Survivable Optical Networks Research Articles

Power consumption reduction through elastic data rate adaptation in survivable multi-layer optical networks

Network survivability requires the provisioning of backup resources in order to protect active traffic against any failure scenario. Backup resources, however, can remain unused most of the time while the network is not in failure condition, inducing high power consumption wastage, if fully powered on. In this paper, we highlight the power consumption wastage of the additional resources for survivability in IP/multi-protocol label switching (MPLS) over dense wavelength division multiplexing multi-layer optical networks. We assume MPLS protection switching as the failure recovery mechanism in the network, a solution interesting for current network operators to ensure fast recovery as well as fine-grained recovery treatment per label switched path. Next, we quantitatively show how elastic optical technologies can effectively reduce such a power consumption by dynamically adjusting the data rate of the transponders to the carried amount of traffic.

Green multicast grooming based on cross-shared protection in optical WDM networks

Currently, multicast survivability in optical network obtains more attention. This paper focuses on the field of multicast grooming shared protection in green optical network and designs a novel auxiliary graph and a shared matrix to address the survivable multicast resource consumption. This paper also proposes a new heuristic called Green Multicast Grooming algorithm based on spanning path Cross-Shared protection (GMG-CSP), in which network reliability, energy efficiency and resource utilization are jointly considered. Simulation results testify that, compared to other algorithms, the proposed GMG-CSP not only has lower blocking probability and higher bandwidth utilization ratio, but also saves more energy.

Joint Design on DCN Placement and Survivable Cloud Service Provision over All-Optical Mesh Networks

Cloud services based on data center networks (DCNs) require a transmission infrastructure with high-capacity, low-latency, low-cost and high-availability, which can be offered by survivable optical networks. DCN placement is a fundamental issue in supporting cloud services in optical networks. It concerns not only the cost of providing cloud services, but also the service availability against failures via proper service replicas. In this paper, we jointly optimize DCN placement with service routing and protection to minimize the network cost, while ensuring fast protection of all services against any single link failure or service failure at a particular DCN. An ILP (Integer Linear Program) is first formulated to achieve optimal joint design. It integrates p-cycle (preconfigured protection cycle) for fast protection against a single link failure, and DCN replicas and fast service rerouting against a service failure. To make the design more scalable, a two-step heuristic is then proposed for large-size network scenarios. The first step separately solves the DCN placement and service routing problem in the failure-free scenario, and the second step takes fast service protection into account. The proposed design is validated by extensive numerical experiments.

可生存LR-PON中基于连接可用性的成本有效规划方法

可生存LR-PON中基于连接可用性的成本有效规划方法

Survivable routing and wavelength assignment performance improvement using primary-backup multiplexing with 100% fault recovery guarantee

In this paper, we address the problem of designing survivable optical networks. Path Protection (PP) and Link Protection (LP) schemes are the main means of protecting Wavelength-Division Multiplexed (WDM) networks from the losses caused by a component failure. We here propose to use a new generalization of the PP scheme called Partial Path Protection (PPP). PPP designates a different restoration path for every link failure of every primary path. Based on the PPP scheme, an Integer Linear Programming (ILP) model and a heuristic algorithm are presented to tackle the problem of establishing a set of static connections, referred to as Dependable connections (D-connections), with fault-tolerant requirements under Shared Risk Link Group (SRLG) constraints. Both approaches aim at maximizing the overall network throughput by minimizing the total bandwidth consumption using two resource sharing techniques, namely Primary-Backup Multiplexing (PBM) and Backup-Backup Multiplexing (BBM). To the best of our knowledge, this is the first attempt to combine these two techniques when routing static D-connections and performed in such a way that 100% fault-recovery is still guaranteed for all established connections. Multiple simulation studies have been carried out on different network topologies to evaluate the performance of the proposed solutions. These performance results are also compared to those of previously proposed approaches in the literature, to outline the improvements brought by our approaches.

Computing blocking probabilities in survivable WDM optical networks

One of the most important performance measurements in wavelength-division multiplexing (WDM) networks is the call blocking probability. In this paper, we present an approximate analytical method to evaluate the blocking probabilities in survivable WDM networks with dynamically arriving connection requests. Our approach utilizes the wavelength independence whereby WDM network can be regarded as an aggregation of disjoint single wavelength sub-networks with a common physical topology. In each single wavelength sub-network, we derive the calculation of the blocking probability from an exact analysis. We assume dedicated protection with fixed routing and either first-fit or random wavelength assignment. Simulation results demonstrate the accuracy of the proposed method.

A new green multicast grooming protection algorithm in WDM optical networks

Since optical network carries a lot of traffic, survivability is very important to ensure the service continuity against network failures. Recently, multicast services become more popular to meet the huge multimedia demand in network, so that multicast survivability in optical network has got more attention. However, multicast survivability may lead to more energy consumption due to more redundant backup resources allocated. Since greening network is particularly important with the energy crisis keeping growing, green multicast survivability in optical network is a challenging issue. This paper focuses on the green multicast grooming protection problem in optical network and designs two auxiliary graphs that includes a virtual topology graph and an integrated graph to address the survivable multicast grooming, routing and wavelength assignment. Based on the auxiliary graphs, this paper proposes an efficient heuristic called green multicast grooming algorithm based on spanning path dedicated protection (GMG-SPDP), in which the network reliability and the energy efficiency are jointly taken into account. Simulation results show that, compared to other algorithms, the proposed GMG-SPDP not only has lower blocking probability and higher bandwidth utilization ratio, but also saves more energy.

Survivable wavelength-division multiplexing passive optical network system with centralized protection routing scheme and efficient wavelength utilization

A survivable wavelength-division multiplexing passive optical network (WDM-PON) with centralized protection scheme and colorless optical network units is proposed. The sideband channels generated via optical carrier suppression technique are used to carry both the downstream (DS) and the upstream (US) remodulated signals for two neighboring sub-PONs. By employing alternate path routing of sideband channels, the centralized protection scheme can provide reliable protection against any failure in feed fibers, remote node, and distribution fibers. The number of extra fibers is greatly reduced, and efficient utilization of wavelength resource is achieved. The feasibility of the proposed system is verified by 10-Gb/s DS and 1.25-Gb/s US signals over 25-km single-mode fiber transmission in both working and protection modes.

Methods for physical impairment constrained routing with selected protection in all-optical networks

In this paper, we investigate the problem of survivable all-optical routing in WDM networks with physical impairments. One of the recent key issues in survivable optical network design refers to maximization of the ratio of routeable demands while keeping the overall network cost low. In WDM networks, this goal can be achieved by routing as many demands in all-optical way as possible. Based on the latest technical trends driven by deployment costs, technical constraints, and backward compatibility, this will not mean that all demands will be routed in all-optical way in the near future.Nowadays, operators are mostly willing to dedicate only a given ratio of their power budget to all-optical routing. This in turn implies a new problem to be solved: operators have to find a way to select demands that should be routed in all-optical way and which should not. The problem gets even more complicated, if we add demand protection issues.In this paper, we introduce and evaluate methods able to maximize the number of demands routed with protection in all-optical way in capacity-constrained networks with limitations on path lengths according to physical impairments.

Disaster survivability in optical communication networks

With the frequent occurrences of natural disasters damaging large portions of communication networks and the rising risk of intentional attacks, network vulnerability to multiple cascading, correlated, and collocated failures has become a major concern. Optical backbone networks provide highly-scalable connectivity across large distances. These networks exploit optical technology to carry huge aggregated data and can support “higher-layer” networks, such as SONET, Ethernet, IP, MPLS, ATM, etc. Given the high complexity and scale of backbone networks, multiple correlated failures can have a devastating impact on topological connectivity, which in turn can cause widespread “end-to-end” connection-level disruptions. These outages may affect many applications/services supported by the optical layer, irrespective of the importance of the service and/or sensitivity of the carried data. Hence, it is crucial to understand the vulnerability of optical backbone networks to disasters and design appropriate countermeasures. In this paper, we present a general classification of the existing research works on disaster survivability in optical networks and a survey on relevant works based on that classification. We also classify disasters based on their characteristics and impact on communication networks and discuss different ways to combat them. We conclude the paper with open issues and challenges.

Role of Edge Connectivity and Centrality Factors in Survivable Optical Network Design

Role of Edge Connectivity and Centrality Factors in Survivable Optical Network Design

On Exploiting Sharable Resources With Resource Contention Resolution for Surviving Double-Link Failures in Optical Mesh Networks

As the size and the complexity of optical mesh networks grow, double-link failures become more probable. To protect against double-link failures, we generally have to provision more backup resources with respect to single-link failures. To improve the resource efficiency, it is important to reduce backup resources used for surviving double-link failures. In this paper, we investigate some representative sharing schemes and propose an enhanced resource sharing scheme with resource contention resolution for double-link failures in survivable optical mesh networks. By fully taking into account the temporal and spatial factors, our scheme can accommodate reasonable contention for sharing resources and minimize backup resources for reservation with 100% protection guarantee. Simulation results show that this enhanced resource sharing scheme can achieve satisfactory performance in terms of resource utilization ratio and blocking probability.

Inter group shared protection (I-GSP) for survivable WDM mesh networks

This paper focuses on the survivable routing problem in WDM mesh networks where the objective is to minimize the total number of wavelengths used for establishing working and protection paths in the WDM networks. The past studies for survivable routing suffers from the scalability problem when the number of nodes/links or connection requests grows in the network. In this paper, a novel path-based shared protection framework, namely inter group shared protection (I-GSP), is proposed where the traffic matrix can be divided into multiple protection groups (PGs) based on specific grouping policy. Optimization is performed on these PGs such that sharing of protection wavelengths is considered not only inside a PG, but between the PGs. Simulation results show that I-GSP based integer linear programming model, namely, ILP-II solves the networks in a reasonable amount of time for which a regular integer linear programming formulation, namely, ILP-I becomes computationally intractable. For most of the cases the gap between the optimal solution and the ILP-II stays within 6%. The proposed ILP-II model yields a scalable solution for the capacity planning in the survivable optical networks based on the proposed I-GSP protection architecture.

Holding time aware differentiated protection method for survivable waveband switching optical networks

Due to the number of wavelengths in fibers increasing, the transmission ports consumed in optical cross-connect (OXC) are greatly enhanced. To reduce the complexity and the cost of OXC, waveband switching technology is proposed. At the same time, since an optical channel carries a lot of traffic, its failure may lead to a huge data loss. Therefore, survivability in waveband switching (WBS) optical networks is important. Previous work for survivable WBS optical networks did not consider the holding time of connection request. However, in a practical network, the different connection requests generally have different holding times. This fact affects the network performances. In this paper, we propose a new method, holding time aware differentiated protection (HTADP), to provide the survivability for single-link failure in WBS optical networks. In HTADP, if the holding time of a connection request is smaller than the preset threshold, the protection path will not be assigned for saving network resources. In addition, we design a waveband integrated auxiliary graph for HTADP to well support the routing and waveband assignment. Simulation results demonstrate that HTADP not only saves more transmission ports but also is able to obtain lower blocking probability compared with previous method.

A Survivable Wavelength Division Multiplexing Passive Optical Network with Both Point-to-Point Service and Broadcast Service Delivery

A survivable wavelength division multiplexing passive optical network enabling both point-to-point service and broadcast service is presented and demonstrated. This architecture provides an automatic traffic recovery against feeder and distribution fiber link failure, respectively. In addition, it also simplifies the protection design for multiple services transmission in wavelength division multiplexing passive optical networks.

Simultaneous optimization of unicast and anycast flows and replica location in survivable optical networks

Most of previous works related to survivable networks have been focused on unicast communications. In this paper, we address the problem of network survivability in the context of anycast communications, which has not attracted much attention recently. Anycast transmission is defined as one-to-one-of-many. To assure the network survivability, we use the single backup path approach, i.e., each demand has two node-disjoint paths to provide protection against a single link failure. We formulate new ILP models to find the optimal paths for anycast and unicast connections, as well as to find the optimal location of replica servers. To test the proposed approach, we run extensive numerical experiments using CPLEX solver on four example network topologies with different scenarios of replica server count and the proportion between unicast and anycast traffic. Results prove the efficiency of our solution in terms of various parameters including cost, path length, resource utilization, and time of computation.

Research on the Capability of Survivability in Optical Network

Survivability is the capability of a network to maintain service continuity in the presence of faults within the network. In this paper, we presented the new survivability method and discussed the capability of survivability in optical network. The survivability in WDM networks is implemented using protectionand restorationtechniques. Protection is a static mechanism to protect against failure, where the resource for both the primary and the backup light-paths are reserved prior to the data communication. Restoration on the other hand, is a dynamic mechanism where the backup light-path is not set up until the failure occurs. Survivability using these techniques is usually provided to handle single link failures in the core network.

P-Cycle protection at the glass fiber level

The cost and complexity of wavelength assignment, wavelength conversion and wavelength-selective switching are always of primary considerations in the design of survivable optical networks. This proposal recognizes that as long as the loss budgets are adequate, entire DWDM wavebands could be restored with no switching or manipulation of individual lightpaths; so that the DWDM layer would never know the break happened. And environments where fiber switching devices are low cost, and ducts are full of dark fibers provide a very low cost alternative to protect an entire DWDM transport layer (or working capacity envelope) against the single largest cause of outage. Yet, while nodes and single DWDM channels may fail, a pre-dominant source of unavailability is the physical damage of optical cables. Thus, with the objectives of reducing the overall real CapEx costs and removing the complexity due to wavelength assignment and wavelength continuity constraints when configuring p-cycles in a fully transparent network context, this paper addresses the subsequent questions: if it is ultimately glass that fails, what if just the glass is directly replaced? More specifically, what if p-cycles were used to rapidly, simply and efficiently provide for the direct replacement of failed fiber sections with whole replacement fibers?

Genetic Algorithm for the Topological Design of Survivable Optical Transport Networks

We develop a genetic algorithm for the topological design of survivable optical transport networks with minimum capital expenditure. Using the developed genetic algorithm we can obtain near-optimal topologies in a short time. The quality of the obtained solutions is assessed using an integer linear programming model. Two initial population generators, two selection methods, two crossover operators, and two population sizes are analyzed. Computational results obtained using real telecommunications networks show that by using an initial population that resembles real optical transport networks a good convergence is achieved.

Multi-links recovery algorithm in survivable WDM optical network

A new survivable algorithm called Self-organizing Shared-Path Protection (SSPP) is proposed to tolerate multi-link failures in wavelength division multiplexing optical networks. In SSPP, ant agents are used to search primary paths, and load balancing is considered in this approach to reduce blocking probability (BP). In the approach of search backup paths, different backup path ant agents use a same kind pheromone and these ant agents are attracted by each other, so different backup paths share more backup resources. In order to tolerate multi-link failures, self-organizing ant agents search new routes for carrying the traffic affected by the failures. Simulation results show that compared with other algorithms, SSPP has lower BP, better resource utilization ratio, and higher protection ability.