Fuzzy Least-Congested Path Routing and Improved Remote-Path Routing based on Hierarchical Information in WDM Networks

Although routing schemes based on global knowledge make most optimal routing decisions, they will occupy many resources to keep the state information of the network up-to-date. In this work, we describe a fuzzy least-congested path (FLCP) routing algorithm based on hierarchical information. Simulation shows that the blocking probability using FLCP is very near to the blocking probability using the least-congested path routing (LCP) algorithm based on global information. Under heavy traffic load, the FLCP algorithm is superior to the exhaustive algorithm (EA) and the LCP algorithm with unit information cost. The FLCP algorithm provides better routing, even with incomplete information. Thus, the algorithm requires less information of the network, particularly under heavy traffic load. In addition, an improved remote-path routing approach is provided to reduce the blocking probability of connection requests to a node that is many hops away from the source node.     

Layer-preference policies in multi-layer GMPLS networks

We address the problem of routing Label Switched Paths (LSPs) in multi-layer networks based on the Generalized MultiProtocol Label Switching (GMPLS) paradigm. In particular, we pursue policies for choosing the appropriate layer to host a new LSP request, as we find that such layer-preference policies have significant impact on network performance. We discuss several simple layer-preference policies and we reveal why these simple policies ruin network performance in the long run. Consequently, we develop an efficient heuristics, the Min-phys-hop routing and wavelength assignment algorithm, to govern the selection of the best layer of a multi-layer network in which to host new LSP requests. We discuss the applicability of this algorithm with respect to the state-of-the-art GMPLS standards, above all, the GMPLS routing extensions to OSPF-TE. By extensive simulations, we justify that the Min-phys-hop algorithm produces close-to-optimal blocking and resource consumption under almost all possible selections of input parameters, and this is regardless of the wavelength and Optical-Electrical-Optical (OEO) conversion capability present in the network.     

Dynamic Routing in WDM Grooming Networks

Traffic grooming in optical networks has gained significant importance in recent years due to the prevailing sub-wavelength traffic requirement of end-users. In this paper, a methodology for dynamic routing of fractional-wavelength traffic in WDM grooming networks is developed. To evaluate the performance of routing algorithms, a new performance metric that reflects the network utilization is also proposed. The performances of shortest-widest path, widest-shortest path, and available shortest path routing algorithms are evaluated on a class of WDM grooming networks by considering traffic of different capacity requirements. The effect of dispersity routing, where higher capacity requests are broken into multiple unit capacity requests, is also investigated. The most interesting counter-intuitive result that is observed is that increasing the grooming capability in a network could result in degrading the performance of the widest-shortest path algorithm.     

A novel robust routing algorithm for multi-granularity connection requests in wavelength division multiplexing mesh networks

In this paper, we propose a novel robust routing algorithm based on Valiant load-balancing under the model of polyhedral uncertainty (i.e., hose uncertainty model) for WDM (wavelength division multiplexing) mesh networks. Valiant load-balanced robust routing algorithm constructs the stable virtual topology on which any traffic patterns under the hose uncertainty model can be efficiently routed. Considering there are multi-granularity connection requests in WDM mesh networks, we propose the method called hose-model separation to solve the problem for the proposed algorithm. Our goal is to minimize total network cost when constructing the stable virtual topology that assures robust routing for the hose model in WDM mesh networks. A mathematical formulation (integer linear programming, ILP) about Valiant load-balanced robust routing algorithm is presented. Two fast heuristic approaches are also proposed and evaluated. We compare the network throughput of the virtual topology constructed by the proposed algorithm with that of the traditional traffic grooming algorithm under the same total network cost by computer simulation.     

Split agent‐based routing in interconnected networks

Adaptive behaviour of swarm‐based agents (BT Technol. J. 1994; 12 :104–113; AAMAS Conference '02, Melbourne, Australia, Month 1–2, 2002; Softcomput. J. 2001; 5 (4):313–317.) is being studied in this paper with respect to network throughput for a certain amount of data traffic. Algorithmically complex problems like routing data packets in a network need to be faced with a dynamically adaptive approach such as agent‐based scheme. Particularly in interconnected networks where multiple networks are participating in order to figure a large‐scale network with different QoS levels and heterogeneity in the service of delay sensitive packets, routing algorithm must adopt in frequent network changes to anticipate such situations. Split agent‐based routing technique (SART) is a variant of swarm‐based routing (Adapt. Behav. 1997; 5 :169–207; Proceedings of 2003 International Symposium on Performance Evaluation of Computer and Telecommunication Systems—SPECTS, Montreal, Canada, July 20–24, 2003; 240–247.) where agents are split after their departure to the next node on a hop‐by‐hop basis. Packets that are delay sensitive are marked as prioritized which agents recognize‐as being a part of a packet‐ and try to influence the two‐way routing tables. Thorough examination is made, for the performance of the proposed algorithm in the network and the QoS offered, taking into account a number of metrics. It is shown that the split agent routing scheme applied to interconnected networks offers a decentralized control in the network and an efficient way to increase overall performance and packet control reducing at the same time the packet loss concept. Copyright © 2004 John Wiley & Sons, Ltd.     

基于梯度加速算法的LSP流量分配算法

本文在MPLS系统模型中提出了一种基于加速梯度算法的LSP流量分配算法。仿真结果表明,它可以减少由传统路由算法引起的网络拥塞和包丢失率;随着LSP请求数的增加减少了LSP的拒绝数,优化网络资源的利用率,降低了资源占用率,提高了系统的稳定性。     

Performance of split routing algorithm for three-stage multicastnetworks

This paper studies three-stage Clos (1953) switching networks for multicast communications in terms of their blocking probabilities on a random traffic model. Even though the lack of multicast capability in input-stage switches requires a prohibitively large number of middle switches to provide compatible requests with nonblocking paths, the probabilistic model gives an observation that the blocking probability decreases drastically and then approaches zero as the number of middle switches is far less than the theoretical bound. The S-shaped curves of blocking probability versus degree of fanout indicate that high fanout requests are mostly blocked at some given reference network utilization. A split routing algorithm and its blocking probability are introduced to enhance the routability of the high fanout requests. We also corroborate the analytic model by performing network simulations based on a random request generator and a random routing strategy     

WDM 网络中基于优先级的多任务波长路由分配算法

提出了一种在WDM网络中基于优先级的多任务波长路由分配算法。算法设计旨在提高光网络资源的利用率、降低网络请求阻塞率。分析了任务请求的路由类型以及负载容量对请求优先级划分的影响方式,给出了网络请求优先级划分策略,结合网络的实时状态提出了一种基于优先级的多任务波长路由分配算法。仿真结果表明,该算法相比现有算法降低了网络请求阻塞率,提高了资源利用率。     

多拓扑路由在小卫星网络中的容错保护与流量优化

小卫星星座网络需要具有很好的容错抗毁能力,同时对于不同业务流能选择不同的优化路径进行传输。提出使用多拓扑路由技术解决小卫星星座网络的网络保护和流量优化传输问题。在STK和OPNET平台上设计了小卫星星座网络模型和多拓扑路由协议,并进行了仿真实验。仿真结果验证了星座网络的容错保护功能和对不同业务流的多路径路由选择功能。     

Online multicast routing with bandwidth guarantees: a new approach using multicast network flow

We present a new algorithm for online routing of bandwidth-guaranteed multicasts where routing requests arrive one by one without any prior knowledge of future requests. A multicast routing request consists of a source, a set of receivers, and a bandwidth requirement. Two multicast applications of interest are routing of point-to-multipoint label-switched paths in multiprotocol label switched (MPLS) networks, and the provision of bandwidth-guaranteed virtual private network (VPN) services under the "hose" service model. Without prior knowledge of multicast requests, offline multicast routing algorithms cannot be used. Online algorithms are needed to handle requests arriving one by one and to satisfy as many potential future demands as possible. Our new online algorithm is based on the idea that a newly routed multicast must follow a route that does not interfere too much with network paths that may be critical to satisfy future demands. We develop a multicast tree selection heuristic based on the idea of deferred loading of certain critical links. The algorithm identifies them as links that, if heavily loaded, would make it impossible to satisfy future demands between certain ingress-egress pairs. The algorithm uses link-state information and some auxiliary capacity information for multicast tree selection and is amenable to distributed implementation. Unlike previous algorithms, our algorithm exploits any available knowledge of the network ingress-egress points of potential future demands, even though the demands themselves are unknown. It performs very well.     

Diverse Path Routing with Interference and Reusability Consideration in Wireless Mesh Networks

Multipath routing has been extensively employed in wireless mesh networks (WMNs) for providing network reliability and survivability, therefore, improves energy consumptions. To provide network survivability, each user should be protected against failures, either node or link failures. For each request, a primary path is set up for normal transmission, and an alternate path (protection path) should also be provided to protect the request in case of network failure. In this paper, we study how to provide survivability using multi-path scheme for dynamic network traffic, where users’ requests have random arrival times. Compared with previous work, our scheme considers interference and reusability factors when providing multiple paths for each request. By applying our scheme, the numerical results show that we can accommodate about 17% more requests than previous schemes. Meanwhile, the results show that our scheme not only accommodates more requests, but also takes less running time to find a solution for each request.     

A Bandwidth Guaranteed Integrated Routing Algorithm in IP over WDM Optical Networks

In this paper, we have developed an integrated online algorithm for dynamic routing of bandwidth guaranteed label switched paths (LSPs) in IP-over-WDM optical networks. Traditionally, routing at an upper layer (e.g., IP layer) is independent of wavelength routing at the optical layer. Wavelength routing at the optical layer sets up a quasi-static logical topology which is then used at the IP layer for IP routing. The coarse-grain wavelength channels and the pre-determined virtual topologies with respect to some a priori assumed traffic distribution are barriers to efficient resource use and inflexible to changing traffic. We take into account the combined knowledge of resource and topology information at both IP and optical layers. With this added knowledge, an integrated routing approach may extract better network efficiencies, be more robust to changing traffic patterns at the IP layer than schemes that either use dynamic routing information at the IP layer or use a static wavelength topology only. LSP set-up requests are represented in terms of a pair of ingress and egress routers as well as its bandwidth requirement, and arrive one-by-one. There is no a priori knowledge regarding the arrivals and characteristics of future LSP set-up requests. Our proposed algorithm considers not only the importance of critical links, but also their relative importance to routing potential future LSP set-up requests by characterizing their normalized bandwidth contribution to routing future LSP requests with bandwidth requirements. Moreover, link residual bandwidth information that captures the link's capability of routing future LSPs is also incorporated into route calculation. Extensive simulation was conducted to study the performance of our proposed algorithm and to compare it with some existing ones, such as the integrated minimum hop routing algorithm and the maximum open capacity routing algorithm. Simulation results show that our proposed algorithm performs better than both routing algorithms in terms of the number of LSP set-up requests rejected and the total available bandwidth between router pairs.     

自动交换光网络中恢复路径提供机制的研究

为了获得高效的网络生存性能,基于自动交换光网络(ASON)的框架,该文提出了一种新型的可恢复路径选择算法-联合可变权重可恢复路径(JVWR)选择算法,并进行了数值仿真分析,仿真结果表明,此恢复路径选择算法具有明显的业务量均衡能力,并降低了动态连接请求的阻塞概率,同时具有良好的带宽利用率和恢复资源共享效率。该文还对mesh网络业务路径和恢复路径的建立机制进行了讨论,在ASON功能框架之内,基于通用多协议标记交换提出了并行mesh共享恢复路径建立机制,从而较系统地对分布式恢复路径动态建立机制进行了研究。     

RATES: a server for MPLS traffic engineering

It has been suggested that one of the most significant reasons for multiprotocol label switching (MPLS) network deployment is network traffic engineering. The goal of traffic engineering is to make the best use of the network infrastructure, and this is facilitates by the explicit routing feature of MPLS, which allows many of the shortcomings associated with current IP routing schemes to be addressed. This article describes a software system called Routing and Traffic Engineering Server (RATES) developed for MPLS traffic engineering. It also describes some new routing ideas incorporated in RATES for MPLS explicit path selection. The RATES implementation consists of a policy and flow database, a browser-based interface for policy definition and entering resource provisioning requests, and a Common Open Policy Service protocol server-client implementation for communicating paths and resource information to edge routers. RATES also uses the OSPF topology database for dynamically obtaining link state information. RATES can set up bandwidth-guaranteed label-switched (LSPs) between specified ingress-egress pairs. The path selection for LSPs is on a new minimum-interference routing algorithm aimed at making the best use of network infrastructure in an online environment where LSP requests arrive one by one with no a priori information about future requests. Although developed for an MPLS application, the RATES implementation has many similarities in components to an intradomain differentiated services bandwidth broker     

On the effectiveness of alternative paths in QoS routing

We propose a routing strategy in which connection requests with specific bandwidth demands can be assigned to one of several alternative paths connecting the source to the destination. The primary goal of this multiple‐path approach is to compensate for the inaccuracy of the knowledge available to routing nodes, caused by the limited frequency of link state (LS) information exchanges. We introduce a collection of K‐shortest path routing schemes and investigate their performance under a variety of traffic conditions and network configurations. We subsequently demonstrate that K‐shortest path routing offers a lower blocking probability in all scenarios and more balanced link utilization than other routing methods discussed in the literature. With our approach, it is possible to reduce the frequency of link state exchanges, and the incurred bandwidth overhead, without compromising the overall performance of the network. Based on the proposed routing scheme, we investigate different link state dissemination algorithms, which are aimed at reducing the communication overhead by prioritizing the scope and differentiating the qualitative content of LS update messages. Copyright © 2004 John Wiley & Sons, Ltd.     

Resource optimization algorithm of combination of NFV and SDN for application of multiple services

Various services of internet of things (IoT) require flexible network deployment to guarantee different quality of service (QoS).Aiming at the problem of IoT service function chain deployment,network function virtualization (NFV) and software defined networking (SDN) were combined to optimize resources.Considering forwarding cost and traffic load balance,a joint optimization model of virtual network function placement and service function chain routing was given and was proved to be NP-Hard.In order to solve this model,two heuristic algorithms were proposed.One was the service chain deployment algorithm of first routing then placing (FRTP) and the other was the placing followed by routing (PFBR) based on node priority.Simulation results demonstrate that FRTP and PFBR algorithm can significantly balance network traffic load while alleviating congestion and improving the acceptance ratio of the chain requests compared with other algorithms.     

E‐TDGO: An encrypted trust‐based dolphin glowworm optimization for secure routing in mobile ad hoc network

Mobile ad hoc networks (MANETs) are independent networks, where mobile nodes communicate with other nodes through wireless links by multihop transmission. Security is still an issue to be fixed in MANETs. Hence, a routing protocol named encrypted trust‐based dolphin glowworm optimization (DGO) (E‐TDGO) is designed using Advanced Encryption Standard‐128 (AES‐128) and trust‐based optimization model for secure routing in MANET. The proposed E‐TDGO protocol includes three phases, namely, k‐path discovery, optimal path selection, and communication. At first, k paths are discovered based on the distance and the trust level of the nodes. From the k paths discovered, the optimal path is selected using a novel algorithm, DGO, which is developed by combining glowworm swarm optimization (GSO) algorithm and dolphin echolocation algorithm (DEA). Once the optimal path is selected, communication begins in the network such that E‐TDGO protocol ensures security. The routing messages are encrypted using AES‐128 with shared code and key to offer security. The experimental results show that the proposed E‐TDGO could attain throughput of 0.11, delay of 0.01 second, packet drop of 0.44, and detection rate of 0.99, at the maximum number of rounds considered in the network of 75 nodes with attack consideration.     

MPLS网络中保证服务质量的多径路由选择策略

本文提出了一种在多协议标签交换(MPLS, Multiple Protocol Label Switching) 网络中保证服务质量 (QoS,Quality-of-Service) 的多径路由选择策略,其核心思想是引入多路径分散业务量机制,在保证用户服务质量要求的同时达到增加网络呼叫接受率和平衡网络负载的目的.文中着重讨论了用户端对端服务质量要求的多路分解和分配问题,在此基础上提出了多径路由的分支路径选择策略,并研究了策略中的关键参数K对该策略性能的影响.数值结果显示出多路径分散业务量在网络负载均衡方面的重要意义,并且表明用户的要求相对网络资源越高使用多径传输的优势越明显.     

Design of OSPF networks using subpath consistent routing patterns

We address the problem of designing IP networks where the traffic is routed using the OSPF protocol. Routers in OSPF networks use link weights set by an administrator for determining how to route the traffic. The routers use all shortest paths when traffic is routed to a destination, and the traffic is evenly balanced by the routers when several paths are equally short. We present a new model for the OSPF network design problem. The model is based on routing patterns and does not explicitly include OSPF weights. The OSPF protocol is modeled by ensuring that all pairs of routing patterns are subpath consistent, which is a necessary condition for the existence of weights. A Lagrangean heuristic is proposed as solution method, and feasible solutions to the problem are generated using a tabu search method. Computational results are reported for random instances and for real-life instances.     

SRNoC: A novel high performance Shared-Resource routing scheme for Network-on-Chip

This paper proposes a novel Shared-Resource routing scheme, SRNoC, that not only enhances network transmission performance, but also provides a high efficient load-balance solution for NoC design. The proposed SRNoC scheme expands the NoC design space and provides a novel effective NoC framework. SRNoC scheme mainly consists of the topology and routing algorithm. The proposed topology of SRNoC is based on the Shared-Resource mechanism, in which the routers are divided into groups and each group of routers share a set of specified link resource. Because of the usage of Shared Resource mechanism, SRNoC could effectively distribute the workload uniformly onto the network so as to improve the utilization of the resource and alleviate the network congestion. The proposed routing algorithm is a minimal oblivious routing algorithm. It could improve average latency and saturation load owing to its flexibility and high efficiency. In order to evaluate the load-balance property of the network, we proposed a method to calculate the Φ which represents the characteristic value of load-balance. The smaller the Φ, the better the performance in load-balance. Simulation results show that the average latency and saturation load are dramatically improved by SRNoC both in synthetic traffic patterns and real application traffic trace with negligible hardware overhead. Under the same simulation condition, SRNoC could cut down the total network workload to 48.67% at least. Moreover, SRNoC reduces the value of Φ 45% at least compared with other routing algorithms, which means it achieves better load-balance feature.