在下一代网络中实现多媒体会议的研究

下一代网络中包含有各种网络,例如因特网、PSTN电话网和无线通信网。为了在不同的网络设备间提供统一的多媒体会议业务,该文结合SIP、VoiceXML和SIP会议技术提出了一种新架构,并明确了相关网络实体间的信令流程。     

Some Issues on Computer Networks: Architecture and Key Technologies

The evolution of computer networks has experienced several major steps, and research focus of each step has been kept changing and evolving, from ARPANET to OSI/RM, then HSN （high speed network） and HPN （high performance network）. During the evolution, computer networks represented by Internet have made great progress and gained unprecedented success. However, with the appearance and intensification of tussle, along with the three difficult problems （service customizing, resource control and user management） of modern network, it is found that traditional Internet and its architecture no longer meet the requirements of next generation network. Therefore, it is the next generation network that current Internet must evolve to. With the mindset of achieving valuable guidance for research on next generation network, this paper firstly analyzes some dilemmas facing current Internet and its architecture, and then surveys some recent influential research work and progresses in computer networks and related areas, including new generation network architecture, network resource control technologies, network management and security, distributed computing and middleware, wireless/mobile network, new generation network services and applications, and foundational theories on network modeling. Finally, this paper concludes that within the research on next generation network, more attention should be paid to the high availability network and corresponding architecture, key theories and supporting technologies.     

Distributed information service architecture for overlapping multiaccess networks

Multimedia delivery in mobile multiaccess network environments has emerged as a key area within the future Internet research domain. When network heterogeneity is coupled with the proliferation of multiaccess capabilities in mobile handheld devices, one can expect many new avenues for developing novel services and applications. New mechanisms for audio/video delivery over multiaccess networks will define the next generation of major distribution technologies, but will require significantly more information to operate according to their best potential. In this paper we present and evaluate a distributed information service, which can enhance media delivery over such multiaccess networks. We describe the proposed information service, which is built upon the new distributed control and management framework (DCMF) and the mobility management triggering functionality (TRG). We use a testbed which includes 3G/HSPA, WLAN and WiMAX network accesses to evaluate our proposed architecture and present results that demonstrate its value in enhancing video delivery and minimizing service disruption in an involved scenario.     

Access and service convergence over the mobile internet – A survey

Next generation heterogeneous wireless networks are expected to interwork with Internet Protocol (IP)-based infrastructures. Conventional network services operate like silos in that a specific set of services are offered over a specific type of access network. It is desirable for users to be able to roam between fixed and mobile networks that employ different access technologies. Therefore, mobility management with quality of service (QoS) support is of particular importance and one of the driving forces of convergence. Since service providers often provide more than one service to their subscribers, it is important to facilitate convergence of network charging architecture through a common charging framework. One of the main issues of IP-based convergence is security and privacy. This requires coordination of different security policies in diverse networks that have different security levels and capabilities. The business case for migration to an IP-based platform motivates operators to deliver more powerful services for customers as well as a better user experience. This paper provides an overview of converged mobile Internet architectures and their implications on QoS, charging/billing and security, as well as emerging business models for telecommunication services.     

Dynamic Partitioning and Popularity based Caching for Optimized Performance in content-centric fog networks: DPPCOP

With the massive growth of information generation, processing, and distribution in the Internet of Things (IoT), the existing cloud architectures need to be designed more effectively using fog networks. The current IP-address-based Internet architecture is unable to deliver the desired Quality-of-Service (QoS) towards the increasing demands of fog networking-based applications. To this end, Content-Centric Networking (CCN) has been developed as the potential future Internet architecture. CCN provides name-based content delivery and is established as an architecture for next-generation fog applications. The CCN-based fog environment uses the cache of in-network fog nodes to place the contents near the end-user devices. Generally, the caching capacity of the fog nodes is very small as compared to the content catalog size. Therefore, efficient content placement decisions are vital for improving the network performance. To enhance the content retrieval performance for the end-users, a novel content caching scheme named “Dynamic Partitioning and Popularity based Caching for Optimized Performance (DPPCOP)” has been proposed in this paper. First, the proposed scheme partitions the fog network by grouping the fog nodes into non-overlapping partitions to improve content distributions in the network and to ensure efficient content placement decisions. During partitioning, the scheme uses the Elbow method to obtain the “good” number of partitions. Then, the DPPCOP scheme analyzes the partition’s information along with the content popularity and distance metrics to place the popular contents near the end-user devices. Extensive simulations on realistic network topologies demonstrate the superiority of the DPPCOP caching strategy on existing schemes over various performance measurement parameters such as cache hit ratio, delay, and average network traffic load. This makes the proposed scheme suitable for next-generation CCN-based fog networks and the futuristic Internet architectures for industry 4.0.     

一种基于QoS的Internet服务管理体系结构

服务定位协议(SLP)是IETF提出的基于IP网络的服务定位标准。而这一标准并没有考虑对QoS的支持。未来的互联网络是一个具有QoS保证的网络。服务发现仅仅是Internet服务管理中的一个方面，发现服务不是最终目的，最终目的是为了使用这一服务。在对SLP体系结构、下一代互联网QoS服务管理及相关技术充分研究的基础上，提出了一种新奇的基于QoS的Internet服务管理体系结构模型。为使在服务表示与发现层支持QoS，对SLP定位协议进行了一些扩充。对服务定位协议扩充后，当用户代理在向服务代理发布请求时，可以在请求消息中绑定QoS对象参数，一旦服务代理接收到这一消息，就可以利用这些QoS参数与域管理器进行协商，协商结果可通过服务代理反馈给用户代理。这样不仅减小了网络开销，而且降低了传统的用户代理与域管理器协商的次数，在服务发现的同时用户代理还可以直接获得该服务的QoS信息。     

软件定义网络安全问题研究综述

软件定义网络是一种新型的网络体系结构,其通过OpenFlow技术来实现网络控制面与数据面的分离,从而达到对网络流量的灵活控制,目前已成为下一代互联网的研究热点.随着SDN的发展及广泛应用,其安全问题已成为亟待解决的重要研究内容.近年来,国内外学者在SDN安全研究领域取得了一定的成果,文中针对SDN的3层架构分别对各层所...     

移动边缘网络中计算迁移与内容缓存研究综述

随着移动设备数量的爆炸性增长以及许多新兴应用的出现,移动网络的流量呈指数级增长.传统的集中式网络架构由于回程链路负载过重、时延较长,无法满足移动用户的需求.因此,提出了将网络能力从核心网开放至边缘网的新体系结构,即移动边缘计算（MEC）.移动边缘计算能够在移动蜂窝网络的边缘提供轻量级的云计算和存储能力.对移动边缘计算相关的最新研究成果进行了详尽的回顾：首先,概述了移动边缘计算的发展历程、关键问题和支撑技术;然后,针对MEC架构、计算迁移、边缘缓存和服务编排这4个关键研究问题进行了全面的综述,并讨论了增强现实、虚拟现实、动态内容交付、车联网和物联网等移动边缘计算中的典型应用案例;最后,从移动边缘计算功能增强、服务质量保障和安全可用性这3个方面展望了移动边缘计算的开放式研究挑战和未来的发展趋势.     

基于虚接口的移动IPv6协议的设计与实现

随着基于无线接入的IP业务应用需求不断增长,在下一代互联网中实现对移动性的支持变得越来越重要．本文介绍了在面向边缘网络接入应用的IPv6路由器原型系统中移动IPv6协议的具体实现．为了实现这一协议,文章分析了移动IPv6协议的特点,并借鉴虚拟网络（Virtual Networks）的思想提出了基于虚接口的设计和实现方岳,其主要优点是降低了协议开发的复杂度．该方法也可以用于实现其它的Internet高层协议．     

Toward the mobile Internet

The promise of ubiquitous computing is a future in which highly specialized, embedded computing devices operate seamlessly within the everyday environment and are transparent to users. Realizing this vision will require next-generation networks to support mobile multimedia devices with capabilities well beyond those of today's handsets. These networks will exploit wideband radio access technologies and IP-based protocols to provide IP transparency-all network elements support IP; mobility management for a globally networked environment; unique addressing for every user; personalization of information; positioning to enable location-dependent services; and end-to-end security. Such functionality requires more than providing wireless Internet access and e-mail.     

网络创新试验床关键技术综述

为解决TCP/IP面临的可扩展性、动态性和安全可控性等问题,研究人员提出了大量的新型网络体系架构、协议和算法等,而这些研究在部署与应用前需要在一定规模的、逼近于真实网络的试验床上进行长时间的测试、评估和优化.近年来,国内外兴起了网络创新试验床的研究和建设.然而,网络创新试验床在设计与实现中面临一系列挑战.以实验所面临的成本、可行性、可信性和可控性4个问题为出发点,总结了网络创新试验床的需求及特性要求,归纳分析了其在虚拟化、网络可编程性、联邦管控、实验控制、测量与监测等方面存在的技术挑战,并对关键技术、架构和研究进展进行介绍与论述.最后分析了国内外网络创新试验床的建设与发展现状,并讨论了网络试验床未来的发展趋势和需要进一步解决的问题.     

移动多用户ATM平台的体系结构与设计关键

论述的主要问提是 :可移动多用户平台的特点、基本网络单元的体系结构问题、在ATM网中子网的可移动性、移动平台的位置管理、在移动平台中多用户的交接。讨论了所提出网络体系结构和协议的可用性 ,并为可移动多用户平台的特殊问题提出了一些解决方法。     

基于GIG应用的服务质量体系结构研究

针对网络中不同服务质量体系结构以及它们在GIG(Global Information Grid)网络技术中的应用;首先分析了现有网络中的服务质量体系结构,通过比较不同的服务质量结构在GIG网络技术中的应用,提出了详细的分析结果;其次,对GIG中的三种网络组成部分,MANET、卫星网络和GIG带宽扩展,以及与之相对应的服务质量体系结构进行了正确的评估;最后,通过分析它们之间的相互影响,提出了基于GIG的端对端的服务质量体系结构;深入研究全球信息栅格服务质量体系结构技术对于提高我军信息化建设水平,推进以信息技术革命为主体的新军事革命,具有十分重要的意义。     

基于快速连续蚁群算法的QoS切换决策机制

随着人们对移动网络服务需求的日益增长,用户需要在复杂的异构网络中实现不同接入技术之间的无缝切换,因此选择总最佳连接并提供服务质量保证的切换决策成为下一代互联网研究的关键内容.为了更好地满足用户的需求,在综合考虑网络信息的不确定性、用户服务质量需求、用户偏好、用户愿意支付的费用以及网络供应商的收益等因素的前提下,设计了基于快速连续蚁群算法的切换决策机制,并引入协商博弈和Nash均衡思想来解决用户之间的串谋问题以保证切换决策的公平性.仿真结果表明,设计的切换决策机制在满足用户服务质量需求的同时,不仅使双方的效用最大,并且最契合用户的偏好,能够很好地解决下一代互联网中支持总最佳连接的切换决策问题.     

Context-aware control of user-centric virtual networks: Centralized vs distributed approaches

Recently, the Internet has been overrun by a diversity of devices, applications, technologies, and Internet users with increasingly demanding personal preferences. Due to the explosive growth of Internet usage, the quantity of context information available in networking environments is also growing rapidly, triggering research for novel architectures and protocols that are enriched or personalized based on the particular features and dynamics of such information.This article describes a virtualized architecture that splits a physical network infrastructure into a set of logical networks (or Virtual Networks – VNs) configured to meet the particular context needs of their attached users (in terms of, e.g., price, security or services’ quality). Since this architecture can be driven by volatile context needs of highly mobile users, we also present the signaling mechanisms to create, extend and remove VNs in response to user context dynamics and mobility, which can be performed in a centralized or distributed way. Further, we define and evaluate context-aware metrics to configure a VN, and discover and select VNs to assign to users or network paths.The evaluation of the proposed approach shows that distributed approaches allow the fast discovery and adaptation of VNs, at the cost of a slightly larger overhead than centralized approaches when the context dynamics are too high. We also assess the impact of considering distinct levels of knowledge distribution and user context dynamics on the design and behavior of several processes for user association and VN control. Finally, we observe that context-driven VN discovery and resource-aware path selection schemes outperform the ones that, respectively, flood the network with VN discovery requests or use shortest path-based strategies to adapt VNs.     

User-centric mobility management for multimedia content access

Current mobility protocols and architectures are mainly targeted to devices or applications and they usually lack the ability to support user-centric paradigms; moreover, they usually face a single aspect of the problem, i.e., terminal handover or session mobility. Full mobility support is only available to specific applications or protocols (e.g., SIP) but these approaches do not exploit all facilities for movement detection at the network/link layers and do not allow to use the same framework for different applications. This paper proposes a generic mobility framework for terminal handover and session migration. It pursues the user-centric paradigm and builds a cross-layer architecture, yielding to a high level of generality, applicability and flexibility. Unlike other approaches, it does not require any modification in correspondent peers and works with a minimal network infrastructure. Software implementations are described for two representative real-time multimedia applications, i.e., media streaming and interactive conference. The effectiveness of the framework was analyzed by means of both performance measurements in local and Internet testbeds and user evaluation during a live demo conducted at a national science exhibition.     

Double-sided auctions applied to vertical handover for mobility management in wireless networks

In the next generation Internet, we have seen the convergence of multimedia services and Internet with the mobility of users. Vertical handover decision (VHD) algorithm are essential components of the mobility management architecture in mobile wireless networks. VHD algorithms help mobile users to choose the best mobile network to connect among available candidates. It also can help the network manager to optimize easily the limited resources shared among the network providers and the users. In this article, we formulate VHD algorithm as a resource allocation problem for down-link transmission power in multiple W-CDMA networks and show how combinatorial double-sided auctions can be applied to this specific problem. The proposed pricing schemes make use of the signal interference to noise ratio, achievable data rates, power allocation at mobile networks, and monetary cost as decision criteria and our model differentiate between new calls and on-going communications to take into account that the last category has somewhat more importance. Several combinatorial double-sided auction are proposed to maximize the social welfare and /or to provide incentives for mobile users and mobile operators to be truth-telling in terms of valuation or cost. Finally, the economic properties of the different proposed pricing schemes are also studied by means of simulations.     

A mobility management scheme for wireless mesh networks based on a hybrid routing protocol

Recent advances in wireless mesh networks (WMNs) have overcome the drawbacks of traditional wired networks and wireless ad hoc networks. WMNs will play a leading role in the next generation of networks, and the question of how to provide seamless mobility management for WMNs is the driving force behind the research. The inherent characteristics of WMNs, such as relatively static backbones and highly mobile clients, require new mobility management solutions to be designed and implemented.In this paper, a hybrid routing protocol for forwarding packets is proposed: this involves both link layer routing and network layer routing. Based on the hybrid routing protocol, a mobility management scheme for WMNs is presented. Both intra-domain and inter-domain mobility management have been designed to support seamless roaming in WiFi-based WMNs. During intra-domain handoff, gratuitous ARP messages are used to provide new routing information, thus avoiding re-routing and location update. For inter-domain handoff, redundant tunnels are removed in order to minimize forwarding latency. Comprehensive simulation results illustrate that our scheme has low packet latency, low packet loss ratio and short handoff latency. As a result, real-time applications over 802.11 WMNs such as VoIP can be supported.     

未来互联网虚拟化研究

目前的互联网基于“端到端”原则设计,并且由许多目标与策略迥异的互联网服务提供商共同创建和维护.若想升级互联网体系结构,需要得到他们全体的一致同意,因此几乎不可能在互联网上部署全新的网络结构和协议.为了避免互联网结构出现僵化,人们提出可用网络虚拟化方法增加互联网范式的多样性.通过在一个公共的基底网络上引入多种不同的互联网结构,互联网虚拟化可以促进互联网创新并推动更多种类的新应用出现.分别从互联网体系结构和实验平台2个方面,对过去和当前正在进行的有关未来互联网的虚拟化研究进行分析、归类和概述,并总结未来互联网虚拟化研究的发展趋势.