6LoWPAN无线传感器网络有状态地址配置方案*

提出一种基于分布式的6LoWPAN无线传感器网络有状态地址配置方案,其每个传感器节点都具有分配地址的权力且地址分配空间具有唯一性,从而将地址分配任务均匀地分布到每个传感器节点,实现了多个传感器节点的同时配置,提高了地址分配效率;同时,节点申请地址的控制信息的传输范围均控制在一跳范围内,降低了地址配置功耗,缩短了地址配置时间,延长了网络寿命。对所提方案与MANETConf、Strong DAD及LISAA的地址配置代价及地址配置延迟时间等性能参数进行了比较分析,分析结果验证了此方案的可行性和高效性。     

DIAMETER移动IPv6应用扩展方案

该文在DIAM ETER移动IPv6应用扩展基本模型的基础上,针对IPv6的无状态和DH CP有状态两种地址自动配置方式,分别在接入路由器和DH CP服务器上进行AAA功能扩展,给出了相应的DIAM ETER移动IPv6应用扩展方案。之后提出一个将两种地址自动分配方式结合使用的DIAM ETER移动IPv6 AAA解决方案,既可以减少移动节点跨域移动的时延,又便于网络资源的统一分配。文章最后给出了已实现的无状态地址分配方式下DIAM ETER移动IPv6AAA系统的实验结果,从而证明了所提方案的有效性。     

Mobility management solution for IPv6-based vehicular networks

This paper proposes a mobility management solution for IPv6-based vehicular networks. First, the architecture based on vehicle domains is proposed in order to reduce the mobility handover frequency and delay. Based on the architecture, a distributed address configuration algorithm is proposed. Based on the address configuration algorithm, a vehicle can establish a routing path reaching the nearest AP (Access point) and achieve the multi-hop communication with the Internet through the routing path. Finally, based on the routing algorithm, the mobility management solution is proposed. The data results show that the solution shortens the mobility handover delay and lowers the packet loss.     

基于IPv6的城市车载网移动协议

提出了一种基于IPv6的城市车载网移动切换协议。本协议提出了城市车载网络体系结构, 车辆节点在移动过程中由家乡地址唯一标志, 无须转交地址, 因此节省了转交地址配置时间和代价, 从而缩短了移动切换时间, 降低了移动切换代价。车辆节点无须参与移动切换过程, 从而避免了由于车辆节点高速行驶引起丢包而增加移动切换代价和延迟的情况。仿真数据结果表明该方案的性能更好。     

基于Linux环境的IPv6的自动配置分析及实验

针对对IPv6的特点和各种地址配置认识的不足,列出IPv6较IPv4主要增加的特点,介绍了IPv6无状态地址自动配置下的链路本地地址的转换原则以及在Linux环境中IPv6无状态地址自动配置下的全局地址配置、IPv6有状态地址自动配置下DHCPv6的无状态和有状态的地址自动配置的方法,以及通过使用wireshark抓包进行相应的分析、阐明各种地址配置的方法和工作流程.     

Research on IPv6 address configuration for a VANET

The paper proposes an IPv6 address configuration scheme for a VANET (Vehicular Ad hoc Network). In the paper, the VANET architecture is presented, and based on the architecture the hierarchical IPv6 address structure is created. Based on the hierarchical address structure, the distributed IPv6 address configuration scheme is proposed. In the scheme, each AP (Access Point) has the unique address space and has the right to assign an IPv6 address for an OBU (Onboard Unit). In this way, the address configuration task is distributed around all APs in a VANET, so the distribution of the address configuration is achieved. Moreover, an OBU acquires a unique IPv6 address from a neighbor AP without DAD (Duplicate Address Detection), so the transmission of the control packets used for the address configuration is controlled within one-hop scope. The paper also proposes the address recovery algorithm. Through the algorithm, an AP can retrieve the IPv6 address resources released by OBUs timely and effectively, so it has always sufficient address space for assignment. The paper evaluates the performance of the proposed scheme. The data results show that the proposed scheme reduces the address configuration cost, shortens the address configuration delay and improves the address configuration success rate.     

A tree-based address configuration for a MANET

This paper proposes an address configuration scheme for a MANET. In this paper, the tree-based architecture and the algorithm of constructing a MANET are presented. In this architecture, a proxy node can assign a unique address for neighbor new nodes, so the address configuration task is distributed around all proxy nodes. The transmission of control packets is controlled within one-hop scope, so the cost is reduced and the delay is shortened. Through this architecture, the address resources released by failed nodes can be automatically reclaimed for reuse, so a proxy node has always the sufficient address space for assignment. In order to ensure the uniqueness of a node’s address, the paper also proposes the MANET merging and partitioning algorithms. Finally, this paper evaluates the performance metrics of both the proposed scheme and the existing schemes, and the results show that the proposed scheme reduces the address configuration cost and shortens the address configuration delay.     

A stateful storage availability and entropy model to control storage distribution on grids

In spite of numerous works studying file replication strategies on distributed systems, data management policies remain mostly handled by manual operators or very basic algorithms on production grids. Among other causes, this situation is due to the lack of models taking job reliability into account. In this paper, we study file replication using new metrics to evaluate the reliability of distributed storage configurations. A stateful storage availability model is introduced to cope with the inability of the stateless model to account for the commonsense intuition that limiting the number of storage hosts involved in the execution of an application improves reliability. We describe the job success probability and the brittleness entropy, a metric describing the uncertainty of the job failure rate associated to a storage configuration. Results, obtained on synthetic data and on traces extracted from the European Grid Infrastructure, show that the stateful model is more accurate than the stateless on real data, and that it can describe the consequences of limiting the number of storage hosts on application reliability. These findings open the door to the design of new file replication strategies taking storage availability into account. Copyright © 2014 John Wiley & Sons, Ltd.     

An IPv6 address configuration scheme for wireless sensor networks

The paper proposes an IPv6 address configuration scheme for wireless sensor networks. The paper creates an IPv6 address structure for sensor nodes, and based on the proposed IPv6 address structure, the paper proposes an IPv6 address auto-configuration scheme. In the scheme, the transmission scope of the control packets is controlled within one-hop scope and the scheme neither records the address allocation status nor performs the duplicate address detection, so the address configuration cost is reduced and the address configuration delay is shortened. In addition, based on the proposed IPv6 address structure, the paper proposes the address recovery algorithm. From the perspectives of the address configuration cost and address configuration delay, the paper analyzes and compares the performance parameters of the proposed scheme and the existing schemes, including MANETConf, Strong DAD, LISAA and IAC. The analytical and simulative results show that the performance of the proposed scheme is better.     

A Scalable Asynchronous Cache Consistency Scheme (SACCS) for mobile environments

In the literature, there exit two types of cache consistency maintenance algorithms for mobile computing environments: stateless and stateful. In a stateless approach, the server is unaware of the cache contents at a mobile user (MU). Even though stateless approaches employ simple database management schemes, they lack scalability and ability to support user disconnectedness and mobility. On the other hand, a stateful approach is scalable for large database systems at the cost of nontrivial overhead due to server database management. We propose a novel algorithm, called Scalable Asynchronous Cache Consistency Scheme (SACCS), which inherits the positive features of both stateless and stateful approaches. SACCS provides a weak cache consistency for unreliable communication (e.g., wireless mobile) environments with small stale cache hit probability. It is also a highly scalable algorithm with minimum database management overhead. The properties are accomplished through the use of flag bits at the server cache (SC) and MU cache (MUC), an identifier (ID) in MUC for each entry after its invalidation, and estimated time-to-live (TTL) for each cached entry, as well as rendering of all valid entries of MUC to uncertain state when an MU wakes up. The stale cache hit probability is analyzed and also simulated under the Rayleigh fading model of error-prone wireless channels. Comprehensive simulation results show that the performance of SACCS is superior to those of other existing stateful and stateless algorithms in both single and multicell mobile environments.     

LPPTE: A lightweight privacy-preserving trust evaluation scheme for facilitating distributed data fusion in cooperative vehicular safety applications

Vehicular networks have tremendous potential to improve road safety, traffic efficiency, and driving comfort, where cooperative vehicular safety applications are a significant branch. In cooperative vehicular safety applications, through the distributed data fusion for large amounts of data from multiple nearby vehicles, each vehicle can intelligently perceive the surrounding conditions beyond the capability of its own onboard sensors. Trust evaluation and privacy preservation are two primary concerns for facilitating the distributed data fusion in cooperative vehicular safety applications. They have conflicting requirements and a good balance between them is urgently needed. Meanwhile, the computation, communication, and storage overheads will all influence the applicability of a candidate scheme. In this paper, we propose a Lightweight Privacy-Preserving Trust Evaluation (LPPTE) scheme which can primely balance the trust evaluation and privacy preservation with low overheads for facilitating the distributed data fusion in cooperative vehicular safety applications. Furthermore, we provide exhaustive theoretical analysis and simulation evaluation for the LPPTE scheme, and the results demonstrate that the LPPTE scheme can obviously improve the accuracy of fusion results and is significantly superior to the state-of-the-art schemes in multiple aspects.     

基于分布式实时机制的车载网络出行计划算法*

提出了一种基于分布式实时交通统计的机制,每辆汽车能够分布式地实时获取各路段的汽车通行时间,这样汽车就能够根据这些信息计算出行计划。仿真结果显示该方法对各路段交通情况评估具有有效性和信息扩散的实时性。     

Stateful session handoff for mobile WWW

This paper proposes a web session handoff system that can hand over not only stateless but also stateful sessions between homogenous and heterogeneous user devices to enable uninterrupted and seamless web access. The proposed system adopts a proxy-based approach and an optional client-assisted scheme in order to track and hand over session information. In the proposed system, a session is registered at a User Agent Proxy (UAP) and then tracked by the UAP so that the session can be handed over from one device via the UAP to another device. In addition to session information tracked by a UAP, the UAP can hand over more comprehensive session information by using the client-assisted scheme. Compared with client-based approaches, our design has several advantages, such as less modification to user devices, practicability, and fault tolerance. We have implemented a UAP on a PC and client programs for both PC and PDA. The implementation can successfully hand over between PC and PDA a stateful session for online shopping applications.     

A Distributed Address Configuration Scheme for a MANET

This paper proposes a distributed address configuration scheme for a Mobile Ad hoc Network (MANET). The architecture for a MANET, the algorithm of constructing a MANET, and the algorithm for calculating a unique address space for the assignment are proposed. In the architecture, a common node has a unique address space for the assignment, and an isolated node can acquire a unique address from a neighboring common node without performing duplicate address detection. In this way, the address configuration task is distributed around common nodes. In this scheme, the control packets used for address configuration are exchanged within a one-hop scope, so the scalability is enhanced. This paper also presents an address recovery algorithm that can effectively retrieve the address resources released by failed nodes and the MANET merging/partitioning algorithm that can ensure a node’s address uniqueness. This paper compares the performance parameters of the proposed scheme and the existing schemes, including strong duplicate address detection and prime dynamic host configuration protocol, and the comparative results show that the address configuration cost of the proposed scheme is lower and the delay is shorter.     

基于二部图匹配的车载网络分布式存储机制

现有的车载网络中对数据存储机制的研究大多以移动车载节点作为数据载体,然而车载节点的快速移动、存储空间有限、存在安全风险等特性,限制了车载网络数据存储性能的进一步优化.针对部署有路边基础设施的车载网络场景,以路边单元作为存储节点,提出了基于二部图匹配的车载网络分布式存储机制（distributed storage scheme,简称DSS）.在车载网络中,以最大化数据响应率为目标,路边单元的数据存储问题是NP完全问题.首先,依据请求分割规则将原问题转化为二部图最大匹配问题,其中,二部图左顶点代表车载节点的请求,右顶点代表路边单元的存储单元;进而,利用Hungarian算法在多项式时间内求得最优解.由于问题转化可能造成不同路边单元存储相同数据的冗余问题,设计了冗余副本清理算法,依据不同副本的响应因子排序,检查并清理冗余副本.实验结果表明：DSS能够提高数据响应率,降低响应时延,并保持较小的网络资源开销.     

基于定位信息的无线传感器网络IPv6地址配置方案*

提出了一种利用传感器节点定位信息实现无线传感器网络IPv6地址配置的方案.此方案根据定位信息将无线传感器网络划分为多个簇,簇首节点采用无状态策略为簇内节点分配IPv6地址.分析了此方案与Strong DAD及MANETConf的重复地址检测开销、地址配置总开销及地址配置总延迟时间等性能参数,分析结果验证了此方案的性能优于Strong DAD及MANETConf.     

An address configuration protocol for 6LoWPAN wireless sensor networks based on PDAD

In a wireless sensor network (WSN), data collected by a sensor node need to be associated with location information in order to support real-world applications. Taking the WSN characteristics into account, this paper proposes an address configuration scheme based on location information and passive duplicate address detection (PDAD). In this scheme, the network architecture based on location information is presented, and based on this architecture the address initialization algorithm and address maintenance algorithm are proposed. The address initialization algorithm is performed once the network starts, and it is made up of the initialization address configuration sub-algorithm (IAC) and the initialization location PDAD sub-algorithm (ILPDAD). The address maintenance algorithm is performed after the initialization algorithm is complete, and it is composed of the maintenance address configuration sub-algorithm (MAC) and the maintenance location PDAD sub-algorithm (MLPDAD). During the address initialization process (address maintenance process), a new node first uses IAC (MAC) to obtain an address and then performs ILPDAD (MLPDAD) to ensure the address uniqueness. Since beacon frames are employed to achieve IAC (MAC) and ILPDAD (MLPDAD), the address configuration cost and delay are reduced. Moreover, IAC (MAC) is based on location information and ILPDAD (MLPDAD) is based on PDAD, so there are always the sufficient address resources for address configuration without address reclamation. In this way, the extra cost and delay caused by both the address reclamation and the address configuration failure are avoided. This paper evaluates the performance of this scheme, and the data results show that this scheme effectively reduces the address configuration delay and cost.     

Formal firewall conformance testing: an application of test and proof techniques

Firewalls are an important means to secure critical ICT infrastructures. As configurable off‐the‐shelf products, the effectiveness of a firewall crucially depends on both the correctness of the implementation itself as well as the correct configuration. While testing the implementation can be done once by the manufacturer, the configuration needs to be tested for each application individually. This is particularly challenging as the configuration, implementing a firewall policy, is inherently complex, hard to understand, administrated by different stakeholders and thus difficult to validate. This paper presents a formal model of both stateless and stateful firewalls (packet filters), including NAT , to which a specification‐based conformance test case generation approach is applied. Furthermore, a verified optimisation technique for this approach is presented: starting from a formal model for stateless firewalls, a collection of semantics‐preserving policy transformation rules and an algorithm that optimizes the specification with respect of the number of test cases required for path coverage of the model are derived. We extend an existing approach that integrates verification and testing, that is, tests and proofs to support conformance testing of network policies. The presented approach is supported by a test framework that allows to test actual firewalls using the test cases generated on the basis of the formal model. Finally, a report on several larger case studies is presented. Copyright © 2014 John Wiley & Sons, Ltd.     

6LoWPAN无线传感器网络地址配置方案?

提出一种6LoWPAN无线传感器网络IPv6地址自动配置方案。将节点申请地址控制信息的传输范围控制在一跳范围内,无需记录地址分配状态与进行地址重复检测,以降低地址配置功耗,缩短地址配置时间。基于IPv6地址结构,给出节点失效时的地址回收算法。该方案从地址配置代价及地址配置延迟时间等方面与MANETConf方案、Strong DAD方案及LISAA方案的性能参数进行比较分析,结果验证了该方案的可行性和高效性。