Surveillance strategies for a class of adaptive-routing algorithmsin circuit-switched DNHR communications networks: a simulationstudy

A large, circuit-switched, communications network engineered for historical traffic patterns using dynamic nonhierarchical routing (DNHR) is considered. During overloads, the offered traffic many not follow the historical patterns. In such situations, it is possible to increase network throughput by augmenting the routing tables in near-realtime to utilize instantaneous spare capacity. The surveillance strategy determines how often network data is collected and how frequently additional paths are added to the routing tables. Six surveillance strategies for adaptive routing are examined: (1) 2.5-min surveillance interval; (2) 5-min surveillance interval; (3) 10-min surveillance interval; (4) 15-min surveillance interval; (5) modify the routing every other 5 min; and (6) modify the routing every 5 min with a fixed 10-min lag before the routing tables are changed. Simulation is used to compare the network performance to the baseline performance without adaptive routing for each of the strategies. It is found that the more adaptive strategies, (1), (2), and (6), perform better during periods with variable traffic, and that the less adaptive strategies perform better during periods with stable traffic. During heavy overloads, almost as important as the surveillance strategy is the number of problems, overflowing node pairs, and the algorithm attempts to relieve     

一种无线传感器网路由算法的设计与实现

讨论了无线传感器网络的特殊性,分析了其路由算法的需求。借鉴Ad Hoc网中比较成熟的AODV(Ad Hoc按需平面距离矢量)协议和DSR(动态源路由)协议,采用了按需驱动的路由策略,优化了路由建立和维护算法,提出了RODR(简化的按需路由)协议。采用该路由算法的网络协议已在由ATmega128L微处理器和CC2420构成的节点机上实现,通过组网实验,初步验证了其可行性。     

Adaptive proportional routing: a localized QoS routing approach

Most of the QoS routing schemes proposed so far require periodic exchange of QoS state information among routers, imposing both communication overhead on the network and processing overhead on core routers. Furthermore, stale QoS state information causes the performance of these QoS routing schemes to degrade drastically. In order to circumvent these problems, we focus on localized QoS routing schemes where the edge routers make routing decisions using only local information and thus reducing the overhead at core routers. We first describe virtual capacity based routing (vcr), a theoretical scheme based on the notion of virtual capacity of a route. We then propose proportional sticky routing, an easily realizable approximation of vcr and analyze its performance. We demonstrate through extensive simulations that adaptive proportional routing is indeed a viable alternative to the global QoS routing approach.     

NHRPA: a novel hierarchical routing protocol algorithm for wireless sensor networks

Considering severe resources constraints and security threat hierarchical routing protocol algorithm. The proposed routing of wireless sensor networks （WSN）, the article proposed a novel protocol algorithm can adopt suitable routing technology for the nodes according to the distance of nodes to the base station, density of nodes distribution, and residual energy of nodes. Comparing the proposed routing protocol algorithm with simple direction diffusion routing technology, cluster-based routing mechanisms, and simple hierarchical routing protocol algorithm through comprehensive analysis and simulation in terms of the energy usage, packet latency, and security in the presence of node protocol algorithm is more efficient for wireless sensor networks. compromise attacks, the results show that the proposed routing     

SDI: a multi-domain SDN mechanism for fine-grained inter-domain routing

Software-defined networking (SDN) scheme decouples network control plane and data plane, which can improve the flexibility of traffic management in networks. OpenFlow is a promising implementation instance of SDN scheme and has been applied to enterprise networks and data center networks in practice. However, it has less effort to spread SDN control scheme over the Internet to conquer the ossification of inter-domain routing. In this paper, we further innovate to the SDN inter-domain routing inspired by the OpenFlow protocol. We apply SDN flow-based routing control to inter-domain routing and propose a fine-granularity inter-domain routing mechanism, named SDI (Software Defined Inter-domain routing). It enables inter-domain routing to support the flexible routing policy by matching multiple fields of IP packet header. We also propose a method to reduce redundant flow entries for inter-domain settings. And, we implement a prototype and deploy it on a multi-domain testbed.     

Routing techniques in wireless sensor networks: a survey

Wireless sensor networks consist of small nodes with sensing, computation, and wireless communications capabilities. Many routing, power management, and data dissemination protocols have been specifically designed for WSNs where energy awareness is an essential design issue. Routing protocols in WSNs might differ depending on the application and network architecture. In this article we present a survey of state-of-the-art routing techniques in WSNs. We first outline the design challenges for routing protocols in WSNs followed by a comprehensive survey of routing techniques. Overall, the routing techniques are classified into three categories based on the underlying network structure: flit, hierarchical, and location-based routing. Furthermore, these protocols can be classified into multipath-based, query-based, negotiation-based, QoS-based, and coherent-based depending on the protocol operation. We study the design trade-offs between energy and communication overhead savings in every routing paradigm. We also highlight the advantages and performance issues of each routing technique. The article concludes with possible future research areas.     

分布式认知无线电网络多路径路由协议研究综述

为了深入研究分布式认知无线电网络的多路径路由问题,阐述了分布式认知无线电网络基本特征以及多路径路由设计面临的问题与挑战。分布式认知无线电网络多路径路由采用多路径并行传输,可有效降低传输时延、增加网络吞吐量与传输可靠性、实现网络负载均衡。根据路由优化目标不同,从吞吐量、带宽、干扰、时延、负载均衡和路由发现六方面对近年来多路径路由协议的主要研究成果进行了分类,然后逐类对多路径路由协议进行了分析和讨论,最后分别从分布式认知无线电网络基本特征的适应性与多路径路由协议特征两个方面进行了比较,并展望了分布式认知无线电网络多路径路由协议需进一步研究的方向。     

Buffered fixed routing: a routing protocol for real-time transportin grid networks

We propose a new routing protocol called buffered fixed routing (BFR) for real-time applications on grid networks. While previous routing protocols for grid networks have been designed to improve network throughput, the BFR scheme is proposed to guarantee the end-to-end packet delay and sequencing without loss by using finite buffers at each node. Thus the proposed scheme can satisfy quality-of-service (QoS) requirements of real-time applications. The BFR scheme uses the token on the row ring to provide QoS guarantees. The performance of the BFR scheme is analyzed by using the Geom/Geom/1 queueing system under uniform traffic. In the simulation, the BFR scheme shows the zero-loss, high-throughput performance with the minimum delay variation compared to other routing protocols such as store and forward routing, deflection routing and vertical routing. In addition, it has shown the smallest average delay at intermediate and heavy loads     

Recursive Algorithms for Computing End-to-End Blocking in a Network with Arbitrary Routing Plan

This paper presents three recursive algorithms for computing end-to-end blocking probabilities in a network with alternate routing, based on link blocking probabilities. The only assumption made is the statistical independence of link blocking probabilities. The first algorithm applies to arbitrary routing plans. The second algorithm applies to single-loss-route routing plans which include predictive routing plans used in advanced private networks. The second algorithm is also applicable to solving the terminal-pair reliability problem. The third algorithm applies to tandem-node-matrix-generated routing plans which include hierarchical routing plans similar to those used in North American public toll network, AT&T's CCSA, EPSCS, and ETN networks. These three algorithms are progressively more efficient.     

Intradomain QoS routing in IP networks: a feasibility andcost/benefit analysis

Constraint-based routing gradually becomes an essential enabling mechanism for a variety of emerging network services such as virtual private networking and QoS support. A number of previous works have recognized its significance and investigated many aspects of the operation of constraint-based routing and in particular its variant concerned with determining paths for requests with specific QoS requirements, known as QoS routing. In this work we build on previous results on the cost of QoS routing and investigate the performance/cost trade-offs involved in the operation of a representative QoS routing architecture, elaborate on the constituents of this cost, and identify the main methods for containing the cost that QoS routing incurs on routers. Our results show that the cost of QoS routing is not excessive and that there indeed exist operational configurations, which can achieve reasonable performance gains with only a minimal increase in processing cost when compared to conventional best-effort routing     

Routing in ad hoc networks: a case for long hops

For multihop wireless networks, a fundamental question is whether it is advantageous to route over many short hops (short-hop routing) or over a smaller number of longer hops (long-hop routing). Short-hop routing has gained a lot of support, and its proponents mainly produce two arguments: reduced energy consumption and higher signal-to-interference ratios. Both arguments stem from a simplified analysis based on crude channel models that neglects delay, end-to-end reliability, bias power consumption, the impact of channel coding, mobility, and routing overhead. In this article we shed more light on these issues by listing 18 reasons why short-hop routing is not as beneficial as it seems to be. We also provide experimental evidence to support this claim. The conclusion is that for many networks, long-hop routing is in every aspect a very competitive strategy.     

Integrating bridges and routers in a large internetwork

A review is presented of the principal functional characteristics of routers and bridges, particularly as they relate to the construction of large-scale internetworks. The discussion of bridges covers filtering performance, forwarding performance, packet latency, adaptability, internetwork topology, network management, security transparency, and multiway and fault-tolerant bridges. The discussion of routers covers network layer protocols, internetwork size, static versus dynamic routing, routing information updates, network management, routing optimizations, session survivability, contamination containment, routing optimization, and load sharing     

Multihop lightwave networks: a comparison of store-and-forward andhot-potato routing

The achievable aggregate capacity for a variant of the basic multihop approach in which minimum distance store-and-forward routing is replaced by a hot-potato routing algorithm is determined. With hot-potato routing, all packets simultaneously arriving at a given node and not intended for reception at that node are immediately placed onto the outbound links leaving that node; if two or more packets contend for the same outgoing link to achieve a minimum distance routing, then all but one will be misrouted to links which produce longer paths to the eventual destination. Attention is confined to the development of an analytical methodology for finding the probability distribution of the number of hops with hot potato routing for symmetric networks under uniform traffic load. Results show that the maximum throughput achievable with hot-potato routing can be as low as 25% of that for store-and-forward routing, and that the relative degradation increases as the number of nodes grows larger. This implies that the link speed up needed to produce a significant overall capacity advantage with hot potato should be at least a factor of 10     

CEDAR: a core-extraction distributed ad hoc routing algorithm

We present CEDAR, a core-extraction distributed ad hoc routing algorithm for quality-of-service (QoS) routing in ad hoc network environments, CEDAR has three key components: (a) the establishment and maintenance of a self-organizing routing infrastructure called the core for performing route computations; (b) the propagation of the link-state of high bandwidth and stable links in the core through increase/decrease waves; and (c) a QoS-route computation algorithm that is executed at the core nodes using only locally available state. The performance evaluations show that CEDAR is a robust and adaptive QoS routing algorithm that reacts quickly and effectively to the dynamics of the network while still approximating the performance of link-state routing for stable networks     

Diversity reception in a multihop packet radio network

The performance improvement which results from the use of multiple antennas at each node in a multihop packet radio network is examined. Four transmission strategies based on three previously proposed routing schemes and one new routing scheme, MTP, are studied. It is found that the use of two antennas can improve the performance of all four transmission strategies by about 25% in a Rayleigh fading environment. The transmission strategy based on the MTP routing scheme is shown to be generally superior to those based on the other three routing schemes. This revised version was published online in June 2006 with corrections to the Cover Date.     

因特网路由协议研究综述

路由器是因特网组网的关键设备，而路由器的主要功能是运行路由协议，并与其它路由器交换路由信息形成本机上的路由表，同时根据路由表的信息正确转发分组。在Internet中，路由协议至关重要，它直接影响网络的性能。近年来，路由协议领域中开展了大量的研究工作，有力地推动了Internet的发展。本总结了当今Internet上所使用的单播、组播、QoSR、移动等路由协议的研究现状，并分析了进一步的研究方向。     

General gate array routing using a k-terminal net routing algorithmwith failure prediction

A general approach to gate array routing based on an abstract routing space model is presented. An efficient k-terminal net maze runner is described. It does not partition nets into two-terminal net routing problems, but solves the problem by simultaneously growing k search waves. It is shown that the explored routing space diminishes when compared to bidirectional routing schemes. Experimental data show a reduction of CPU time up to 55% and a decrease of total net length up to 6% compared to a bidirectional maze router. For k-terminal nets it is shown that net length decreases with increasing k. Additional routing space restriction is attained by use of variable search space restriction and by the introduction of a dynamic routing space partitioning method based on the concept of regions. This concept allows for determination of nonroutable nets or parts of nets in an efficient way. The new partitioning method may be implemented in any maze runner without increasing the complexity of the maze runner algorithm. Results show an additional decrease of CPU time up to 35%     

Diversity reception in a multihop packet radio network

The performance improvement which results from the use of multiple antennas at each node in a multihop packet radio network is examined. Four transmission strategies based on three previously proposed routing schemes and one new routing scheme, MTP, are studied. It is found that the use of two antennas can improve the performance of all four transmission strategies by about 25% in a Rayleigh fading environment. The transmission strategy based on the MTP routing scheme is shown to be generally superior to those based on the other three routing schemes. This revised version was published online in June 2006 with corrections to the Cover Date.     

Computing approximate blocking probabilities for a class ofall-optical networks

We study a class of all-optical networks using wavelength-division multiplexing (WDM) and wavelength routing, in which a connection between a pair of nodes in the network is assigned a path and a wavelength on that path. Moreover, on the links of that path no other connection can share the assigned wavelength. Using a generalized reduced load approximation scheme we calculate the blocking probabilities for the optical network model for two routing schemes: fixed routing and least loaded routing     

延迟优化的统一可编程互连电路设计和实现

本文设计了一种对可编程逻辑单元CLB和可编程输出单元IOB均具有统一结构的可编程互连电路。通过偏移互连线和回线技术,使得同种可编程互连线的负载分布均匀,保证了可编程逻辑器件FPGA芯片中信号传输的可预测性和规整性;同时,设计过程中对编程点和驱动器电路进行专门的优化设计,减少了5%延时。运用该互连电路到实例FPGA芯片--FDP芯片中,流片后实测数据表明：该可编程互连电路中各种互连线功能正确,可以正确地完成各种信号的互连,整个芯片的延迟统一而且可预测。