Self-healing algorithm for logical mesh connection on ring networks

A self-healing algorithm is proposed for a ring network connected as a logical mesh. It offers good performance in terms of protection line capacity, restoration time, and survivability against multiple failures     

Self-healing in wideband packet networks

A brief overview is given of wideband packet technology (WPT), with special attention to the features affecting the feasibility of self-healing, a method for automatic failure recovery proposed herein. The objectives of self-healing are set forth, and the failure detection strategy is described. With this strategy, nondisruptive trunk monitoring (self-monitoring) at the data link layer of an open system interconnection (OSI) reference model is performed to detect facility failure of under 1 s. The bit error rate (BER) on a transmission link is estimated on the basis of counts of the number of packets with cyclic redundancy check (CRC) errors at the data link layer. This failure detection strategy can respond to link failures for any given traffic mix by the provisioning of duration and level of unacceptable sustained BER. The mechanisms used to achieve recovery in frame-relay networks using packet streams to carry users' traffic are discussed. Provisioning of the WPT nodes and the network is addressed     

Self-healing virtual path architecture in ATM networks

ATM network techniques have been actively researched and developed with the goal of realizing B-ISDN. ATM networks can transport signals of various services efficiently and economically, and offer the benefit of enhanced flexibility if the virtual path (VP) concept is adopted. Therefore, the ATM network will provide the infrastructure for B-ISDN. One of the most important themes in B-ISDN is the increased level of network reliability required to to match the high volume of data transmission that will be incurred by the information society and the “mission critical” nature of such data. The authors summarize self-healing network (SHN) schemes they have developed, and discuss problems that must be solved to realize SHN     

Self-healing ATM networks based on virtual path concept

This paper proposes self-healing network techniques suitable for ATM networks in order to realize a high-reliablity B-ISDN. First, the characteristics of the virtual paths (VP) and their influence on failure restoration are discussed. A high-speed restoration technique which exploits the benefits of the VP is then proposed and described. The technique simplifies the message transmission processes and reduces the number of generated messages by using preassigned backup virtual paths. Next, the scheme used to design the backup VP routes and spare resource distribution for each link is proposed in order to create a network that applies the proposed restoration scheme. Next, self-reconstruction techniques of backup virtual paths are proposed for the realization of a reversionless restoration cycle. Finally, the feasibility of the distributed control operation is discussed     

Resilient burst ring: extend IEEE 802.17 to WDM networks

In this article, a novel network architecture called resilient burst ring is proposed to implement the next-generation WDM-supported ultrahigh- speed (100 gigabit or higher) carrier Ethernet. This architecture inherits all the best features of resilient packet ring (IEEE 802.17), provides a burst-mode data transmission scheme through a two-sublayer (optical and electronic) hierarchy, and realizes the WDM-supported ultra-high-speed Ethernet with scalability and reliability. RBR adopts a two-layer buffering scheme to resolve the contentions of optical burst packets and provides three different data transmission modes. With the proposed Priority- Only-Destination-Delay resource reservation control protocol, RBR can provide a flexible QoS strategy to implement the transmission of all of the applications and services in existing networks.     

Responsive on-line gateway load-balancing for wireless mesh networks

We propose an adaptive online load-balancing protocol for multi-gateway Wireless Mesh Networks (WMNs) which, based on the current network conditions, balances load between gateways. Traffic is balanced at the TCP flow level and, as a result, the aggregate throughput, average flow throughput and fairness of flows improves. The proposed scheme (referred to as Gateway Load-Balancing, GWLB) is highly responsive, thanks to fast gateway selection and the fact that current traffic conditions are maintained up-to-date at all times without any overhead. It also effectively takes into account intra-flow and inter-flow interference when switching flows between gateway domains. We have found the performance achievable by routes used after gateway selection to be very close to the performance of optimal routes found by solving a MINLP formulation under the protocol model of interference. Through simulations, we analyze performance and compare with a number of proposed strategies, showing that GWLB outperforms them. In particular, we have observed average flow throughput gains of 128% over the nearest gateway strategy.     

Sensor and gateway location optimization in body sensor networks

In body sensor networks (BSNs), energy-constrained sensors monitor the vital signs of human beings in healthcare applications. Energy consumption is a fundamental issue, since BSNs must operate properly and autonomously for long period of time without battery recharge or replacement. In addition, the human exposure to electromagnetic radiation must be limited. For all these reasons, the energy consumption in BSNs should be minimized. In this paper, sensor and gateway location optimization for BSNs has been analyzed. A mathematical model has been proposed to minimize the energy consumption of the BSN and the heating effects on human tissues. We distinguish between ‘in-body’ and ‘on-body’ sensors depending on their location inside or outside the human body, respectively. The theoretical analysis and the numerical results reveal that in in-BSNs the energy consumption can be significantly reduced when the optimal positions of the gateway or the sensors are computed. However, in on-BSNs the energy consumption is not affected by the devices’ location. With power control the interferences are minimized and the human exposure to electromagnetic radiation is reduced.     

Highly reliable optical bidirectional path switched ring networks applicable to photonic IP networks

The reliability of the optical bidirectional path switched ring (OBPSR) network is studied by using optical networking equipment (ONE) with microelectromechanical system (MEMS)-based optical switching fabrics. The reliability of the wavelength path in OBPSR networks is shown to be highly dependent on redundant schemes of switching fabrics in the ONE. This study proposes a new redundant scheme utilizing optical couplers together with controlled switch fabrics without using active selectors, and shows that reliability of the wavelength path can be remarkably improved. A fast redundant switching operation of 10 ms was experimentally confirmed with a prototype of the ONE based on the proposed redundant switching fabrics. Furthermore, interworking operations in terms of the protection and restoration between the optical layer and the Internet protocol (IP) layer are experimentally investigated. In a 500-km optical ring network, fast wavelength path protection switching was confirmed without reconfiguring the link state database of the IP layer, and the measured protection time in the IP layer was as short as 21 ms.     

K-terminal reliability in ring networks

The authors present a new formula for computing K-terminal reliability in a communication network whose stations and links (vertices and edges) form a network graph G having a ring topology, where K-terminal reliability is the probability R_K(G) that a subset of R specific terminal stations in G can communicate. This new formula is applied to three Fiber Distributed Data Interface (FDDI) ring-network topologies, and for each topology the authors derive closed-form polynomial expressions of R_K(G) in terms of the failure probabilities of links, network ports, and station common units. The authors define the concept of the K-minimal Eulerian circuit and use combinations of these circuits to obtain K-graphs and their resulting dominations, thus extending the use of K-graphs to ring networks in which data messages, tokens, or other control frames traverse operative network links with an Eulerian tour. Distinct K-graphs having a nonzero sum of dominations are called noncanceled K-graphs and correspond exactly to terms in closed-form polynomial expressions of R_K(G). The authors show that trees have only one K-graph and that counter-rotating dual rings and rings of trees have at most 2K+1 noncanceled R-graphs. These results contribute the first closed-form polynomial R-terminal reliability expressions for the ring-of-trees topology. The results are useful in evaluating dependability, reliability, availability, or survivability of token rings and similar networks     

WDM环形网若干问题的研究

研究了 WDM环形网存在的主要问题 ,特别是环网自愈所存在的基本问题 ,如信令传送以及故障判定、定位、隔离 ,并给出了一些解决方案。另外还研究了光器件的瞬态响应对 WDM环网的影响。     

Metro WDM networks: performance comparison of slotted ring and AWG star networks

Both wavelength-division-multiplexing (WDM) networks with a ring architecture and WDM networks with a star architecture have been extensively studied as solutions to the ever increasing amount of traffic in the metropolitan area. Studies typically focus on either the ring or the star and significant advances have been made in the protocol design and performance optimization for the WDM ring and the WDM star, respectively. However, very little is known about the relative performance comparisons of ring and star networks. In this paper, we conduct a comprehensive comparison of a state-of-the-art WDM ring network with a state-of-the-art WDM star network. In particular, we compare time-slotted WDM ring networks (both single-fiber and dual-fiber) with tunable-transmitter and fixed-receiver (TT-FR) nodes and an arrayed-waveguide grating-based single-hop star network with tunable-transmitter and tunable-receiver (TT-TR) nodes. We evaluate mean aggregate throughput, relative packet loss, and mean delay by means of simulation for Bernoulli and self-similar traffic models for unicast traffic with uniform and hot-spot traffic matrices, as well as for multicast traffic. Our results quantify the fundamental performance characteristics of ring networks versus star networks and vice versa, as well as their respective performance limiting bottlenecks and, thus, provide guidance for directing future research efforts.     

A compatible fixed-frame ISDN gateway for broadband metropolitan area networks

A method (referred to as I-SWIFT) is presented for integrating the flow of synchronous voice streams into existing broadband cable systems. The interface between the integrated voice subnetwork and the cable system is realized by a metropolitan area gateway (MAG) implemented at the broadband cable headend. In I-SWIFT, an intelligent scheduling algorithm in the MAG dynamically allocates channel bandwidth using modified data switch-filtering techniques. The MAG accomplishes this by establishing a fixed voice frame (with realignment) which is implemented in an upwardly compatible fashion with respect to the existing carrier-sense multiaccess communication with collision detection (CSMA/CD) data stations. Thus, previously installed stations require no modification. It is shown that for typical system design parameters, the I-SWIFT gateway approach can achieve much improved performance over previous compatible voice/data integration methods     

MOSIS-a gateway to silicon

The MOSIS Service, a low-cost prototyping service for standard-cell and full-custom VLSI circuit development, is discussed. MOSIS (an acronym for MOS Implementation System) has developed a methodology that allows the merging of many different projects from various organizations onto one wafer. This cost-sharing gives designers opportunities that might be prohibitive at regular commercial prices. Since designs are combined on a single mask set. MOSIS users pay for only the fraction of the silicon that they use. Runs are scheduled on a regular basis for 3.0-, 2.0-, 1.6-, and 1.2-μm double-metal CMOS/bulk technologies. MOSIS quality control and access to MOSIS are described     

Integrity of public telecommunications networks

Provides an overview of the special issue of the IEEE Journal of Communications, Volume 12, Number 1 (January 1994) which addresses open questions in network integrity, reliability and survivability. Current progress in this area is discussed. The questions addressed include user survivability perspectives on standards, planning, and deployment; the analysis and quantification of network disasters; survivable and fault-tolerant network architectures and associated economic analyses; and techniques to handle network restoration as a result of physical damage or failures in software and control systems. Special interests are devoted to the survivability of broadband networks employing the new transport/switching techniques based on the synchronous optical network (SONET) and asynchronous transfer mode (ATM) standards due to their emerging role in future B-ISDN. Network integrity due to failures of common channel signaling (CCS) systems is also very critical. The present special issue includes 22 papers and is organized into the following sections: user perspectives and planning, software quality and reliability, network survivability characterization and standards, network restoration for SONET networks, network restoration for ATM networks, traffic effect and performance enhancement for computer networks, and survivable network design methods. Network restoration methods for SONET, ATM, and computer networks correspond to those for the physical layer (SONET), ATM layer, and the network layer, defined in the CCITT broadband ISDN layer structure     

Frame relay in public networks

Frame relay is a significant networking technology in the current data networking environment. Given its inherent advantages, it is particularly well-suited to LAN interconnection. In a public network, frame relay has key advantages for end users in terms of performance and cost efficiency. The effectiveness of frame relay in public networks, the management of public frame relay networks, the evolution from frame to cell services, and product implementations are discussed. The advantages frame relay has over existing technologies are described     

Applications of public gigabit networks

Applications likely to require gigabit-per-second communications, including supercomputer networking, remote visualization, and virtual reality, are presented. Specifically, dynamic radiation therapy planning, visualization and telepresence, and medical imaging applications are examined. Public gigabit network requirements, applications of broadband ISDN to gigabit networks, the needs of applications with B-ISDN, and distance hiding in public gigabit networks are discussed     

Performance analysis of CSMA/CD networks with a buffered gateway

A single CSMA/CD (carrier sense multiple access with collision detection) local area network which is connected to other networks by a gateway with finite buffer capacity is described. Its performance is analyzed by using an embedded Markov chain. For the service discipline of packets queuing at the gateway, three cases are considered: G-limited service discipline, E-limited service discipline, and G-decrementing service discipline. The state transition of the system is analyzed, and the Laplace-Stieltjes transforms of the probability distribution functions of idle and busy periods are derived. Equations for average performance measures are formulated. Numerical examples are used to examine the effect of external traffic on the packet delay and throughput at terminals as well as at the gateway for each service discipline. The results show that as a service discipline at the gateway, the limited service disciplines are preferable to the decrementing service discipline in that they more fairly allocate the channel bandwidth to terminals and the gateway. The numerical results also show that the performance of the gateway is substantially improved by using a higher retransmission rate at the gateway