Failure-independent Path Protection Research Articles

Enhancement of failure independent path protection preconfigured cycles for electric power communication networks

For the purpose of improving the resources utilization efficiency and decrease network redundancy of electric power communication network (EPCN), the paper explores using failure independent path protection preconfigured cycle (FIPP p-Cycle) to provide backup paths for electric communication service and presents a protection algorithm of enhanced FIPP p-Cycle with traffic grooming (EFIPP-TG). Firstly, the multiplexing conditions of FIPP p-Cycle are analyzed specifically, and we propose a FIPP p-Cycle multiplexing algorithm to improve the utilization efficiency of backup resources. Then segment protection algorithm for working path is designed to decrease service blocking ratio as much as possible. In addition, by taking advantage of traffic grooming strategy, the routing paths of services are optimized, yielding effective decrease of network blocking probability. Simulation results from different topologies demonstrate that compared with traditional FIPP p-Cycle scheme, other p-Cycle based protection algorithms and shared backup path protection algorithm, the proposed EFIPP-TG algorithm can significantly reduce the redundancy and blocking probability of networks, shorten the length of backup path and hence improve the reliability of service and performance of network survivability.

Link failure recovery using p-cycles in wavelength division multiplex (WDM) mesh networks

Abstract Network survivability has become a crucial requirement in all types of computer networks. It becomes even more significant for wavelength division multiplex (WDM) mesh networks due to their high speed and capacity. These networks are prone to link failures. A link failure may be a single or multiple link failure. A single-link failure is easy to locate and fix as compared to multiple link failures. A dual-link failure recovery technique has been proposed using p-cycles. This technique uses a replication method for the p-cycle circle. It is an enhancement of the original failure independent path protection p-cycle scheme. The replica properties of p-cycle have been used to protect the nodes through the same p-cycle available. Creating a new p-cycle always adds to the cost of the network, whereas using a replica of already existing p-cycle significantly reduces the network cost. The proposed technique is implemented using network simulator in three phases.

Link-protection and FIPP p-cycle designs in translucent elastic optical networks

Elastic optical networks (EONs) are able to provide high spectrum utilization efficiency due to flexibility in resource assignment. In translucent EONs, by employing regenerators and using advanced modulation formats for transmission, spectrum efficiency can be further improved. Survivability is regarded as an important aspect of EONs, and p-cycle protection is considered to be an attractive scheme due to its fast restoration and high protection efficiency. In this paper, we propose methods for evaluating and selecting p-cycles for both link protection (LP) and failure-independent path protection (FIPP) to survive single-link failures. After considering the various factors that affect the performance of a p-cycle, we propose two evaluation metrics for LP and FIPP, namely, individual p-cycle cost and set of cycles cost. Based on these metrics, we propose two algorithms for selecting a set of p-cycles in translucent EONs: Traffic Independent P-cycle Selection (TIPS), which selects a set of cycles without knowledge of the traffic, and Traffic-Oriented P-cycle Selection (TOPS), which takes given traffic information into account. A routing and spectrum assignment algorithm is designed for translucent EONs, and our p-cycle design algorithms are evaluated using both static and dynamic traffic models. Simulation results show that the proposed algorithms have better performance than commonly used baseline algorithms. We also compare the performance of LP p-cycles and FIPP p-cycles.

Fast and Efficient Network Protection Method Using Path Pre-Cross-Connected Trails

This paper investigates design methods of protection schemes in survivable WDM networks using the path protection p-trail in order to provide better capacity efficiency by eliminating the rigidness of the protection structure of the well-accepted protection scheme, the failure independent path protection (FIPP) pre-configured protection cycle (p-cycle). The flexibility in the protection structure yields lower cost in terms of spare capacity allocation while maintaining the high speed of protection switching. We develop two design approaches, the fully pre-cross-connected path protection trail (fpp-trail) and the partially pre-cross-connected path protection trail (ppp-trail), based on the degree of pre-cross-connectivity of the protection structure. In order to obtain optimally designed trails, we develop an optimization model based on a large-scale optimization technique, namely, column generation. Numerical results show that fpp-trails significantly improve the spare capacity efficiency compared to the FIPP p-cycle, and ppp-trails strike a balance between capacity redundancy and recovery delay. We observe that ppp-trails can achieve as low capacity redundancy as shared backup path protection (SBPP), while the recovery delay is kept lower than in SBPP and slightly higher than FIPP p-cycles by using selective signaling through a control plane that is aware of the location of the cross-connects that are not pre-configured in advance.

P2-Cycles: p-Cycles with parasitic protection links

The p-cycle and its Failure Independent Path Protection (FIPP) extension are known to be efficient and agile protection strategies. The p-cycle is pre-configured such that if there is a failure, only the switches at two end nodes need to be reconfigured. In this paper, we extend the p-cycle by allowing cycles to have attached links, called Parasitic Protection Links (PPL), in order to protect paths whose source and destination nodes are not only located on the cycle but also connected by a PPL to the cycle. A p-cycle with PPL is named p2-cycle.We address the unicast service protection problem against single-link failures by using p2-cycle in mesh networks for both static and dynamic traffic scenarios. In the static case, the problem is formulated as an Integer Linear Program (ILP). We further propose two p2-cycle based heuristic algorithms, Strict Routing Protection (SRP) and Flexible Routing Protection (FRP), to address the dynamic traffic case. The numerical results show that the p2-cycle scheme provides better capacity efficiency than the FIPP p-cycle scheme in all the traffic scenarios considered and achieves only less than 1% extra total cost over the optimum in COST239, provided by Shared Backup Path Protection (SBPP) approach when the traffic load is high. We also study the failure recovery performance in terms of average number of switch reconfigurations (NOR), and show that the performance of the p2-cycle becomes much better than that of SBPP and gets close to FIPP as the traffic demand increases. In the dynamic case, both SRP and FRP outperform FIPP p-cycle schemes in terms of blocking probability in most scenarios considered. In general, the p2-cycle protection scheme outperforms the p-cycle based in terms of capacity efficiencies which being slightly slower in terms of traffic recovery speed.

Optimal routing with failure‐independent path protection

AbstractReliable communication has become crucial in today's information society. Modern communication networks are required to deliver reliable communication to their customers. Unfortunately, protection against network failures significantly hampers efficient utilization of network investments, because the associated routing problems become much harder. In this article we present a rigorous mathematical analysis of one of the most promising protection methods: Failure independent path protection. We present an LP model which is solved by column generation. The subproblem is proven to be strongly $ \cal N $P‐hard, but still solvable for medium sized networks through the use of specialized dynamic programming algorithms. This enables us to evaluate the performance of failure independent path protection for eight networks with up to 37 nodes and 57 links. The results indicate that only between 3% and 8% extra network capacity is necessary when compared with the capacity required by complete rerouting (which is the absolute lower bound for single link failure protection). © 2009 Wiley Periodicals, Inc. NETWORKS, 2010

Availability-Aware Design in Mesh Networks With Failure-Independent Path-Protecting $p$-Cycles

Failure-independent path-protecting (FIPP) p-cycle is an extension of the span-protecting p-cycle, and an alternative approach for providing fully pre-connected protection paths with end-to-end failure-independent path protection (Kodian and Gorver, J. of Lightwave Technol., vol. 23, no. 10, pp. 3241-3259). We study the unavailability of end-to-end traffic in FIPP-based mesh networks, which are designed to protect against single failures, and present an availability-aware network design method. Our design method allocates FIPP p -cycles such that the end-to-end unavailability of the protected demands is bounded by an upper limit which we can control. Our study will also focus on determining whether FIPP p-cycles will maintain their resource efficiency advantages over span p -cycles when the network design is based on limiting the unavailability. Our results first show that the length of the FIPP p-cycle plays a vital role in determining the availability of the working path(s). Similar to span-protecting p-cycles, higher service working path(s) availability is obtained when the FIPP p-cycle(s) contains fewer hops. Results also indicate the important role of the number of demands protected by the same FIPP p-cycle. We notice that the higher the desired availability is, the less efficient the FIPP method becomes. This relationship is due to the fact that, to achieve higher service availability, the design will limit the number of demands sharing the same FIPP cycle. Accordingly, we affirm that, when the network design limits the service unavailability, FIPP tends to be less efficient, and its redundancy is 8-13% higher than span-protecting p-cycles. Additionally, we observe that, when we do not limit the unavailability, the average availability for span-protecting p-cycles tends to be more than the FIPP p -cycle method. We present our findings.

Failure-independent path-protecting p-cycles: efficient and simple fully preconnected optical-path protection

We propose a new technique for optical-network protection called failure-independent path-protecting (FIPP) p-cycles. The method is based on an extension of p-cycle concepts to retain the property of full preconnection of protection paths, while adding the property of end-to-end failure-independent path-protection switching against either span or node failures. An issue with applying the popular method of shared-backup path protection (SBPP) to an optical network is that spare channels for the backup path must be cross connected on the fly upon failure. It takes time and signaling to make the required cross connections, but more importantly, until all connections are made, it is not actually known if the backup optical path will have adequate transmission integrity. Thus, speed and optical-path integrity are important reasons to try to have backup paths fully preconnected before failure. With fully preconnected protection, not only can very fast restoration be attained, but the optical-path engineering can also be assured prior to failure. Regular p-cycles are fully preconnected, but are not end-to-end path-protecting structures. SBPP is capacity efficient and failure independent-failures only need to be detected at the end nodes and the end nodes activate and switch over to one predefined backup route for each working path-but the backup paths are not preconnected. FIPP p-cycles support the same failure-independent end-node-activated switching of SBPP, but with the fully preconnected protection-path property of p-cycles. As a fully preconnected and path-oriented scheme, FIPP p-cycles are, therefore, potentially more attractive for optical networks than SBPP. Results confirm that FIPP p-cycle network designs will exhibit capacity efficiency that is characteristic of path-oriented schemes and may be as capacity efficient as SBPP, but more conclusive comparisons on larger scale networks await further study.