live streaming applications are growing up rapidly. However, when extending them to WLANs, the bandwidth bottleneck and the high rate of packet loss are usually the major stumbling blocks. To overcome this i...
详细信息
P2P based live streaming applications are growing up rapidly. However, when extending them to WLANs, the bandwidth bottleneck and the high rate of packet loss are usually the major stumbling blocks. To overcome this issue, a new wireless multicast agent mechanism (WiMA) based on the IP multicast scheme for buffer management and scheduling is proposed. First of all, a wireless agent selection method is presented to choose an appropriate agent for WiMA. Then this agent gains media data by interacting with wired neighbor peers as a common P2P node, and transmits these data to other wireless peers in the WLAN by means of multicast pushing and multicast patching. A normal wireless peer requests data according to the strategy of "emergent ones first". Experimental results show that the approach proposed can significantly save bandwidth in WLANs with acceptable start delay and satisfied playing continuity.
Virtual machine (VM) based logging-and-replay technology has attracted much attention for system security, fault tolerance, and debugging. However, so far there is not a replay system designed on virtual machine monit...
详细信息
Virtual machine (VM) based logging-and-replay technology has attracted much attention for system security, fault tolerance, and debugging. However, so far there is not a replay system designed on virtual machine monitor Xen. In this paper, XenLR presents the design and implementation of a logging tool for full system replay on Xen. To reduce the design complexity, XenLR is achieved on a lightweight VM mini OS. Our preliminary work dedicates to identify architectural non-deterministic events and record them compactly. XenLR does not modify the guest OS and only need to record the external inputs (keyboard input and time update on mini OS). The log data are saved in the privileged domain¿s file system through transmission channels. The experiments indicate that XenLR results in low time and space overhead. Overhead due to logging is imperceptible for interactive use. The log files grow at 1.4 MByte/day, so it causes litter space consumption for today¿s large capacity disk storage.
This paper describes a method using gridtechnology to improve traffic algorithm efficiency. The method cooperates traffic status estimation algorithm with gridtechnology. It collects and preprocesses massive real-ti...
详细信息
This paper describes a method using gridtechnology to improve traffic algorithm efficiency. The method cooperates traffic status estimation algorithm with gridtechnology. It collects and preprocesses massive real-time data of taxi global positioning system (GPS) as floating car data as well as geographic Information systems (GIS) data of Shanghai urban road network. Then, it adopts gridtechnology to deal with computation for the shortest time path algorithm on traffic status estimation in real time. The results of experiment prove that the gridtechnology can greatly improve the computing efficiency of traffic status estimation model.
Traversing network address translation (NAT) for peer-to-peer (P2P) communication has become a hot topic recently. Compared to UDP, establishing TCP connections for hosts behind different NATs is more complex. Thus, m...
详细信息
Traversing network address translation (NAT) for peer-to-peer (P2P) communication has become a hot topic recently. Compared to UDP, establishing TCP connections for hosts behind different NATs is more complex. Thus, many TCP-based applications do not address TCP traversal through NATs. Some solutions suggest using delegates to relay all communications, or tunneling TCP over UDP. However, they require a big reform to network architecture, or using a nonstandard TCP/IP stack. In this paper, we present a novel idea called TCPBridge. TCPBridge converts TCP traversal to UDP traversal without modifying any binaries of the TCP-based applications. Our design can be integrated with those P2P applications which have not solved TCP traversal problem, and extends them to support direct communications between NAT hosts. It deals with the problem of TCP traversal, so as to improve the usability of applications. We have implemented TCPBridge in several existing P2P systems. Statistics prove that TCPBridge is scalable and robust, and we believe it will benefit many other existing P2P applications.
Monitor substation equipment temperature is one of the most important factors for power systems to ensure safe transmission of electricity. Traditional methods for monitoring the substation temperature shows many disa...
详细信息
The first step towards the information lifecycle management is to differentiate information by values. This paper presents an evaluation model for information value. The idea of the model is from commodity value disci...
详细信息
ISBN:
(纸本)9780769532639
The first step towards the information lifecycle management is to differentiate information by values. This paper presents an evaluation model for information value. The idea of the model is from commodity value discipline in economic area. The output of information value evaluation model is determined by information itself which is like commodity price is determined by use-value in economic area. The output of the model is changed around the real information value and controlled by the relationship between information supply and demand. The output of the model is determined by factors from three aspects that are information itself, information supply, and information demand. When applying the model into traditional information management approaches, such as replication, data migration, and backup, those mechanisms control the output of the model through adjusting the ability of information supply.
There has been significant progress in the development and deployment of peer-to-peer (P2P) live video streaming systems. However, there has been little study on the security aspect in such systems. Our prior experien...
详细信息
ISBN:
(纸本)9781424432134
There has been significant progress in the development and deployment of peer-to-peer (P2P) live video streaming systems. However, there has been little study on the security aspect in such systems. Our prior experiences in Anysee exhibit that existing systems are largely vulnerable to intermediate attacks, in which the content pollution is a common attack that can significantly reduce the content availability, and consequently impair the playback quality. This paper carries out a formal analysis of content pollution and discusses its implications in P2P live video streaming systems. Specifically, we establish a probabilistic model to capture the progress of content pollution. We verify the model using a real implementation based on Anysee system; we evaluate the content pollution effect through extensive simulations. We demonstrate that (1) the number of polluted peers can grow exponentially, similar to random scanning worms. This is vital that with 1% polluters, the overall system can be compromised within minutes; (2) the effective bandwidth utilization can be sharply decreased due to the transmission of polluted packets; (3) Augmenting the number of polluters does not imply a faster progress of content pollution, in which the most influential factors are the peer degree and access bandwidth. We further examine several techniques and demonstrate that a hash-based signature scheme can be effective against the content pollution, in particular when being used during the initial phase.
Peers in multiple P2P applications execute overlapped operations with different implementation, like neighbour management, resource publish/lookup, delay investigation, which leads to poor interoperability and unneces...
详细信息
Peers in multiple P2P applications execute overlapped operations with different implementation, like neighbour management, resource publish/lookup, delay investigation, which leads to poor interoperability and unnecessary network load. Peers contribute their resources only when they stay in same application. We propose a P2P middleware, called Ripple, to accomplish common functions in a layered architecture. Ripple manages all peers running various applications in a uniform substrate overlay network. The substrate overlay is designed with a hybrid topology. This hybrid topology does not aim at only a particular type of applications, but also enables the flexibility for various applications. Our work is an attempt to address common needs of P2P applications, which may simplify the development and improve the performance of P2P networks, as well as mitigate the sampling stress to physical networks.
As the world of gridcomputing is continuously growing, scalability and complexity of gridsystems are in an increasing rate. Moreover, gridsystems are dynamic and subject to various changes. Management of such chang...
详细信息
As the world of gridcomputing is continuously growing, scalability and complexity of gridsystems are in an increasing rate. Moreover, gridsystems are dynamic and subject to various changes. Management of such changes is a challenging issue facing grid communities. Namely, how to efficiently maintain gridsystem to adopt the environment modification, to meet the user demands and to manage the dynamic changes has become a big challenge. Manual- or script based maintenance approaches are tedious, time consuming and complex, in addition to being highly prone to errors. Therefore, state-of-the-art maintenance models are designed to support transparent runtime maintenance, fast and comprehensive respond to environmental changes and requirements, consequently, improve the availability and efficiency of the gridsystem. This paper focuses on investigating maintenance models and their common characteristics for grid. To this end, this paper surveys several representative grid maintenance model systems developed by various projects worldwide. The contributions of this paper are (i) discussing the motivations of maintenance for gridsystem, (ii) discussing the issues and the challenges in building maintenance mechanisms for gridsystem, (iii) reviewing maintenance models and compare their efficiencies for gridsystem, and (iv) discussing possible new directions.
Free riding is a great challenge to the development and maintenance of Peer-to-Peer(P2P)networks.A file migration and workload balancing based approach (FMWBBA)to discourage free riding is proposed in this *** heart o...
详细信息
Free riding is a great challenge to the development and maintenance of Peer-to-Peer(P2P)networks.A file migration and workload balancing based approach (FMWBBA)to discourage free riding is proposed in this *** heart of our mechanism is to migrate some shared files from the overloaded peers to the neighboring free riders automatically and transparently,which enforces free riders to offer services when altruistic peers are heavily *** migration is a key issue in our approach,and some related strategies are discussed.A simulation is designed to verify this approach,and the results show that it can not only alleviate free riding,but also improve the Quality of Service(QoS)and robustness of P2P networks efficiently.
暂无评论