Multiple Backup Paths Research Articles

Blocking aware offline survivable path provisioning of connection requests in elastic optical networks

Survivability of Elastic Optical Networks (EONs) from a link failure is an important problem. Shared Backup Path Protection (SBPP) is widely used for protection against a link failure. Backup Spectrum Reservation with Multi Path Protection (BSR-MPP) was introduced to increase backup spectrum sharing by reserving backup spectrum and employing protection with multiple backup paths. We propose a new polynomial-time strategy, Blocking Aware Survivable Path Provisioning (BASPP) that shares backup resources like SBPP and BSR-MPP but can reduce request blocking when opportunity of sharing resources does not exist. Since we address the offline problem of Survivable Routing, Modulation and Spectrum Allocation in EONs, we also propose an Integer Linear Program formulation. Results show appreciable reduction in bandwidth blocking ratio by using BASPP over existing strategies.

XT-considered multiple backup paths and resources shared protection scheme based on ring covers.

With the rapid development of space division multiplexing (SDM) and flexible grid technology, the problem of resource allocation in optical network becomes much more complicated. Although there emerge a substantial number of works about link protection or restoration in SDM-EONs mesh networks, the topic of survivability is dug deeper in this work. It is acknowledged that protection schemes based on ring covers bring the advantages of shorter restoration time and lower costs. However, the RSCA problem in SDM-EON for link protection based on ring covers has rarely been investigated. To enhance the survivability of SDM-EON and make the best use of ring covers, we initially select a set of rings for the protection of all the links in a network topology according to constrains, aiming at taking full advantages of network resources. After that, we propose an algorithm to recover the traffic which will break off under link failures, basing on the set of rings. At the end of this protection scheme, we arrange the resources fulfilling the constrains of spectrum contiguity and core continuity constrains by using several different algorithms considering physical impairment. Based on the allocation in both spacial and spectral dimensions, our algorithms achieve better results of survivability. According to the simulations conducted for the evaluation of the proposed algorithms, our algorithms manage to recover at least 72.8% of traffic when the traffic request number is set to be 1000.

Alternate Path Selection in IP Networks using Bandwidth Optimization

Computer communication has been going through major changes throughout the last decades. Since TCP/IP was a protocol designed for wired networks, wireless transmission poses unique challenges to the well-defined and rigid protocol stack. Routing in ISP environment is challenging the clear path when the IP link was failure. In this paper, a Cross-layer approach is used to minimize routing disruption in IP networks. A model called probabilistically correlated failure (PCF) model was developed to quantify the impact of IP link failure on the reliability of backup paths. In PCF model, an algorithm is used to choose multiple reliable backup paths to protect each IP link. When an IP link fails, its traffic is split onto multiple backup paths to ensure that the rerouted traffic load on each IP link does not exceed the usable bandwidth. To evaluate this issue, the system has to be developed with real ISP service in particular network topology support. Entire path is initially used to select specific path, then backed up path are reused and tested by splitting entire bandwidth based on usage. The probability result will ensure the reliability and dedicated path of data transfer purpose. This kind of approach resolve the issue rose at high end data transaction application like VOIP, Video streaming etc.

Cross-Layer Approach for Minimizing Routing Disruption in IP Networks

Backup paths are widely used in IP networks to protect IP links from failures. However, existing solutions such as the commonly used independent model and Shared Risk Link Group (SRLG) model do not accurately reflect the correlation between IP link failures, and thus may not choose reliable backup paths. We propose a cross-layer approach for minimizing routing disruption caused by IP link failures. We develop a probabilistically correlated failure (PCF) model to quantify the impact of IP link failure on the reliability of backup paths. With the PCF model, we propose an algorithm to choose multiple reliable backup paths to protect each IP link. When an IP link fails, its traffic is split onto multiple backup paths to ensure that the rerouted traffic load on each IP link does not exceed the usable bandwidth. We evaluate our approach using real ISP networks with both optical and IP layer topologies. Experimental results show that two backup paths are adequate for protecting a logical link. Compared with existing works, the backup paths selected by our approach are at least 18 percent more reliable and the routing disruption is reduced by at least 22 percent. Unlike prior works, the proposed approach prevents the rerouted traffic from interfering with normal traffic.

A Novel Clustering Topology Control for Reliable Multi-hop Routing in Wireless Sensor Networks

The reliability of wireless sensor networks is significant in certain applications, especially the reliable routing. Most existing routing protocols use multi-paths to improve routing reliability. However, multi-paths waste a large amount of energy to obtain redundancy. This is not an optimal option for sensor nodes with limited energy. In this paper, a novel clustering-based reliable multi-hop routing algorithm ( CRMR ) is proposed. The algorithm adopts a mechanism of multiple backup cluster heads efficiently to extend time of stable period of clusters and to decrease energy consumption for reconstructing clusters. The local reconstruction of clusters is addressed for improving coverage, maintaining connectivity, and extending the network lifetime. While the algorithm overcomes the randomicity of selecting cluster heads and ensures well proportioned clusters. Employing backup cluster heads and gateways can ensure reliability of routing and overcome disadvantages of most existing reliable routing protocols, which is to preserve multiple backup paths. The algorithm adopts query driving data transmission mode for finding routes and bypassing unavailable routing nodes for backtracking to ensure the speediness of data transmissions and the reliability. The simulation results show that the algorithm can achieve good performance on both routing reliability and energy consumption.

Near optimal routing and capacity management for PWCE-based survivable WDM networks

Protected Working Capacity Envelope (PWCE) has been proposed to simplify resource management and traffic control for survivable WDM networks. In a PWCE-based network, part of the link capacity is reserved for accommodating working routes, and the remaining capacity is reserved for backup routes. The shortest path routing is applied in PWCE-based networks. An arrival call is accepted only when each link along the shortest path has a free working channel. Such a working path routing scheme greatly simplifies the call admission control process for dynamic traffic, and it is especially suitable for implementation in a distributed manner among network nodes. In this article, we investigate two protection strategies: Bundle Protection (BP) and Individual Protection (IDP). In BP, only one backup path can be used to protect a failure component, whereas multiple backup paths can be used in IDP. We formulate four mixed integer non-linear programming (MINLP) problems using BP and IDP strategies for single link and single node failure protection. Each model is designed to determine link metrics for shortest working path routing, working and backup channel assignments, and backup path planning. Our objective is to minimize call-blocking probability on the bottleneck link. Since these models are highly non-linear and non-convex, it is difficult to obtain exact global optimal solutions. We propose a Simulated Annealing-based Heuristic (SAH) algorithm to obtain near optimal solutions. This SAH adopts the concepts of simulated annealing as well as the bi-section technique to minimize call-blocking probabilities. To evaluate the performance, we made simulation comparisons between SAH and the unity link weight assignment scheme. The results indicate that SAH can greatly reduce call-blocking probabilities on benchmark and the randomly generated networks.

Backup path set selection in ad hoc wireless network using link expiration time

Topological changes in mobile ad hoc networks frequently render routing paths unusable. Such recurrent path failures have detrimental effects on quality of service. A suitable technique for eliminating this problem is to use multiple backup paths between the source and the destination in the network. Most of the proposed on-demand routing protocols however, build and rely on single route for each data session. Whenever there is a link disconnection on the active route, the routing protocol must perform a path recovery process. This paper proposes an effective and efficient protocol for backup and disjoint path set in an ad hoc wireless network. This protocol converges into a highly reliable path set very fast with no message exchange overhead. The paths selection according to this algorithm is beneficial for mobile ad hoc networks, since it produces a set of backup paths with much higher reliability. Simulations are conducted to evaluate the performance of our algorithm in terms of route numbers in the path set and its reliability. In order to acquire link reliability estimates, we use link expiration time (LET) between each two nodes. In another experiment, we save the LET of entire links in the ad hoc network during a specific time period, then use them as a data base for predicting the probability of proper operation of links. Links reliability obtains from LET. Prediction is done by using a multi-layer perceptron (MLP) network which is trained with error back-propagation error algorithm. Experimental results show that the MLP net can be a good choice to predict the reliability of the links between the mobile nodes with more accuracy.

Generalized Sharing in Survivable Optical Networks

Shared path protection has been demonstrated to be a very efficient survivability scheme for optical networking. In this scheme, multiple backup paths can share a given optical channel if their corresponding primary routes are not expected to fail simultaneously. The focus in this area has been the optimization of the total channels (i.e., bandwidth) provisioned in the network through the intelligent routing of primary and backup routes. In this work, we extend the current path protection sharing scheme and introduce the Generalized Sharing Concept. In this concept, we allow for additional sharing of important node devices. These node devices (e.g., optical-electronic-optical regenerators (OEOs), pure all-optical converters, etc.) constitute the dominant cost factor in an optical backbone network and the reduction of their number is of paramount importance. For demonstration purposes, we extend the concept of 1:N shared path protection to allow for the sharing of electronic regenerators needed for coping with optical transmission impairments. Both design and control plane issues are discussed through numerical examples. Considerable cost reductions in electronic budget are demonstrated

A hierarchical extension to RSVP-TE for fast lightpath setup in dynamic optical networks

This paper studies the problem of designing survivable optical wavelength division multiplexed (WDM) networks. A wavelength-routed wide area backbone network supporting circuit-switched traffic is considered. This paper also considers the use of optical wavelength conversion technology which has been shown to help improve network performance. However, wavelength conversion is still an expensive technology and using optical conversion could potentially result in signal quality degradation. In survivable networks, protection against failures is provided using backup paths that are determined when a session is established. In this paper, we present three primary and backup route computation mechanisms that attempt to improve overall network performance compared to existing solutions. One of the key design goals is to reduce the number of required converters per node. First, we present a routing algorithm, termed conversion free primary routing (CFPR) that computes primary paths without wavelength conversion, as far as possible. Next, we present a converter multiplexing technique that is used to share wavelength converters among multiple backup paths. This significantly reduces the number of connections blocked due to wavelength converter unavailability and reduces the number of wavelength converters required at each node, thus reducing system cost. Finally, we propose a backup path relocation scheme that migrates existing backup paths, whenever needed, to accommodate more primary paths and also to obtain primary routes with fewer hops. This is done to improve network utilization and reduce blocking probability. The proposed techniques are analyzed in detail using a discrete-event simulation model. The results show that significant reduction in blocking probability is possible with the proposed mechanisms. The number of converters required at each node to achieve a given blocking probability is also seen to be four times lower, compared to existing architectures based on static shortest path routing.

Cycle-Based Optical Self-Healing Network Provisioning for Resource Effciency and Robustness

In this paper, a cycle-based network recovery method for optical mesh networks is studied. The study in this paper concentrates on improving two performance requirements on network recovery: efficient spare resource utilization, and robustness for multiple failures. The proposed method uses multiple ring-covers and performs distributed link restoration using preplanned logical cycles embedded in physical mesh topologies. This method provides fast and simple recovery operation by exploiting the characteristics of ring topology and also provides efficient resource utilization by using multiple backup paths per link to improve the sharability of overall spare resources in the networks. With this method, layered reliability can be provided to network services by enabling priority-based robustness against multiple failures. The performance results reveal the trade-off between the resource efficiency for single failure and the robustness for multiple failures, and show the preconfiguration of a few logical cycles per link can provide enhanced resource efficiency and priority-based hierarchical robustness.