A Hybrid End-to-End QoS Path Computation Algorithm for PCE-Based Multi-Domain Networks

Inter-domain quality of service (QoS) routing is a challenging problem for today’s Internet. This problem requires the computation of paths that cross multiple domains and meet different QoS constraints. In addition, the used computation methods must meet the constraints of confidentiality and autonomy imposed by the domains of different operators. Path computation element (PCE)-based architecture offers a promising solution for inter-domain QoS routing. It ensures the computation of end-to-end QoS paths while preserving the confidentiality and the autonomy of the domains. In this paper, we propose a novel hybrid end-to-end QoS path computation algorithm, named HID-MCP, for PCE-based networks. HID-MCP is a hybrid algorithm that combines the advantages of pre-computation and on-demand computation to obtain end-to-end QoS paths. Moreover, it integrates a crankback mechanism for improving path computation results in a single domain or in multiple domains based on the PCE architecture. Detailed analyses are provided to assess the performance of our algorithm in terms of success rate and computational complexity. The simulation results show that our algorithm has an acceptance rate of the requests very close to the optimal solution; precisely, the difference is lower than 1 % in a realistic network. Moreover, HID-MCP has a low computational complexity. Besides, our solution relies on the PCE architecture to overcome the limitations related to inter-domain routing such as domain autonomy and confidentiality.     

Distributed inter-domain lightpath provisioning in the presence of wavelength conversion

Dense wavelength division multiplexing (DWDM) has become the dominant transport layer technology for next-generation backbone networks due to its unprecedented capacity scalability. As a result, there is a pressing need to investigate lightpath provisioning in multi-domain DWDM networks. Although inter-domain provisioning has been well-studied for packet/cell-switching networks, the wavelength dimension (along with wavelength conversion) presents many added challenges. To address these concerns, a detailed GMPLS-based hierarchical routing framework for provisioning transparent/translucent/opaque multi-domain DWDM networks is presented. The scheme adapts topology abstraction to hide internal domain state so as to resolve routing scalability and security issues. Specifically a novel full-mesh topology abstraction scheme is developed for full wavelength conversion domains, i.e., to disseminate additional wavelength converter state. Related inter-domain lightpath RWA and signaling schemes are also tabled. Performance analysis results are then presented to demonstrate the effectiveness of the proposed mechanisms along with directions for future research work.     

Local segment-shared protection based on source egress gateway selection for multi-domain optical mesh networks

Survivability for multi-domain optical networks is becoming a key parameter due to expanding network. In order to provide the shared-path-protected lightpath in multi-domain optical mesh networks, we propose a protection solution, called GSLSSP. A new source egress gateway selecting mechanism is adopted in this solution. For each connection request, this mechanism can enable the source node to select a better egress gateway node to the destination domain and compute one inter-domain working path n...     

多域光网络中应用混合拓扑聚合的分段保护算法

研究了多域光网络中的路由保护问题;为了克服多域光网络中可扩展性约束,提出了一种混合拓扑聚合方法。该方法结合了全连通和生成树拓扑聚合的优点,在网络中需要存储和发布的链路状态信息与聚合信息反映实际物理拓扑的精确性之间进行了折中;然后在此混合拓扑聚合方法的基础上,提出了一种基于查询机制的多域分段保护算法。仿真表明,相比传统的多域保护算法,该算法阻塞率低,可扩展性好。     

Fault-tolerant routing over shortest node-disjoint paths in hypercubes

This paper presented a routing algorithm that finds n disjoint shortest paths from the source node s to target node d in the n-dimensional hypercube. Fault-tolerant routing over all shortest node-disjoint paths has been investigated to overcome the failure encountered during routing in hypercube networks. In this paper, we proposed an efficient approach to provide fault-tolerant routing which has been investigated on hypercube networks. The proposed approach is based on all shortest node-disjoint paths concept in order to find a fault-free shortest path among several paths provided. The proposed algorithm is a simple uniform distributed algorithm that can tolerate a large number of process failures, while delivering all n messages over optimal-length disjoint paths. However, no distributed algorithm uses acknowledgement messages (acks) for fault tolerance. So, for dealing the faults, acknowledgement messages (acks) are included in the proposed algorithm for routing messages over node-disjoint paths in a hypercube network.     

A Self-adaptive Algorithm for Topology Matching in Unstructured Peer-to-Peer Networks

Peer-to-peer networks are overlay networks that are constructed over underlay networks. These networks can be structured or unstructured. In these networks, peers choose their neighbors without considering underlay positions, and therefore, the resultant overlay network may have a large number of mismatched paths. In a mismatched path, a message may meet an underlay position several times, which causes redundant network traffic and end-to-end delay. In some of the topology matching algorithms called the heuristic algorithms, each peer uses a local search operator for gathering information about the neighbors of that peer located in its neighborhood radius. In these algorithms, each peer also uses a local operator for changing the connections among the peers. These matching algorithms suffer from two problems; neither the neighborhood radius nor the local operator can adapt themselves to the dynamicity of the network. In this paper, a topology matching algorithm that uses learning automata to adapt the neighborhood radius and an adaptation mechanism inspired from the Schelling segregation model to manage the execution of the local operator is proposed. To evaluate the proposed algorithm, computer simulations were conducted and then the results were compared with the results obtained for other existing algorithms. Simulation results have shown that the proposed algorithm outperforms the existing algorithms with respect to end-to-end delay and number of mismatched paths.     

Network coding based reliable disjoint and braided multipath routing for sensor networks

This paper presents network coding based reliable disjoint and braided multipath routing (NC-RMR ) for sensor networks, which forms multipath by hop-by-hop method and only maintains local path information of each node without establishing end-to-end paths. Neighbors of each local node are divided into groups according to their hops to sink nodes to improve the network load balancing. For further performance improvement of NC-RMR with disjoint multipath model, local nodes select their own backup nodes in neighbor nodes to form additional logical paths, which implement a braided multipath model. Security advantages of NC-RMR with multipath and network coding mechanisms are analyzed. Analytical and simulation results prove that braided multipath routing model has better performance over disjoint model, and NC-RMR protocol can reduce the required number of transmission paths, ensure load balance of sensor network system, reduce the energy consumption of nodes.     

An optimal inherently stabilizing routing algorithm for star P2P overlay networks

Star graphs possess many desirable properties such as scalable node degrees and diameters, which are essential to facilitate reduced routing table sizes and low maximum path length for routing in large P2P networks. In addition, because a large number of disjoint paths are available and each data/replica in an n‐star can be placed in an (n − 1)‐star, load balancing and alleviation of network bottlenecks can be implemented in star P2P overlay networks. Therefore, star networks have been proposed as viable alternatives to existing overlay topologies for large P2P networks. In this paper, we propose an optimal stabilizing and inherently stabilizing algorithm for routing messages over all disjoint paths between two peers in a star P2P overlay network. The algorithm is optimal in terms of its time complexity in rounds and the length of the longest path traversed by the messages, and fault tolerant due to being stabilizing and inherently stabilizing, allowing the system to withstand transient faults. The algorithm can be used to increase network reliability and survivability in P2P networks. In addition, the usage of all disjoint paths to route messages between two peers leads to increased network bandwidth while distributing the communication overhead across the network and eliminating network bottlenecks in P2P networks. Copyright © 2016 John Wiley & Sons, Ltd.     

Finding non-dominated bicriteria shortest pairs of disjoint simple paths

In this paper we introduce a method to compute non-dominated bicriteria shortest pairs, each including two disjoint simple paths. The method is based on an algorithm for ranking pairs of disjoint simple paths by non-decreasing order of cost, that is an adaptation of a path ranking algorithm applied to a network obtained from the original one after a suitable modification of the topology. Each path in this new network corresponds to a pair of paths in the former one. Computational results are presented and analysed for randomly generated networks.     

General-demand disjoint path covers in a graph with faulty elements

A k-disjoint path cover of a graph is a set of k internally vertex-disjoint paths which cover the vertex set with k paths and each of which runs between a source and a sink. Given that each source and sink v is associated with an integer-valued demand d(v)≥1, we are concerned with general-demand k-disjoint path cover in which every source and sink v is contained in the d(v) paths. In this paper, we present a reduction of a general-demand disjoint path cover problem to an unpaired many-to-many disjoint path cover problem, and obtain some results on disjoint path covers of restricted HL-graphs and proper interval graphs with faulty vertices and/or edges.     

基于SASR的多路径协议SAMSR研究

比较和分析了自组网络中单路径与多路径的反应式路由协议,在SASR的基础上提出了一个新的多路径路由协议SAMSR。它通过记录重复的RREQ报文以获得更多网络拓扑信息,从而发现更多的可达路径,以及在收到重复的RREP报文后,发回重选报文RSEL保证路径间的节点不相干性。最后通过在NS-2平台上模拟考查其性能,表明SAMSR协议虽然增加了网络开销,但提高了分组抵达率,减少了端到端的路由时延。     

A formal role-based access control model for security policies in multi-domain mobile networks

Mobile users present challenges for security in multi-domain mobile networks. The actions of mobile users moving across security domains need to be specified and checked against domain and inter-domain policies. We propose a new formal security policy model for multi-domain mobile networks, called FPM-RBAC, Formal Policy Model for Mobility with Role Based Access Control. FPM-RBAC supports the specification of mobility and location constraints, role hierarchy mapping, inter-domain services, inter-domain access rights and separation of duty. Associated with FPM-RBAC, we also present a formal security policy constraint specification language for domain and inter-domain security policies. Formal policy constraint specifications are based on ambient logic and predicate logic. We also use ambient calculus to specify the current state of a mobile network and actions within security policies for evaluation of access requests according to security policies. A novel aspect of the proposed policy model is the support for formal and automated analysis of security policies related to mobility within multiple security domains.     

Design schemes of dynamic rerouting networks with destination tag routing for tolerating faults and preventing collisions

In fault-tolerant multistage interconnection design, the method of providing disjoint paths can tolerate faults, but it is complicated and hard to choose a collision-free path in disjoint paths networks. A network with disjoint paths can concurrently send more identical packets from the source node to increase the arrival ratio or backtrack a packet to the source and take the other disjoint path, but these two methods might increase the collision ratio. In contrast, a dynamic rerouting method finds an alternative path that tolerates faults or prevents collisions. In this paper, we present methods of designing dynamic rerouting networks. This paper presents (1) three design schemes of dynamic rerouting networks to tolerate faults and prevent collisions; (2) design schemes that enable a dynamic rerouting network to use destination tag routing to save hardware cost in switches for computing rerouting tags; (3) a method to prevent a packet from re-encountering the faulty element again after rerouting to reduce the number of rerouting hops and improve the arrival ratio; and (4) simulation results of related dynamic rerouting networks to realize the factors which influence the arrival ratio including the fault tolerant capability and the number of rerouting hops. According to our proposed design schemes and according to our analysis and simulation results, a designer can choose an applicable dynamic rerouting network by using cost-efficient considerations. This paper was partially supported by the National Science Council NSC-92-2213-E-324-006- and NSC-94-2213-E-035-050-; and the partial part of the preliminary version of this paper was published by the conference ISPA 2005 [5].     

A multipath routing strategy to prevent flooding disruption attacks in link state routing protocols for MANETs

Multipath routing has been proposed to increase resilience against network failures or improve security in Mobile Ad Hoc Networks (MANETs). The Optimized Link State Routing (OLSR) protocol has been adopted by several multipath routing strategies. They implement Multipoint Relay (MPR) nodes as a flooding mechanism for distributing control information. Ideally, the construction of multiple disjoint paths helps to increase resilience against network failures or malicious attacks. However, this is not always possible. In OLSR networks, partial link-state information is generated and flooded exclusively by the MPRs. Therefore, the nodes only obtain a partial view of the network topology. Additionally, flooding disruption attacks may affect either the selection of the MPRs or the propagation of control traffic information. As a consequence, the chances of constructing multiple disjoint paths are reduced. We present a strategy to compute multiple strictly disjoint paths between any two nodes in OLSR-based networks. We provide mechanisms to improve the view of the network topology by the nodes, as well as handling potential flooding disruption attacks to the multipath construction mechanism in OLSR-based networks. We conduct simulations that confirm our claims.     

Pricing and brokering services over interconnected IP networks

In this paper we consider an IP-based communication platform, characterized by a novel architectural model where barrier-free business and market interactions can be performed. We assume that the network is able to deliver application services which need of network service performance guarantees. In this scenario, we present the concept of the network commodity that is traded in the marketplace among network service providers, application service providers and customers. Moreover, we use this concept to define a new usage-based tariff model. Then, we especially focus on the activity of the so-called Network Resource Brokers, which have the goal of finding the end-to-end inter-domain path to deliver an application service that maximizes the users' benefit, in terms of price and perceived service level. In this regard, we present a QoS-and-price based inter-domain routing algorithm, analyze its computational complexity, and show its effectiveness in a selected simulation scenario.     

Restoration by path concatenation: fast recovery of MPLS paths

A new general theory about restoration of network paths is first introduced. The theory pertains to restoration of shortest paths in a network following failure, e.g., we prove that a shortest path in a network after removing k edges is the concatenation of at most k+1 shortest paths in the original network. The theory is then combined with efficient path concatenation techniques in MPLS (multi-protocol label switching), to achieve powerful schemes for restoration in MPLS based networks. We thus transform MPLS into a flexible and robust method for forwarding packets in a network. Finally, the different schemes suggested are evaluated experimentally on three large networks (a large ISP, the AS graph of the Internet, and the full Internet topology). These experiments demonstrate that the restoration schemes perform well in actual topologies. Received: December 2001 / Accepted: July 2002 RID="*" ID="*" This research was supported by a grant from the Ministry of Science, Israel     

A tool for tracing network data plane via SDN/OpenFlow

SDN provides an approach to create desired network forwarding plane by programming applications. For a large-scale SDN network comprised of multiple domains and running multiple controller applications, it is difficult to measure and diagnose the problems of flow tables in data plane. Tracing the forwarding path of SDN is one of effective way for data plane state measurement. Previously proposed methods for debugging SDN were applied to a single administrative domain. There is less effort to trace the flow entries of the data plane in large-scale multi-domain SDN networks. In this paper, we propose a method of software defined data plane tracing in large-scale multi-domain SDN networks. Our method can trace forwarding paths, and get the matched flow entries and other customized trace information. We present the designs compatible with OpenFlow 1.0 and 1.3 switches. The performance and deployment effect are evaluated by simulation test and analysis. It shows that our method has better performance than traditional IP traceroute, and its deployment at about 20% of AS nodes can enable 70% of AS paths to be traceable.     

量子密钥分发网络端端密钥协商最优路径选择算法

针对量子密钥分发(QKD)网络端端密钥协商路径选择问题,设计了一种基于改进Dijkstra算法的端端密钥协商最优路径选择算法。首先,基于有效路径策略,剔除网络中的失效链路;然后,基于最短路径策略,通过改进Dijkstra算法,得到密钥消耗最少的多条最短路径;最后,基于最优路径策略,从多条最短路径中选择一条网络服务效率最高的最优路径。分析结果表明,该算法很好地解决了最优路径不唯一、最优路径非最短、最优路径非最优等问题,可以降低QKD网络端端密钥协商时密钥消耗量,提高网络服务效率。     

A framework of Voronoi diagram for planning multiple paths in free space

Most of the emphasis in path planning, a topic of much interest in several domains, has been on finding the optimal path or at most k optimal paths. However, in domains such as adversarial planning, one of the agents might deliberately take less optimal paths to confuse the opponent, and by the same token an agent, for inferring opponent's intent, has to consider all possible paths that the opponent might take. We introduce the notion of representative paths in free space (2D) and study the problem of computing all representative paths with different properties, such as all representative paths with at most L loops, among polygonal regions using a framework of Voronoi diagram. We prove three properties: (1) the upper and lower bounds to the number of simple paths in a Voronoi graph (2) given any path, a homotopic path can always be obtained from the Voronoi diagram of the regions and (3) all representative paths with a given property might not be always obtainable from the Voronoi graph even after searching the graph exhaustively and present an algorithm to work around this limitation. We also show how our findings can be applied for efficient entity re-identification, a problem involving a large number of dynamic entities and obstacles in the military domain.     

Techniques and Benefits of Energy-Aware Load-Distribution in Multi-domain Translucent Wavelength Switched Optical Networks

In this paper, we propose a novel inter-domain connection provisioning mechanism for multi-domain translucent Wavelength Switched Optical Networks. The mechanism can operate in hierarchical and non-hierarchical path computation element-based architectures. It is based on a novel approach to derive the domain abstract topologies jointly with an inter-domain routing algorithm. The overall objective is to perform end-to-end route computations for incoming connections. We do so by taking into account the current load of the physical links and some energy parameters of the optical network devices with the purpose of distributing the load (as much as possible) along the physical links and keeping the energy consumption low. The performance of the whole mechanism is highlighted through extensive and illustrative simulation results that benchmark it against shortest path-based techniques.