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.     

A conceptual model of service customization and its implementation

With the development of Internet and next generation networks in telecommunications, more and more new services are required to be introduced into networks. Introducing new services into traditional network is always associated with standardizing new protocols. The progress of protocol standardization usually takes several years, which cannot meet the increasing demands of the applications in Internet and next generation networks. Service customization in network systems may be one possible solution to cope with this problem. Based on the principle that network service is provided by interactions among protocol entities, this paper proposes a conceptual model of service customization (SECUM) by separating the service logic from protocol interactive logic within existing network architecture. The theory of Communicating Sequential Processes (CSP) is used to formalize the SECUM in order to locate exactly the service logic and to define precisely the SECUM. For validating the SECUM‘s usability in practical network systems, this paper also proposes an implementation model for SECUM: a component-based protocol implementation model (CPIM). CPIM discomposes protocol entity into application component, service component, message component and communication component. Service component associates application component with message component. Users or network managers can customize network services by configuring service component. The paper shows respectively the applications of SECUM and CPIM by proposing a customizable IP service model based on SECUM and describing an implementation of Session Initiation Protocol (SIP) based on CPIM. Compared with the existing service-customization techniques, SECUM is a service customization model internal to network system and may provide more powerful capabilities of service customization.     

Utility-based bandwidth allocation algorithm for heterogeneous wireless networks

In next generation wireless network (NGWN), mobile users are capable of connecting to the core network through various heterogeneous wireless access networks, such as cellular network, wireless metropolitan area network (WMAN), wireless local area network (WLAN), and ad hoc network. NGWN is expected to provide high-bandwidth connectivity with guaranteed quality-of-service to mobile users in a seamless manner; however, this desired function demands seamless coordination of the heterogeneous radio access network (RAN) technologies. In recent years, some researches have been conducted to design radio resource management (RRM) architectures and algorithms for NGWN; however, few studies stress the problem of joint network performance optimization, which is an essential goal for a cooperative service providing scenario. Furthermore, while some authors consider the competition among the service providers, the QoS requirements of users and the resource competition within access networks are not fully considered. In this paper, we present an interworking integrated network architecture, which is responsible for monitoring the status information of different radio access technologies (RATs) and executing the resource allocation algorithm. Within this architecture, the problem of joint bandwidth allocation for heterogeneous integrated networks is formulated based on utility function theory and bankruptcy game theory. The proposed bandwidth allocation scheme comprises two successive stages, i.e., service bandwidth allocation and user bandwidth allocation. At the service bandwidth allocation stage, the optimal amount of bandwidth for different types of services in each network is allocated based on the criterion of joint utility maximization. At the user bandwidth allocation stage, the service bandwidth in each network is optimally allocated among users in the network according to bankruptcy game theory. Numerical results demonstrate the efficiency of the proposed algorithm.     

Decrement delay with widest K-shortest paths Q-routing algorithm

During the last few years the Internet has grown tremendously and has penetrated all aspects of everyday life. Starting off as a purely academic research network, the Internet is now extensively used for education, for entertainment, and as a very promising and dynamic marketplace, and is envisioned as evolving into a vehicle of true collaboration and a multi-purpose working environment. Although the lnternet is based on a best-effort service model, the simplicity of its packet-switched design and the flexibility of its underlying packet forwarding regime （IP） accommodate millions of users while offering acceptable performance. At the same time, exciting new applications and networked services have emerged, putting greater demands on the network. In order to offer a better-than-best-effort Internet, new service models that offer applications performance guarantees have been proposed. While several of these proposals are in place, and many QOS-enabled networks are operating, there is still a lack of comprehension about the precise requirements new applications have in order to function with high or acceptable levels of quality. Furthermore, what is required is an understanding of how network-level QOS reflects on actual application utility and usability. In this work a proposal for routing which improves the delay factor and is based on the reinforcement learning is concerned. We use Q-learning as the reinforcement learning technique and introduce K-shortest idea into the learning process. The proposed algorithm is applied to two different topologies. The OPNET is used to evaluate the performance of the proposed algorithm. The algorithm evaluation is done for two traffic conditions, namely low load and high load.     

分布式视频点播系统的接入控制研究

Video on Demand(VoD)systems are considered as one of the most valuable services for the next generation broad-bandwidth Internet. To provide high-quality service, the VoD system must employ an admission control module to guarantee QoS, but there are still less research works having been made in this field, especially for distributed VoD systems. In this paper, we mainly focus on distributed admission control for VBR video streams in distributed VoD systems. We firstly discuss different approaches and then two admission control strategies are proposed with experimental comparisons. Our research is also further extended to resource assignment in distributed VoD systems. At the end of this article, we address issues in implementing distributed admission control.     

A lightweight authentication scheme with user untraceability

With the rapid growth of electronic commerce and associated demands on variants of Internet based applications,application systems providing network resources and business services are in high demand around the world.To guarantee robust security and computational efficiency for service retrieval,a variety of authentication schemes have been proposed.However,most of these schemes have been found to be lacking when subject to a formal security analysis.Recently,Chang et al.(2014) introduced a formally provable secure authentication protocol with the property of user-untraceability.Unfortunately,based on our analysis,the proposed scheme fails to provide the property of user-untraceability as claimed,and is insecure against user impersonation attack,server counterfeit attack,and man-in-the-middle attack.In this paper,we demonstrate the details of these malicious attacks.A security enhanced authentication scheme is proposed to eliminate all identified weaknesses.     

Trustworthy assurance of service interoperation in cloud environment

Cloud computing can be realized by service interoperation and its essence is to provide cloud services through network. The development of effective methods to assure the trustworthiness of service interoperation in cloud environment is a very important problem. The essence of cloud security is trust and trust management. Combining quality of service (QoS) with trust model, this paper constructs a QoS-aware and quantitative trust-model that consists of initial trust value, direct trust value, and recommendatory trust value of service, making the provision, discovery, and aggregation of cloud services trustworthy. Hence, it can assure trustworthiness of service interoperation between users and services or among services in cloud environment. At the same time, based on this model, service discovery method based on QoS-aware and quantitative trust-model (TQoS-WSD) is proposed, which makes a solid trust relationship among service requestor, service provider and service recommender, and users can find trustworthy service whose total evaluation value is higher. Compared to QoS-based service discovery (QoS-WSD) method, it is proved by the experiment for TQoS-WSD method that more accurate result of service discovery will be achieved by service requestor, while reasonable time cost is increased. Meanwhile, TQoS-WSD method strongly resists the effect of service discovery by untrustworthy QoS values and improves service invocation success-rate and thus assures trustworthiness of services interoperation.     

基于Internet的视频代理缓存服务器设计的若干关键问题

With the boom of the network technology, all kinds of services based on the Internet come into being. A-mong them, the most promising one is the video service. All of this kind of service has been paid much attention,such as videoconference and video-on-demand. Because of the instability of the Internet environment, the traditional Client/Server mode in the LAN, which is used to support the data transmission, is not suitable any longer. And the newly designed Server/Proxy/Client one is more effective. This paper describes this architecture and its service pat-tern, does some deep research on the key issues of the design of the proxy cache server, such as the caching and re-olacernent nlr the viden data, the management and coordination of multi-proxy-servers.     

Study of Network Traffic Analysis Model Based on Time Granularity

An analytic research on establishing different traffic models on the traffic nature of different time granularity can provide necessary academic foundation for network design and simulation as well as ensuring the quality of service and network management. This paper aims to make simulant predication by means of corresponding math tools on the modeling of real traftic of the different time granularity. The experimental results indicate that the predicated traffic is close to the real traffic distribution.     

A measurement approach of trust relation in web service

With the advent and proliferation of web services, quality of service serves as a benchmark to differentiate and select the services. Because trust has been regarded as an essential security relationship within a distributed network environment, quality evaluation of services from the viewpoint of trust presents a significant trend in decision support for selecting service over Internet. Unfortunately, the current research in the context of web services does not accurately reflect the randomness and fuzziness of trust, the basic issue in related research about trust. In this paper, we designed two kinds of trust cloud based on cloud model theory to describe the randomness and fuzziness of trust factors. Furthermore, a formalized calculation was provided to obtain the trust degree. To our knowledge, this is the first investigation into trust of web Service considering the integration of randomness and fuzziness, and applying the cloud model to quantitative evaluation of trust in the field of web services.     

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。     

Internet服务管理技术综述

1 服务与服务的分类经常提到服务这个概念,那么到底什么是服务呢?文[1]对服务进行了定义:服务就是服务提供方向一个或多个所服务的用户提供的一组实际能力。为研究之便,我们将服务分成两类:一类是传输服务,另一类是应用服务。这两种服务并不完全独立,它们是相互依存的,其中传输服务是应用服务的基础与保证,而应用服务是对传输服务的一种增值与体现。应用     

一种面向视频业务的拥塞控制策略

近年来，因特网上的视频业务得到了广泛的发展。如何在异构的IP网上为用户提供满足QoS要求的视频服务，一直是人们研究的热点。本文提出了一种新的拥塞控制策略--基于分层重要性的队列管理和基于丢包检测的速率控制。仿真结果表明，该方法可以在网络拥塞情况下，为视频业务提供较好的QoS保证。     

Computational intelligence tools for next generation quality of service management

In this paper we explore the interest of computational intelligence tools in the management of heterogeneous communication networks, specifically to predict congestion, failures and other anomalies in the network that may eventually lead to degradation of the quality of offered services. We show two different applications based on neural and neuro-fuzzy systems for quality of service (QoS) management in next generation networks for voice and video service over heterogeneous Internet protocol (V2oIP) services. The two examples explained in this paper attempt to predict the communication network resources for new incoming calls, and visualizing the QoS of a communication network by means of self-organizing maps.     

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.     

基于分类服务的下一代互联网体系结构的实现

随着互联网应用的增长,目前提供尽力服务的互联网体系结构越来越不能满足这些新的服务要求。通过设计出一种新的路由器缓冲区管理策略,探讨一种基于分类服务的新一代互联网体系结构的实现方式。     

基于网关的ZigBee网络与Internet互联框架

针对如何将ZigBee网络与Internet紧密融合的问题,提出一种网关设计方案.介绍了工作在传输层的互联网关,在分析此网关不足的基础上,根据面向服务的网络中间件思想,提议网关的体系结构.包括服务注册、服务绑定、服务调用和取消服务4个模块,以实现为用户提供服务的透明性;同时,为了减少ZigBee网络节点占用的IP地址数目,服务调用模块中使用传输层网关的协议转换方式.该网关从网络协议和服务两个角度实现ZigBee网络和Internet网络的互联,通过分析和比较证明具有用户透明性、业务提供方便等特点.     

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.     

关于切换技术解决3G网络融合问题的综述

通过对无线通信网络的体系结构,运营方式,切换技术实现细节等方面的分析和研究,研究和探讨异构网络之间的切换技术,最终提出一个面向下一代无线通信网络的新型的基于IP的综合切换(Integrated Handover,IH)框架。IH技术的最终目标就是要解决移动通信网络中因网络异构、资源开销瓶颈等影响,成功地实现全球无线网络覆盖范围的低时延、高带宽、宽切换域、开销低和QoS保证的不同网络间顺畅的无缝切换。