A TDM slot allocation flow based on multipath routing in NoCs

Networks-on-chip have evolved as the natural solution for a scalable interconnect that can be automatically generated to suit the needs of the desired application. In this study we focus on improving the efficiency of on-chip networks using alternative routing strategies. We focus on a multi-path slot allocation method in networks with static resource reservations, in particular TDM NoCs. The simplicity of these networks makes it possible to implement this routing scheme without significant hardware overhead. Our proposed method, although displaying large variations between test cases, provides significant overall gains in terms of increased bandwidth or reduced working frequency or area. Our tests show that when using multipath routing the same communication requirements can be mapped on networks working on average at frequencies lower by 24.55% on average, while in individual cases the largest reduction was 60.04%. At the same time we are avoiding problems like deadlock and out-of-order delivery, commonly associated with multipath routing.     

一种对等网络分层管理资源定位模型

通过研究网络中小世界现象特征与数据流局部性特点,基于Kademlia协议设计了一种对等网络分层管理资源定位模型。模型通过重构Kademlia协议的网络拓扑结构,利用物理邻近节点访问优先的方法,来提高节点访问效率并优化节点的路由选择。仿真结果表明,设计的模型在继承了Kademlia模型优点的基础上,在节点路由选择和节点查找的平均逻辑路径长度等方面的性能均优于Kademlia模型。     

具有路由性能和蚁群优化的移动P2P路由策略*

目前的移动P2P网络路由策略不能较好适应网络拓扑结构的动态多变、网络和移动设备的资源有限等特点,以及不能较好解决路由建立和维护所带来的网络拥塞和资源消耗。针对上述问题,采用有限洪泛路由查询和移动agent路由查询相结合的策略,为每个移动节点提供丰富可靠、及时高效的路由信息。同时,使用改进的蚁群算法,综合考虑网络带宽、时延等多个路由性能指标,作为路由策略中路由选择机制。仿真研究证明,将所提出的理论与方法应用于移动P2P的路由选择和维护等问题,本算法在控制消息的开销、平均响应效率等方面具有良好的性能,对于网络     

网络功能虚拟化技术综述

无论是企业网还是数据中心,为实现相关应用功能、提升网络性能和加强网络安全等部署了大量的网络功能设备,但这些网络功能设备大多基于硬件,存在功能固化、扩展能力差、统一管理困难等问题。为解决上述问题,学术界和工业界不约而同将目光投向了网络功能虚拟化NFV技术。通过解耦网络功能和物理设备,使网络功能不受物理设备的约束,便于网络设备服务的升级更新,同时,NFV为新的体系结构、系统和应用的产生提供了可能。首先介绍了NFV技术,并与云计算和SDN进行对比,然后从VNF的系统结构、数据平面、控制平面、部署方式、实现语言和应用6个维度详细阐述了当前的研究成果,最后总结并展望了NFV未来的研究发展方向。     

CloudSimSDN-NFV: Modeling and simulation of network function virtualization and service function chaining in edge computing environments

Software-defined networking (SDN) has evolved and brought an innovative paradigm shift in computer networks by utilizing a programmable software controller with open protocols. Network functions, previously served on dedicated hardware, have shifted to network function virtualization (NFV) that enabled functions to be virtualized and provisioned dynamically upon generic hardware. In addition to NFV, edge computing utilizes the edge resources close to end-users, which can reduce the end-to-end service delay and the network traffic volume. Although these innovative technologies gained significant attention from both academia and industry, there are limited tools and simulation frameworks for the effectiveness evaluation in a repeatable and controllable manner. Furthermore, large-scale experimental infrastructures are expensive to setup and difficult to maintain. Even if they are created, they are not available or accessible for the majority of researchers throughout the world. In this paper, we propose a framework for simulating NFV functionalities in both edge and cloud computing environments. In addition to the basic network functionalities supported by SDN in CloudSimSDN, we added new NFV features, such as virtualized network functions allocation, migration, and autoscaling with the support of corresponding network functionalities, such as flow load balancing, rerouting, and service function chaining (SFC) maintenance. We evaluated our simulation framework with autoscaling and placement policies for SFC in the integrated edge and cloud computing environments. The results demonstrate its effectiveness in measuring and evaluating the end-to-end delay, response time, resource utilization, network traffic, and power consumption with different algorithms in each scenario.     

ADVS: a reputation-based model on filtering SPIT over P2P-VoIP networks

Interconnection among VoIP networks over the Internet is being an important trend. Therefore, distributed and self-organized VoIP networks are emerging as the times require. Because of VoIP’s cheapness and simplicity, many institutes forecast that it emerges as next spam entryway, like e-mail service. Especially, interconnected VoIP networks are self-organized and lack centralized authority. In this paper, we propose a novel scheme, called ADVS (Anti-Distributed Voice Spam), against SPIT (SPam over Internet Telephony) on the distributed and self-organized VoIP networks. ADVS presents a proper reputation model to evaluate end-user’s past behavior and accumulate other users’ referrals for detecting and filtering spam calls. In the VoIP network, ADVS acts as a middleware of VoIP proxy and constructs a DHT-based P2P network over call proxies and part of P2P-VoIP client to interlink each other and share end-user’s reputation. At the end of the paper, we verify AVDS through building simulation test bed. The results of experiment show that ADVS could detect spam calls accurately and stably.     

Dual partitioning multicasting for high-performance on-chip networks

As the number of cores integrated onto a single chip increases, power dissipation and network latency become ever-increasingly stringent. On-chip network provides an efficient and scalable interconnection paradigm for chip multiprocessors (CMPs), wherein one-to-many (multicast) communication is universal for such platforms. Without efficient multicasting support, traditional unicasting on-chip networks will be low efficiency in tackling such multicast communication. In this paper, we propose Dual Partitioning Multicasting (DPM) to reduce packet latency and balance network resource utilization. Specifically, DPM scheme adaptively makes routing decisions based on the network load-balance level as well as the link sharing patterns characterized by the distribution of the multicasting destinations. Extensive experimental results for synthetic traffic as well as real applications show that compared with the recently proposed RPM scheme, DPM significantly reduces the average packet latency and mitigates the network power consumption. More importantly, DPM is highly scalable for future on-chip networks with heavy traffic load and varieties of traffic patterns.     

A hybrid wavelet decomposer and GMDH-ELM ensemble model for Network function virtualization workload forecasting in cloud computing

Nowadays Network function virtualization (NFV) has drawn immense attention from many cloud providers because of its benefits. NFV enables networks to virtualize node functions such as firewalls, load balancers, and WAN accelerators, conventionally running on dedicated hardware, and instead implements them as virtual software components on standard servers, switches, and storages. In order to provide NFV resources and meet Service Level Agreement (SLA) conditions, minimize energy consumption and utilize physical resources efficiently, resource allocation in the cloud is an essential task. Since network traffic is changing rapidly, an optimized resource allocation strategy should consider resource auto-scaling property for NFV services. In order to scale cloud resources, we should forecast the NFV workload. Existing forecasting methods are providing poor results for highly volatile and fluctuating time series such as cloud workloads. Therefore, we propose a novel hybrid wavelet time series decomposer and GMDH-ELM ensemble method named Wavelet-GMDH-ELM (WGE) for NFV workload forecasting which predicts and ensembles workload in different time-frequency scales. We evaluate the WGE model with three real cloud workload traces to verify its prediction accuracy and compare it with state of the art methods. The results show the proposed method provides better average prediction accuracy. Especially it improves Mean Absolute Percentage Error (MAPE) at least 8% compared to the rival forecasting methods such as support vector regression (SVR) and Long short term memory (LSTM).     

网络功能虚拟化资源配置及优化研究综述

网络功能虚拟化(network functions virtualization,NFV)利用虚拟化技术将网络功能从专用硬件中分离形成虚拟网络功能,然后把虚拟网络功能映射到通用服务器、交换机或者存储器中,能有效地降低网络投资成本和运营成本,并提高网络服务部署的灵活性。网络功能虚拟化资源配置是实施NFV需要解决的一个关键问题。为深入剖析网络功能虚拟化资源配置,介绍了NFV的体系结构,重点阐述了资源配置的三个阶段及资源配置的优化,最后对高效资源配置面临的挑战和有价值的研究方向进行了思考,为NFV的研究提供参考。     

Performance evaluation of a mesh-evolving quality-of-service-aware multicast routing protocol for mobile ad hoc networks

The tremendous amount of multimedia applications running across the wireless communication medium makes quality of service (QoS) a fundamental requirement for mobile ad hoc networks. However, it is not easy to incorporate QoS into these networks. Moreover, the growing number of group-oriented applications also necessitates the efficient utilisation of network resources. The multicast model is a promising technique which can achieve this efficiency by facilitating the inherent broadcast capability of the wireless medium. The mesh-evolving ad hoc QoS multicast (MAQM) routing protocol is developed to address the resource efficiency and QoS problems with one, integrated solution. MAQM achieves multicast efficiency by tracking the availability of resources for each node within its neighbourhood. The QoS status is monitored continuously and announced periodically to the extent of QoS provision. Using these features, MAQM nodes can make their decisions on joining a new multicast session based on the sustainability of their perceived QoS. MAQM also evolves the initial multicast tree into a mesh during the course of an ongoing session to achieve a more robust network topology. Thus, MAQM integrates the concept of QoS-awareness into multicast routing in mobile ad hoc networks. Since ad hoc networks require the protocol control overhead to be as small as possible, we analyse the multicast session establishment process of MAQM to see its impact on the protocol performance in terms of system control overhead. We also evaluate the performance of MAQM through computer simulations using various qualitative and quantitative criteria. The simulation results validate our mathematical analysis of the control overhead and show that MAQM significantly improves multicast efficiency through its QoS-aware admission and routing decisions with an acceptably small overhead. Thus, MAQM shows that QoS is not only essential for, but also applicable to mobile ad hoc networks.     

WSN中层次型拓扑控制与网络资源配置联合设计方法

综合考虑异构无线传感器网络中节点速率分配、簇的划分规则和链路层网络频带资源占用情况, 提出一种基于拓扑控制与资源优化分配的层次型路由算法. 在网络层, 该算法根据成员节点和簇首节点的速率分配机制建立节点流量平衡模型. 在链路层, 分析无线传感器网络频谱共享行为, 研究邻近用户间访问冲突的规避抑制模型, 重构网络频带资源. 通过引入带宽比例因子将可用频带划分成若干子带, 提高网络频带资源的利用效率. 本文基于跨层联合设计思路, 建立一个混合整数非线性规划问题,对异构无线传感器网络中拓扑控制和网络资源分配问题联合设计, 得到最优的分簇结果和资源分配方案. 最后, 在设定网络拓扑中评估性能, 仿真结果证实该算法在网络频带资源充分利用的同时, 可实现最优的簇首匹配和路由建立结果.     

Management,control, and design of integrated networks with real-time dynamic routing

Integrated real-time dynamic routing (IRR) networks provide dynamic routing features for multiple classes-of-service on an integrated transport network. In this paper it is shown that IRR networks allow reduced network management costs since with real-time dynamic routing a number of network operations are simplified or eliminated. These simplifications include eliminating the storage of voluminous routing tables in the network switches, eliminating the calculation of routing tables in network design, simplifying the routing administration operations which require downloading new routing information to the network, and eliminating the automatic rerouting function in on-line traffic management. A new bandwidth allocation technique is described here which is based on the optimal solution of a network bandwidth allocation model for IRR networks. The model achieves significant improvement in both the average network blocking and node pair blocking distribution when the network is in a congested state such as under peak-day loads. In a paper to appear in the next Journal issue we further describe a new algorithm for the transport design of IRR networks which achieves near-optimal capacity engineering. These optimization techniques attain significant capital cost reductions and network performance improvements by properly modeling the more efficient operation of IRR networks.     

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.     

Intelligent shared-segment protection

Progress in network technologies and protocols is paving the road towards flexible optical transport networks, in which dynamic leasable circuits could be set up and released on a short-term basis according to customers’ requirements.Recently, new solutions for automatized network management promise to allow customers to specify the terms of the service level agreement (SLA) to be guaranteed (with different price range) by the service provider. In this paper we consider that these service level specifications (SLS), since they are now made available on-demand during the connection request, could be exploited to retrieve useful information able to improve the routing efficiency.In particular, we propose to exploit the knowledge of connection holding time, among the other SLS, to develop a novel intelligent approach for shared-segment protection (SSP).We will exploit the knowledge of the holding-time of connection requests to minimize resource overbuild due to backup capacity and hence to achieve resource-usage efficiency. For a typical US nationwide network, we compare our two proposed holding-time aware approaches to the respective two holding-time-unaware approaches: both of them, even in their holding-time unaware version, have been shown to be very efficient solutions for shared-segment protection. Nonetheless, we have obtained additional savings on resource overbuild of up to 11% for practical scenarios exploiting holding-time knowledge.     

基于Kademlia的P2P网络资源定位模型改进

根据基于分布式散列表(DHT)的P2P网络资源定位方法,将虚拟节点引入结构化P2P系统,在拓扑形成时充分利用网络访问的区域性和物理网络中节点的邻近性来降低访问延迟并优化路由选择。构建一种改进的基于Kademlia的P2P网络资源定位模型,提高了网络可扩展性和可管理性及网络运行效率和资源利用率。仿真结果表明,改进后的模型继承了DHT和Kademlia的优点,在路由选择、查找成功率和平均逻辑路径长度等方面的性能均优于原Kademlia模型。     

基于GEO/LEO卫星通信网的路由策略研究

从优化卫星网络管理的角度,提出了GEO/LEO卫星通信网络体系结构,该结构将管理子网与业务子网在物理上相互分离,体现了与地面网络不同的集中式路由策略的优势,同时利用卫星运行的规律性和星际链路分布的规则性,制定了极大降低运算量的备用路由策略,保证了GEO/LEO卫星网络体系结构的可靠性,通过仿真验证了两种路由策略的性能。     

End-to-End Security Across Wired-Wireless Networks for Mobile Users

ABSTRACT

Recent advances in mobile computing and wireless communication technologies are enabling high mobility and flexibility of anytime, anywhere service access for mobile users. As a result, network connections of such users often span over heterogeneous networking environments consisting of wired and wireless networking technologies. Both network heterogeneity and user mobility make the securing of data transmission over heterogeneous networks challenging and complex. In this paper, we focus on the challenge of providing secure end-to-end network transmissions to wireless mobile users. To minimize service interruption during ongoing secure sessions of mobile users, we present the design and implementation of an approach based on the well-known Internet Protocol Security (IPSec) standard. We conducted a performance evaluation of our implementation using a Voice over IP (VoIP) application over an actual network testbed. Our empirical performance results demonstrate a packet loss improvement of 17% to 34% (for various VoIP packet sizes) and a handoff delay improvement of almost 24% validating the high efficiency of our proposed approach.     

Optimizing NFV placement for distributing micro-data centers in cellular networks

With the popularity of mobile devices, the next generation of mobile networks has faced several challenges. Different applications have been emerged, with different requirements. Offering an infrastructure that meets different types of applications with specific requirements is one of these issues. In addition, due to user mobility, the traffic generated by the mobile devices in a specific location is not constant, making it difficult to reach the optimal resource allocation. In this context, network function virtualization (NFV) can be used to deploy the telecommunication stacks as virtual functions running on commodity hardware to meet users’ requirements such as performance and availability. However, the deployment of virtual functions can be a complex task. To select the best placement strategy that reduces the resource usage, at the same time keeps the performance and availability of network functions is a complex task, already proven to be an NP-hard problem. Therefore, in this paper, we formulate the NFV placement as a multi-objective problem, where the risk associated with the placement and energy consumption are taken into consideration. We propose the usage of two optimization algorithms, NSGA-II and GDE3, to solve this problem. These algorithms were taken into consideration because both work with multi-objective problems and present good performance. We consider a triathlon circuit scenario based on real data from the Ironman route as an use case to evaluate and compare the algorithms. The results show that GDE3 is able to attend both objectives (minimize failure and minimize energy consumption), while the NSGA-II prioritizes energy consumption.

     

A multi-path mechanism for reliable VoIP transmission over wireless networks

With the advances in audio encoding standards and wireless access networks, voice over IP (VoIP) is becoming quite popular. However, real-time voice data over lossy networks (such as WLAN and UMTS), still posses several challenging problems because of the adverse effects caused by complex network dynamics. One approach to provide QoS for VoIP applications over the wireless networks is to use multiple paths to deliver VoIP data destined for a particular receiver. This paper introduced cmpSCTP, a transport layer solution for concurrent multi-path transfer that modifies the standard stream control transmission protocol (SCTP). The cmpSCTP aims at exploiting SCTP’s multi-homing capability by selecting several best paths among multiple available network interfaces to improve data transfer rate to the same multi-homed device. Through the use of path monitoring and packet allotment techniques, cmpSCTP tries to transmit an amount of packets corresponding to the path’s ability. At the same time, cmpSCTP updates the transmission strategy based on the real-time information of all of paths. Using cmpSCTP’s flexible path management capability, we may switch the flow between multiple paths automatically to realize seamless path handover. The theoretical analysis evaluated the model of cmpSCTP and formulated optimal traffic fragmentation of VoIP data. Extensive simulations under different scenarios using OPNET verified that cmpSCTP can effectively enhance VoIP transmission efficiency and highlighted the superiority of cmpSCTP against the other SCTP’s extension implementations under performance indexes such as throughput, handover latency, packet delay, and packet loss.