A novel robust routing algorithm for multi-granularity connection requests in wavelength division multiplexing mesh networks

In wavelength division multiplexing (WDM) mesh networks, wavelength utilization is limited by the mismatch between the high bandwidth that one wavelength can provide and the relatively low bandwidth request of a single connection. Traffic grooming which grooms multiple connections onto one wavelength is a desirable technique to improve resource utilization. However, with unpredictable traffic demand, the newly arrived request may not be accommodated using remaining resources. Rerouting which reroutes existing connections such that the newly arrived request can be accommodated is an effective approach to further improve network throughput. In this paper, we study adaptive intentional connection rerouting which intentionally triggers rerouting algorithm according to network status, with the aim to reserve maximum resources for future connections. There are two important issues in intentional rerouting scheme: when to trigger rerouting algorithm and the rule to reroute the accommodated connections. The answers to the questions can reduce network blocking probability within an appropriate number of rerouting. In this paper, we propose to use biological attractor selection approach to address the above issues so that rerouting can be performed at the right time to accommodate unpredictable traffic demand. The proposed rerouting scheme can also improve system robustness given its adaptability. The simulations demonstrate the effectiveness of our proposed adaptive rerouting approach.

In general, multicast routing and wavelength assignment (MC-RWA) can be subdivided in routing and wavelength assignment issues in wavelength-division multiplexing (WDM) mesh networks. Previous studies on WDM multicast have mainly focused on WDM multicast routing. The multicast wavelength assignment problem is studied in this paper. A unicast routing path can be established by a lightpath in an all-optical network. However, in the multicasting case, a multicast routing tree can be established by a single light-tree or several lightpaths, or a combination of several light-trees and lightpaths. We propose a wavelength assignment algorithm for finding an optimal combination of lightpaths and light-trees to construct a newly required multicast session. First of all, two cost functions are given to evaluate the establishing cost for each feasible wavelength, and then find a set of wavelengths that covers all destinations with the minimal cost using Integer Linear Programming (ILP) formulation. We focus on maximizing the total number of users served in a multicast session and the network capacity. The simulation results show that the proposed algorithm can improve system resource utilization and reduce the blocking probability compared with the First-Fit algorithm.

With the increasing diversity of applications supported over optical networks, new service guarantees must be offered to network customers. Among the emerging data-intensive applications are those which require their data to be transferred before a predefined deadline. We call these deadline-driven requests (DDRs). In such applications, data-transfer finish time (which must be accomplished before the deadline) is the key service guarantee that the customer wants. In fact, the amount of bandwidth allocated to transfer a request is not a concern for the customer as long as its service deadline is met. Hence, the service provider can choose the bandwidth (transmission rate) to provision the request. In this case, even though DDRs impose a deadline constraint, they provide scheduling flexibility for the service provider since it can choose the transmission rate while achieving two objectives: 1) satisfying the guaranteed deadline; and 2) optimizing the network's resource utilization. We investigate the problem of provisioning DDRs with flexible transmission rates in wavelength-division multiplexing (WDM) mesh networks, although this approach is generalizable to other networks also. We investigate several (fixed and adaptive to network state) bandwidth-allocation policies and study the benefit of allowing dynamic bandwidth adjustment, which is found to generally improve network performance. We show that the performance of the bandwidth-allocation algorithms depends on the DDR traffic distribution and on the node architecture and its parameters. In addition, we develop a mathematical formulation for our problem as a mixed integer linear program (MILP), which allows choosing flexible transmission rates and provides a lower bound for our provisioning algorithms.

We investigate waveband switching (WBS) with different grouping strategies in wavelength-division multiplexing (WDM) mesh networks. End-to-end waveband switching (ETE-WBS) and same-destination-intermediate waveband switching (SD-IT-WBS) are analyzed and compared in terms of blocking probability and cost savings. First, an analytical model for ETE-WBS is proposed to determine the network blocking probability in a mesh network. For SD-IT-WBS, a simple waveband switching algorithm is presented. An analytical model to determine the network blocking probability is proposed for SD-IT-WBS based on the algorithm. The analytical results are validated by comparing with simulation results. Both results match well and show that ETE-WBS slightly outperforms SD-IT-WBS in terms of blocking probability. On the other hand, simulation results show that SD-IT-WBS outperforms ETE-WBS in terms of cost savings.

In this paper, we investigate the problem of survivable grooming for anycasting over wavelength division multiplexing (WDM) networks. Anycasting is a communication paradigm in which a source node sends data to any one out of multiple candidate destinations. In WDM networks, the standard anycasting problem involves the establishment of a connection from the source to any one destination with the objective of minimizing the resources used. In order to provide survivability, the problem can be extended to find both a connection to a primary destination and a connection to a backup destination. The connections, which may require an amount of bandwidth that may be less than the bandwidth of an entire wavelength, can be groomed with other connections in the WDM network. We propose an auxiliary graph approach to solving the survivable grooming problem for anycasting in WDM networks, and we propose three different protection approaches for providing different degrees of survivability against link failures and destination failures. The effectiveness of the proposed schemes is verified through simulation.

In this paper, we investigate the problem of dynamically establishing dependable connections in wavelength division multiplexing (WDM) mesh networks with traffic-grooming capabilities. We first develop a new wavelength-plane graph (WPG) to represent the current state of the network. We then propose a dynamic shared sub-path protection (SSPP) scheme based on this WPG. To establish a dependable connection, SSPP first searches a primary path for each connection request, and then it segments the found path into several equal-length sub-paths, and computes their corresponding backup paths, respectively. If two sub-paths in SSPP are fiber-disjoint then their backup paths can share backup resources to obtain optimal spare capacity. Based on dynamic traffic with different load, the performance of SSPP has been investigated via simulations. The results show that SSPP can make the tradeoffs between resource utilization and restoration time.

This paper investigates the problem of dynamically establishing dependable connections in traffic-grooming wavelength division multiplexing (WDM) mesh networks, and proposes a dynamic shared sub-path protection (SSPP) scheme for multi-granularity traffic. To establish a dependable connection, SSPP searches a primary path for each connection request, and then it segments the found path into several equal-length sub-paths, and computes their corresponding backup paths, respectively. In SSPP, if two sub-paths are fiber-disjoint then their backup paths can share backup resources to obtain the optimal spare capacity. Based on dynamic traffic with different load, the performance of SSPP has been investigated via simulations. The results show that SSPP can make the tradeoffs between the resource utilization and the restoration time.

A service-level agreement (SLA) typically specifies, among other metrics, the availability a service provider (SP) promises to a customer. In an optical wavelength division multiplexing (WDM) network, connection-oriented provisioning is commonly based on whether the path's statistical availability complies with the SLA-requested availability. Because of the stochastic nature of network failures, the actually provisioned availability over a specific time period is subject to uncertainty, and hence the SLA is usually at risk. We consider this uncertainty and study provisioning to minimize SLA violations. We show that the SLA Violation Risk is affected by a number of factors (e.g., failure profiles, availability target, and penalty period), and hence cannot simply be characterized by statistical path availability. We formulate the problem of risk-aware provisioning in WDM mesh networks, where path selection is dictated by SLA Violation Risk. In particular, we focus on devising an efficient scheme capable of computing path(s) that are likely to successfully accommodate the SLA-requested availability. A novel technique is applied to convert links with heterogeneous failure profiles to reference links that capture the main risk features in a relative manner. Based on the “reference link” concept, our Risk-Aware Provisioning scheme uses only limited failure information. We also extend our Risk-Aware Provisioning to use shared-path protection (SPP) for connections with strict availability requirements. We evaluate the performance and demonstrate the effectiveness of our schemes in terms of SLA violation ratio compared to the generic availability-aware approaches.

Recent development in optical networking employing wavelength division multiplexing (WDM) fulfills the high bandwidth demand applications. Failure of such networks, leads to enormous data and revenue loss. Protection is one of the key techniques, which is used in designing survivable WDM networks. In this paper we compare dedicated and shared protection strategies employed inWDMmesh networks to protect optical networks failure, particularly fiber failure. Dijkstra’s shortest path algorithm is considered for carrying out simulations. The paper compares the performance of protection schemes, such as, dedicated path protection (DPP), shared path protection (SPP) and shared link protection (SLP) schemes. Capacity utilization, switching time and blocking probability are the parameters considered to measure the performance of the protection schemes. Simulation results show that, SPP is more efficient in terms of capacity utilization over DPP and SLP schemes, whereas, SLP offered better switching time than both DPP and SPP schemes. The average call drop rate is minimum for shared path protection scheme and maximum for shared link protection scheme.

This paper investigates the problem of dynamic shared-path-protected lightpath provisioning in optical mesh networks employing wavelength-division multiplexing (WDM). We prove that the problem of finding an eligible pair of working and backup paths for a new lightpath request requiring shared-path protection under the current network state is NP-complete. We develop a heuristic, called CAFES, to compute a feasible solution and an algorithm, called OPT, to optimize resource consumption for a given solution. The merits of our approaches are that they capture the essence of shared-path protection and approach to optimal solutions without enumerating paths. We evaluate the effectiveness of our heuristics and the results are found to be promising.

We investigate the problem of adaptive reliable multipath provisioning in next-generation backbone mesh networks employing optical wavelength-division multiplexing (WDM) and channelization techniques such as SONET/SDH, and supporting virtual concatenation (VCAT). With VCAT, a connection request can be split, diversely routed, and inversely multiplexed on to multiple paths, a feature that has many advantages over conventional single-path provisioning, such as improved reliability, load balancing, etc. However, these diversely routed traffic components are subject to the differential delay constraints (DDC), which could be limited by the destination node's delay-compensation capability, network operations, administration, maintenance, and provisioning (OAM&P), or connection quality-of-service (QoS). We introduce a new notation M : N (m) for multipath provisioning where a service path for a connection is set up with M primary paths and N backup paths, where each path may have a fraction of the bandwidth of the connection, and (m) in this notation denotes "multipath'. We present the flexibility and benefits of multipath provisioning and develop an analytical model to analyze the connection availability under M : N (m) provisioning schemes. We propose two types of bandwidth migration methods, which can be implemented by link- capacity adjustment scheme (LCAS) protocol of next-generation SONET/SDH, to optimize resource usage. We develop two adaptive heuristic algorithms to provision a connection subject to DDC while satisfying its service-level agreement (SLA). We show that, for end-to-end connection-availability-guaranteed service, multi- path provisioning can achieve better network performance than traditional single-path provisioning. With bandwidth migration, we can further improve the performance.

In wavelength-division multiplexing (WDM) optical networks, the bandwidth request of a traffic stream can be much lower than the capacity of a lightpath. Therefore, to utilize the network resources (such as bandwidth and transceivers) effectively, several low-speed traffic streams can be efficiently groomed or multiplexed into high-speed lightpaths, thus we can improve the network throughput and reduce the network cost. Traffic grooming can be considered separately at each individual node based on only local information (local grooming), or in cooperation between nodes participating in grooming (global grooming). In the second case, nodes must exchange their information about available resources and grooming strategies. The grooming problem of a static demand is considered as an optimization problem. In this work, we have proposed a traffic grooming algorithm to maximize the network throughput for wavelength-routed mesh networks. The efficiency of our approach has been established through extensive simulation on different sets of traffic demands with different bandwidth granularities for different network topologies and compared the approach with existing algorithm.

Summary form only given. We consider an arbitrary-topology, optical mesh network which employs wavelength-division multiplexing (WDM) to multiply the bandwidth on its links. Our present work is devoted to the dynamic traffic-grooming problem where connection requests (of different bandwidth granularities) arrive randomly, they need to be provisioned in real time, and to be torn down when they are over. To solve this problem, we first present five different grooming policies, e.g., whether or not to use one or more existing lightpaths to accommodate a new connection, when to set up a new lightpath, and so on. Then, we propose two distributed route-computation algorithms based on these grooming policies. Performance comparisons of these algorithms are provided for a representative example network.

In optical networks with huge transmission capability, Wavelength Division Multiplexing (WDM) has been actively studied in the research community. Traffic grooming technology based on divided bandwidth of a wavelength by WDM is very important for the network cost. This paper proposes a traffic grooming algorithm that employs the table for shortest Edge Disjoint Paths (EDPs) with clever selection on demands. Comprehensive simulations in various network environments show that the proposed algorithm outperforms well-known Maximizing Resource Utilization (MRU) up to 15% for the network throughput and up to 17% for the running time.KeywordsNetwork ThroughputNode PairConnection RequestWavelength AssignmentVirtual TopologyThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

In wavelength-division multiplexing (WDM) optical networks, the bandwidth request of a traffic stream can be much lower than the capacity of a lightpath. Efficiently grooming low-speed connections onto high-capacity lightpaths will improve the network throughput and reduce the network cost. In WDM/SONET ring networks, it has been shown in the optical network literature that by carefully grooming the low-speed connection and using wavelength-division multiplexer (OADM) to perform the optical bypass at intermediate nodes, electronic ADMs can be saved and network cost will be reduced. In this study, we investigate the traffic-grooming problem in a WDM-based optical mesh topology network. Our objective is to improve the network throughput. We study the node architecture for a WDM mesh network with traffic-grooming capability. A mathematical formulation of the traffic-grooming problem is presented in this study and several fast heuristics are also proposed and evaluated.