A network management architecture for robust packet routing in meshoptical access networks

We describe an architecture for an optical local area network (LAN) or metropolitan area network (MAN) access. The architecture allows for bandwidth sharing within a wavelength and is robust to both link and node failures. The architecture can be utilized with an arbitrary, link-redundant mesh network (node-redundancy is necessary only to handle all node failures), and assumes neither the use of a star topology nor the ability to embed such a topology within the physical mesh. Reservation of, bandwidth is performed in a centralized fashion at a (replicated) head end node, simplifying the implementation of complex sharing policies relative to implementation on a distributed set of routers. Unlike a router, however, the head end does not take any action on individual packets and, in particular, does not buffer packets. The architecture thus avoids the difficulties of processing packets in the optical domain while allowing for packetized shared access of wavelengths. We describe the route construction scheme and prove its ability to recover from single link and single node failures, outline a flexible medium access protocol and discuss the implications for implementing specific policies, and propose a simple implementation of the recovery protocol in terms of state machines for per-link devices     

All-optical four-fiber bidirectional line-switched ring

An all-optical four-fiber bidirectional line-switched ring (O-4F/BLSR) architecture is proposed. This new physical layer networking protocol uses wavelengths as tributaries and an optical supervisory channel to carry overhead information. Optical channels can be added and dropped from the ring, and virtual wavelength paths can be provisioned. Both node and link failures of a network can be protected through a two layer protection scheme. Protection switching within the optical multiplex section layer (OMS) restores failure caused by loss of optical continuity in a way similar to the SONET 4F/BLSR line switching. Protection switching within the optical channel layer restores single channel failure using 1:N protection. Test results show that the O-4F/BLSR can restore traffic in less than 50 ms. A self-healing, bandwidth efficient, and scalable all-optical transport network evolving from this O-4F/BLSR architecture is possible     

Hybrid Control and Reservation Architecture for Multidomain Burst Switched Network

Optical burst switching realizes all-optical communication by dividing data transmission system into control plane and data plane. In order to implement control plane two controlling mechanisms such as distributed and centralized control and reservation models have been presented in literature. Both of the architectures have pros and cons associated such as distributed model lacks efficient resource utilization while centralized model is nonscalable. In order to overcome these, a new hybrid control and reservation mechanism has been presented by the authors. The proposed model is based on clustering technique where each cluster consists of cluster head and member nodes. Cluster head performs major functionalities in the network such as path establishment, routing and resource management, fault management, etc., while member nodes perform data switching functionality. In order to implement the architecture, a signaling protocol is also presented. In this paper, we discuss different scenarios required for the implementation of the proposed hybrid model. These scenarios detail the message dialogs exchange between different network nodes and between different software modules during lightpath establishment, data transmission, and connection teardown operations. The goal of efficient resource utilization is achieved through centralized control of network resources while scalability is achieved through dividing the network into multiple domains. Finally, the simulation section shows the mechanism of designing the multidomain architecture, network bandwidth utilization comparison and reduction in end-to-end data transmission latency.      

Light-mesh — A pragmatic optical access network architecture for IP-centric service oriented communication

Contemporary deployments of optical access networks are based on the principles of Passive Optical Networks (PONs). PONs deploy a star topology and dual wavelength for communication between the center and ends of a star. The star topology requires that each end-user be connected to the star splitter (usually a passive coupler). We argue in this paper that while adhering to the requirements of access networks, we are able to provide a better topological solution in terms of the cost-factor and the ability to upgrade to a greater bandwidth. This solution, called a light-mesh, is based on the concept of pragmatic optical packet transport or light-frames results in a unique node architecture, interconnection matrix, and communication protocols. We begin by investigating into the node architecture that is required for a mesh network in the access area. The proposed node architecture has unique benefits in terms of being able to support the intermittent communication in the access area — nodes are not always powered ON, despite which, it is important to maintain mesh connectivity. Hence we propose the use of largely passive components in node architecture design. Passive components in a mesh lead to collisions of packets in the access area, for which we propose a unique collision detection and recovery scheme based on a logical time-overlap method. Collisions make the end-to-end delay uncertain. Analysis of the associated delay is performed. We then propose algorithms to build such a light-mesh network. These algorithms are investigated in terms of network built-out costs and these costs are compared to a PON topology. Cost differences and a performance comparison with PON are presented as part of the numerical analysis.     

Architectural analysis of multiple fiber ring networks employingoptical paths

Analyzes the performance of various types of multiple fiber ring networks employing optical paths (OP's). The multiple fiber ring network architecture is suitable for achieving failure resilient networks that have extremely large bandwidth but are still upgradable against future increases in traffic. This architecture will overcome the limitation of conventional WDM rings in terms of network expansion capabilities, the number of nodes within the ring, and the number of OP's accommodated in the network. The generic node architecture suitable for multiple fiber ring networks is presented and functionality requirements are identified. The OP accommodation design algorithms that minimize the required node system scale are proposed. Based on the generic node architecture and proposed OP accommodation design algorithms, we evaluated the performance of several types of multiple fiber rings in terms of the required node system scale for rings under various conditions. The effect of the ring architecture (uni-/bidirectional rings), optical path schemes (wavelength path/virtual wavelength path), and different node connectivity patterns are demonstrated for the first time. The obtained results elucidate the criteria for selecting the most suitable multiple fiber ring architecture     

一种可部署在重路由光网络中实现有效连接管理的策略——基于分布式代理与蚁群算法

在大型骨干光网络中, 建立一条从源节点到宿节点的路由至关重要。在集中式网络管理系统体系下, 网络中动态路由信息以及故障状态信息, 通过路由的“泛洪”机制, 被传送到其他节点上实现资源信息共享,这对于连接的迅速建立, 恢复路由的快速启动将是不利的。尝试采用一种启发式算法-蚁群策略, 快速提高光网络中故障恢复的速度。该路由算法平台采用了分布式蚁群算法自动修复故障点, 解决了重路由的快速收敛问题; 依靠分布式代理机制构建管理平面和数据平面相互通信的机制, 完成诸如链路信息素的更新等功能。设计了一个网络故障的场景, 通过实验数据表明, 采用蚁群的分布式路由策略, 可以更快地实现路由信息的汇聚, 找到最佳的恢复路由。     

PROTECTORATION: a fast and efficient multiple-failure recovery technique for resilient packet ring using dark fiber

The two protection methods wrapping and steering used in IEEE 802.17 resilient packet ring (RPR) provide fast but very inefficient and limited network failure recovery. Due to the increased length of the backup path, RPR suffers from high traffic loss, a decreased throughput-delay performance, and the lack of resilience against multiple link and/or node failures. To achieve an improved resilience, interconnecting a subset of the ring nodes by means of a dark-fiber single-hop star wavelength division multiplexing (WDM) network is proposed. In doing so, the ring network is divided into separate domains, each being fully recoverable from a single link or node failure without losing full network connectivity. A novel hybrid fault recovery technique, termed protectoration, is proposed and examined by means of probabilistic analysis and simulation in terms of stability, channel utilization, and throughput-delay performance. The proposed protectoration technique 1) combines the fast recovery time of protection and the bandwidth efficiency of restoration, 2) provides full recovery from multiple link and node failures, 3) builds on both wrapping and steering protection methods of RPR and, thus, allows for an evolutionary upgrade of existing RPR networks, and 4) does not require the convergence of routing protocols in response to failures and, thus, improves the routing stability and network availability. Numerical investigations in this paper show that the location of failures has a strong impact on the network performance. For a given failure location, the protectoration technique is able to accommodate multiple ring failures without significant performance loss.     

Spectrum-efficient optical drop-add-drop network with a centralized multi-carrier light source

Traditional ROADM networks strictly follow the coarse ITU-T standard wavelength grids and channel spacings, which would result in low optical spectrum utilizations under dynamic traffic requests of variable spectrum lightpaths. This paper presents a spectrum-efficient optical drop-add-drop network with a centralized multi-carrier light source (C-MCLS). The C-MCLS generates thousands of optical carriers with uniform and narrow channel spacings. The optical carriers are distributed to each network node as light sources on demand through ROADMs designed with the carrier-drop function. Spectrum-aware optical carrier allocation is studied first in the proposed network. This paper proposes a Minimum Fragmentation Request First (MinFragRF) optical carrier allocation algorithm compared with the Maximum Spectrum Request First (MaxSRF) and Minimum Spectrum Request First (MinSRF) allocation algorithms. This paper also studies how channel spacings of optical carriers impact on the network performance under variable traffic demands. We perform both network analysis and simulations to evaluate the network performance in terms of the lightpath blocking probability (LP_BP) and the effective spectrum efficiency. We analytically derive the formulas of LP_BP and average effective spectrum efficiency in the proposed network. Simulation results show that the proposed network with more narrow channel spacings greatly reduces the lightpath blocking probability compared with the traditional ROADM network. The average effective spectrum efficiency of the proposed network can be improved about 100 % compared with that of the traditional ROADM network by choosing appropriate network design parameters. The MinFragRF allocation algorithm has a better LP_BP performance than that of the MaxSRF and has a better spectrum utilization efficiency than that of the MinSRF. The optimal channel spacing evaluations show that narrow channel spacings such as 6.25 and 12.5 GHz greatly improve LP_BP performance when low bit-rate traffic requests dominate in the traffic model. However, as the high bit-rate traffic requests increase, the performance advantage of narrow channel spacings is gradually disappearing.     

Generalized loop-back recovery in optical mesh networks

Current means of providing loop-back recovery, which is widely used in SONET, rely on ring topologies, or on overlaying logical ring topologies upon physical meshes. Loop-back is desirable to provide rapid preplanned recovery of link or node failures in a bandwidth-efficient distributed manner. We introduce generalized loop-back, a novel scheme for performing loop-back in optical mesh networks. We present an algorithm to perform recovery for link failure and one to perform generalized loop-back recovery for node failure. We illustrate the operation of both algorithms, prove their validity, and present a network management protocol algorithm, which enables distributed operation for link or node failure. We present three different applications of generalized loop-back. First, we present heuristic algorithms for selecting recovery graphs, which maintain short maximum and average lengths of recovery paths. Second, we present WDM-based loop-back recovery for optical networks where wavelengths are used to back up other wavelengths. We compare, for WDM-based loop-back, the operation of generalized loop-back operation with known ring-based ways of providing loop-back recovery over mesh networks. Finally, we introduce the use of generalized loop-back to provide recovery in a way that allows dynamic choice of routes over preplanned directions     

D2F: A Routing Protocol for Distributed Data Fusion in Wireless Sensor Networks

Data fusion can be distributed into network and executed on network nodes, to reduce data from redundant sensor nodes, to fuse the information from complementary sensor nodes and to get the complete view from cooperative nodes. Consequently only the inference of interest is sent to end user. This distributed data fusion can significantly reduce the data transmission cost and there is no need for a powerful centralized node to process the collected information. However, to achieve the advantages of distributed data fusion and better utilization of network resources, each fusion function needs to be performed at particular network node for minimizing energy cost of data fusion application, both data transmission cost and computation cost. In this paper, distributed data fusion routing (D2F) is proposed, which is designed for deploying distributed data fusion application in wireless sensor networks. D2F can find the optimal route path and fusion placements for a given data fusion tree, which obtains the optimal energy consumption for in-network data fusion. D2F can also handle different link failures and maintain the optimality of energy cost of data fusion by adapting to the dynamic change of network.     

Multiple-star wavelength-router network and its protection strategy

A wavelength division multiplexed (WDM) multiple-star network and its accompanying path and router protection strategies are proposed for interconnecting N major switch nodes in a national-scale telecommunications network. For a single path failure and uniform traffic matrix, fiber requirements are shown to be less than for a WDM ADM ring, while providing greater resilience to multiple path failures. “Adding” and “dropping” only whole wavelength channels between node pairs is found to lead to severe design instabilities and overinvestment in fiber, and time-sharing of wavelength channels is recommended to minimize fiber quantities. A star network capable of interconnecting N=22 switch nodes and an all-optical path protection switching method are verified experimentally, using a 16-channel 2,5-Gbit/s WDM system and a 22×22-port bulk-optics wavelength multiplexer as the hub router. Protection switching speeds within 50 ms are projected for a national-scale network     

A Portable Fiber Optic Local Area Network

A portable fiber optic local area network has been implemented for emergency command center communications. This network operates under a carrier sense multiple-access (CSMA) protocol and employs an architecture based on a unique active star node. The node consists of a transmissive optical star coupler and active electro-optical transceivers. Terminal-to-node or node-to-node links may be as long as 1 km. An architecture developed around this node design is capable of modular expansion to accommodate a large number (several hundread) of data subscribers. In addition to data services, this network can support broadcast video and integrated technical control.     

利用WDM和OADM实现铁路各站光接入

文章提出了一种基于密集波分复用器(DWDM)和光分插复用器(OADM)、以物理拓扑为总线型、逻辑拓扑为星形的适合于铁路通信各站光接入的光传输网方案,描述了光节点结构及这种网络的波长重复利用和自愈保护功能,实验测试了逻辑单星形光网络的传输特性,分析了网络规模的限制因素.     

Extensible optical access network enabling multistage protections and data aggregation based on tangent rings

In this paper, an extensible optical access network architecture is proposed on the basis of multiple tangent single‐fiber rings. With the proposed architecture, both multistage protections and data aggregation can be realized. Optical line terminal and remote nodes (RNs) can automatically switch to protection mode to overcome fiber failure occurring in both main ring (MR) and sub‐rings (SRs). The RNs, which are designed as tangent points, can realize wavelengths adding and dropping between MR and SRs, and they also can realize the network expansion conveniently and smoothly through adding more wavelengths. So, it is a good selection for next‐generation large‐scale access networks. Copyright © 2013 John Wiley & Sons, Ltd.     

Seamless Maintenance and Protection Scheme for Next-Generation Access Networks

We propose and demonstrate a seamless maintenance and protection scheme based on remotely reconfigurable remote node. Protection for fiber failures and a centralized optical time-domain reflectometry test for preventive maintenance can be achieved within 90 ms by using instantaneous optical powering at the central office, while maintaining the passive nature of the passive optical network.      

Gigabits-per-second optical interconnection networks:fault-tolerance with and without optical amplifiers

This paper quantifies the power budget concerns with respect to the number of consecutive faults that must be tolerated before a network can fail. In particular, it is shown that multiple consecutive failures may have a serious adverse effect on the speed of gigabit optical networks. Results indicate that, with 20 nodes using simple direct-detection, only passive star networks can operate at Gb/s in the event of multiple consecutive faults. Use of optical preamplifiers is shown to remedy this shortcoming substantially: even with 3 consecutive node failures, optical networks with passive star couplers or single couplers can achieve Gb/s transmission speed for a node spacing of up to 2.3 km     

Fault tolerant multiwavelength optical rings with limitedwavelength conversion

This paper presents methods for recovering from channel failures, link failures, and node failures in wavelength-division multiplexed (WDM) point-to-point links and ring networks with limited wavelength conversion/switching capabilities at the nodes. Different recovery schemes are presented to handle each type of failure. Each scheme is evaluated based on the network hardware configuration required to support it and the performance and management overheads associated with fault recovery. Although similar recovery techniques have been used in conventional networks such as SONET, the constraints due to limited wavelength conversion require new and more complex solutions     

Data Transmission Scheme Considering Node Failure for Blockchain

In recent years, Blockchain technology has attracted considerable attention from the industrial circle. Blockchain is a distributed ledger technology, which must be validated, stored and maintained by all nodes to ensure data security, transparency, and integrity. The communication efficiency of Blockchain is an important factor restricting its application. Existing algorithms can provide data routing schemes for Blockchain but without considering the node failure. On Blockchain, node failure is a common phenomenon due to the nodes’ selfishness and nodes’ mobility. Node failure degrades the network performance or even sometimes makes the network useless. This paper proposes a data transmission scheme considering node failure for finishing validation of block data on Blockchain, which firstly sets response threshold level to detect failure node, and then using greedy idea constructs communication tree to organize all nodes forwarding block data. Based to the multi-link concurrent communication tree model, this scheme maximizes the potential transmitting capacity of nodes and assigns proper tasks to other nodes beside source node, so it can shorten the validation time of Blockchain transaction, and improve resistance to node failure. Theoretical proof and experimental results show the effectiveness and the efficiency of the proposed data transmission scheme.     

Preconfiguring IP-over-Optical Networks to Handle Router Failures and Unpredictable Traffic

We consider the realization of traffic-oblivious routing in IP-over-optical networks where routers are interconnected over a switched optical backbone. The traffic-oblivious routing we consider is a scheme where incoming traffic is first distributed in a preset manner to a set of intermediate nodes. The traffic is then routed from the intermediate nodes to the final destination. This splitting of the routing into two phases simplifies network configuration significantly. In implementing this scheme, the first and second phase paths are realized at the optical layer with router packet grooming at a single intermediate node only. Given this unreliability of routers, we consider how two-phase routing in IP-over-optical networks can be made resilient against router node failures. We propose two different schemes for provisioning the optical layer to handle router node failures-one that is failure node independent and static, and the other that is failure node dependent and dynamic We develop linear programming formulations for both schemes and a fast combinatorial algorithm for the second scheme so as to maximize network throughput. In each case, we determine (i) the optimal distribution of traffic to various intermediate routers for both normal (no-failure) and failure conditions, and (ii) provisioning of optical layer circuits to provide the needed inter-router links. We evaluate the performance of the two router failure protection schemes and compare it with that of unprotected routing     

ZBFR: zone based failure recovery in WSNs by utilizing mobility and coverage overlapping

Wireless sensor networks are more prone to failures as compared to other traditional networks. The frequent faults and failures sometime create large holes causing loss of sensing and connectivity coverage in the network. In present work, a zone based failure detection and recovery scheme is presented to reliably handle such node failures. We first propose a consensus and agreement based approach to elect a suitable monitor node called as zone monitor (ZM). ZM is responsible for coordinating failure recovery activities and maintaining desired coverage within a zone. In order to overcome failure overhead due to false failure detection, a consensus is carried out amongst neighboring nodes of a suspicious node to confirm the correct status with high accuracy. On confirmation of a node failure, the impact of resulting hole on coverage is analyzed and if impact exceeds beyond a particular threshold, a recovery process is initiated. The recovery process utilizes backup nodes having overlapping sensing coverage with failed node and may also relocate some nodes. Firstly a backup node is probed and activated if available. If no backup node is found, the solution strives to recover coverage jointly by recursively relocating some mobile nodes and probing backup nodes. The proposed scheme is analyzed and validated through NS-2 based simulation experiments.