Capacity-aware multicast algorithms on heterogeneous overlay networks

The global deployment of IP multicast has been slow due to the difficulties related to heterogeneity, scalability, manageability, and lack of a robust interdomain multicast routing protocol. Application-level multicast becomes a promising alternative. Many overlay multicast systems have been proposed in recent years. However, they are insufficient in supporting applications that require any-source multicast with varied host capacities and dynamic membership. In this paper, we propose two capacity-aware multicast systems that focus on host heterogeneity, any source multicast, dynamic membership, and scalability. We extend Chord and Koorde to be capacity-aware. We then embed implicit degree-varying multicast trees on top of the overlay network and develop multicast routines that automatically follow the trees to disseminate multicast messages. The implicit trees are well balanced with the workload evenly spread across the network. We rigorously analyze the expected performance of multisource capacity-aware multicasting, which was not thoroughly addressed in any previous work. We also perform extensive simulations to evaluate the proposed multicast systems.     

多源异构环境下数据同步复制技术的研究

针对多源异构环境下数据的特点,提出一种数据同步复制新方案。该方案解决了多源异构环境下数据库的访问,数据的获取与复制,动态数据源的处理以及同步过程中数据冲突与同步的实时性等问题。最后将所提出的方案应用于某省高速公路车辆监控系统中,达到了实际应用要求,表明了该方案的正确性与有效性。     

Mutual anonymous overlay multicast

Multicast services are demanded by a variety of applications. Many applications require anonymity during their communication. However, there has been very little work on anonymous multicasting and such services are not available yet. Due to the fundamental differences between multicast and unicast, the solutions proposed for anonymity in unicast communications cannot be directly applied to multicast applications. In this paper we define the anonymous multicast system, and propose a mutual anonymous multicast (MAM) protocol including the design of a unicast mutual anonymity protocol and construction and optimization of an anonymous multicast tree. MAM is self-organizing and completely distributed. We define the attack model in an anonymous multicast system and analyze the anonymity degree. We also evaluate the performance of MAM by comprehensive simulations.     

大数据环境下多源异构数据的访问控制模型

大数据平台具有开放性和共享性，但随着数据量不断增加且用户访问上下文环境复杂多变，RBAC模型难以满足大数据环境下细粒度、灵活的访问控制。针对这一问题，提出了大数据平台下多源异构数据的访问控制模型。该模型根据属性动态地确定角色权限，并构建基于数据组的层次结构，实现数据属性的简单管理。对该模型进行了形式化定义，阐述了在 Hadoop 平台中的实现和工作流程，并通过实验验证了所提方案的性能开销相对较小。     

基于混合覆盖网的可靠应用层组播方案

现有的应用层组播协议根据覆盖网的构建方法可分为网优先和树优先两种.提出了一种网.树混合的可靠应用层组播方案即M-THROM,该方案模型由一个核心网和多个附加树组成,包括了差错控制机制及拥塞控制机制,适合于大规模、低时延的可靠数据传输服务.仿真实验结果表明,该方案继承了网优先和树优先两种协议各自的优点,有良好的扩展性与较低的控制成本.     

面向QoS的域间实时流覆盖组播方法研究

针对跨域远程协作中的实时流通信质量问题,构建了实时流服务网格（LSSG）,这是一个可扩展的且面向用户QoS需求的覆盖组播通信中间件结构,LSSG服务由网络服务提供商策略部署的服务代理（SvB）提供。论文主要采用面向QoS的域间覆盖组播算法（QIOM）来组织SvB建立实时流组播服务树,根据用户服务质量请求提供跨自治系统的实时流组通信服务,将域间资源管理转变为流媒体应用的动态协同服务管理。仿真结果表明QIOM能有效地发现和提供QoS满意的覆盖服务及实现SvB间的覆盖流量负载平衡。     

基于主机的跨网段多播系统设计

多播是一种重要的群组通信技术,在许多领域正得到越来越广泛的应用.传统的多播服务由于实现在TCP/IP协议的网络层,跨网段的多播需要路由器的支持.给出了一种基于主机端应用程序的跨网段多播解决方案,在不改变现有网络结构的基础上,为处于不同子网的主机提供了群组通信服务.详细阐述了该解决方案的设计思想以及适用情况.     

Distributed multi-source streaming models in peer-to-peer overlay networks

A multimedia contents are distributed to peer computers (peers) and a contents peer which holds contents can provide other peers with the contents in peer-to-peer (P2P) overlay networks. Here, contents peers are mainly realized in less-reliable and low-performance personal computers. Multimedia streaming is more significant than downloading ways in multimedia applications from security and economical reasons. We discuss distributed multi-source streaming models to support peers with reliable and scalable multimedia streaming service. Here, a collection of multiple contents peers in parallel transmit packets of a multimedia content to a leaf peer to realize the reliability and scalability. Each of the contents peers send different packets from the other contents peers at slower rate. Even if not only some number of peers stop by fault and are degraded in performance but also some number of packets are lost and delayed in networks, a leaf peer has to receive every data of a content at the required rate. We discuss how to replicate data of a multimedia content by creating a parity packet for some number of packets and to allocate packets to each contents peer so that a leaf peer can deliver a packet without waiting for preceding packets from other contents peers in presence of the faults. Next, multiple contents peers are required to be synchronized to send packets to a leaf-peer so that the leaf-peer can receive every data of a content at the required rate. We discuss a pair of gossip-based flooding-based protocols, directed acyclic graph (DAG)-based coordination protocol (DCoP) and tree-based (TCoP) coordination protocol to synchronize multiple contents peers to send in parallel send to a leaf peer. First, some number of contents peers are selected and start transmitting packets to a leaf peer. Then, each of the selected peers selects some number of peers. Here, a peer can be selected by multiple peers in DCoP but by at most one peer in TCoP. Finally, every contents peer transmits packets to the leaf peer at the allocated rate. We evaluate the coordination protocols DCoP and TCoP in terms of how long it takes and how many messages are transmitted to synchronize multiple contents peers.     

Prioritized overlay multicast in mobile ad hoc environments

Many proposed routing protocols for manets require nodes to maintain and update complicated route information, which incurs significant overhead when groups have different priorities. To address this problem, some researchers have begun focusing on application-layer, or overlay, multicast in which an overlay network forms a virtual network consisting of only member nodes atop the physical infrastructure. We propose a prototype of prioritized overlay multicast for manets in which participating nodes can carry out multiple functions and thus be associated with more than one overlay tree.     

基于Overlay网络的应用层组播系统的研究与实现

提出了一个基于覆盖网(Overlay Network)技术的应用层组播系统。它在Pastry构建的Overlay网络上实现,由Pastry支持完成应用层的路由和组播组的发布工作,同时利用Pastry的自组织功能来增强组播系统的鲁棒性。系统基于代理的结构,利用转发树的根节点进行集中式控制和管理组播组的创建,组成员的加入、离开、组播和失效等行为,在构建组播转发树时考虑到满足不同接收者对延时和带宽的不同要求,能够较好地支持实时的组播应用。     

覆盖组播的最小覆盖代价路由算法

与IP组播相比,覆盖组播通常会消耗更多的底层网络资源。因此,在覆盖网中构造组播转发树时,考虑合理地利用底层网络资源具有一定的实际意义。给出覆盖代价的概念,把覆盖组播路由问题归结为求无向完全图的度和延迟受限、具有最小覆盖代价的生成树问题,求解的目标是在满足应用需求和端用户主机性能要求的同时使所消耗的底层网络资源最少。给出了求解该问题的启发式遗传算法,通过仿真实验验证了该算法的有效性。     

适用于多源IP组播的安全访问控制协议

目前针对IP组播的安全访问控制问题的解决方案只是实现了对组播接收者的访问控制。为此,提出了一个广泛地适用于多源IP组播的安全访问控制协议(Multi-source Multicast Access Control,MMAC)。协议通过引入专门的管理主机和管理频道实现了对组播参与者(发方和收方)及不可信路由器的安全访问控制。最后对MMAC协议的有效性和安全性进行了分析。     

基于覆盖组播的应用层组通信服务系统

网络层组播是提供一对多或者多对多通信的最佳方式,但是由于其在技术上和非技术上的原因难以在Inteme上部署。设计和实现了一种基于覆盖组播的组通信服务系统,为组通信应用提供组播服务。这个系统独立于路由器的组播机制,能够快速实现与应用系统的集成,而且能够利用多种传输协议,为构建基于Internet的组通信应用系统提供了有效的支持。     

基于树与环应用层组播覆盖网的研究与比较

由于应用层组播在部署和实现方面的优势受到学术界的广泛关注.应用层组播协议在不同的覆盖网络拓扑结构(如树、网、环)下具有不同的性能特征.因此,比较应用层组播覆盖网的性能是评估覆盖网络拓扑优缺点的关键.在NS-2下对基于树、环的覆盖网络进行仿真.仿真结果表明,尽管环型覆盖网比树型覆盖网具有较高路径伸展度和较高链路强度,但在单个组播组成员失效或离开的情况下,它提供了恒定的、更低的节点度和较高数据传送率.     

一种改进的多源异构告警聚合方案

各类网络安全防御设备产生的大量冗余告警信息非常琐碎、误警率高, 给告警的分析和理解造成较大困难。针对这一问题进行研究, 提出一种改进的多源异构告警数据的聚合方案, 综合分析告警类型、源IP、目的IP、目的端口及时间间隔几个属性, 总结出四个规则, 并在聚合过程中动态更新时间间隔阈值, 提高聚合精确度。实验结果表明, 这种方法能高效减少异构告警信息的数量, 得到精简的超告警数据, 并实现了实时处理告警信息的能力。     

An overlay multicast protocol for live streaming and delay-guaranteed interactive media

In many collaborative multimedia applications, there is often a requirement for simultaneously supporting live streaming and shareable interaction. A major challenge in designing such an application by overlay multicast is how to simultaneously provide scalable live streaming and delay-guaranteed interactive media. Live streaming by overlay multicast incurs additional application-layer latency, which conflicts with the delay-sensitive property of interactive media. To handle this dilemma, in this paper, we propose a layered degree-constrained overlay multicast protocol, which organizes the overlay multicast tree as a layered degree-constrained core tree and an extended tree. The core tree maintains available resources in its top layers for subsequent two-way interaction, whereas the extended tree expands the core tree for one-way live streaming. Our simulation and experimental results show that the proposed overlay multicast protocol can simultaneously provide delay-guaranteed interactive media as well as scalable live streaming.     

符合GSAKMP的覆盖多播水印协议的设计与分析

GSAKMP 是为多播群组安全所设计的一个密钥管理协议框架.在分析了 GSAKMP 密钥相关机制的基础上,结合多播水印的知识,对包括数据保密性和版权保护的安全覆盖多播水印协议的设计进行了研究,该协议适用于需要进行泄漏跟踪的流媒体传输.     

GMAC: An overlay multicast network for mobile agent platforms

The lack of proper support for multicast services in the Internet has hindered the widespread use of applications that rely on group communication services such as mobile software agents. Although they do not require high bandwidth or heavy traffic, these types of applications need to cooperate in a scalable, fair and decentralized way. This paper presents GMAC, an overlay network that implements all multicast related functionality–including membership management and packet forwarding–in the end systems. GMAC introduces a new approach for providing multicast services for mobile agent platforms in a decentralized way, where group members cooperate in a fair way, minimize the protocol overhead, thus achieving great scalability. Simulations comparing GMAC with other approaches, in aspects such as end-to-end group propagation delay, group latency, group bandwidth, protocol overhead, resource utilization and failure recovery, show that GMAC is a scalable and robust solution to provide multicast services in a decentralized way to mobile software agent platforms with requirements similar to MoviLog.