Routing In Wavelength Division Multiplexing Networks Research Articles

Load and Link Aware Protection Switching Technique for WDM Networks

Abstract Providing reliable connection-oriented services in wavelength division multiplexing (WDM) networks becomes challenging because of bad channel quality and overload. Most of the existing works have not considered node failures and congestion which are the essential characteristics for survivable routing. In this paper, a load and link aware protection switching technique for survivable routing in WDM networks is proposed. The technique estimates k-shortest paths for a connection request. Based on four different path possibilities, it provides the best path as connection path in terms of bandwidth. For establishing the primary path, the least virtual hop first routing algorithm is used. If the source node receives either failure or congestion warning message from the intermediate nodes, it triggers the load balanced rerouting algorithm for establishing the backup path. The proposed technique is simulated in NS-2, and the simulation results prove the efficiency of the scheme.

Ant Based Survivable Routing and Load Balancing Technique in WDM Networks

In Wavelength Division Multiplexing (WDM) networks, providing survivability during routing along with maintaining load balancing is a daunting task. In this paper, we propose an Ant based survivable routing and load balancing technique in WDM networks which discovers survivable and load balanced feasible paths. Ant agents are launched in the network to gather essential information such as available bandwidth, route length and number of free wavelengths. A combined feasibility value is generated from these factors for each path. While transmitting data to the destination, the source selects the path with high feasible value and low load as primary path, and other paths as backup paths. During congestion and failures, data transmission is redirected through the backup paths. Thus, our technique provides survivability and load balancing at hand efficiently. Simulation results show that our technique reduces packet drops efficiently by detecting and controlling the congestion.

On-line multicast routing with QoS constraints in WDM networks with no wavelength converters

The rapid growth of multicast applications initiated the need to realise multicasting in Wavelength Division Multiplexing (WDM) networks in an efficient and cost-effective way. However, most of the applications need to support dynamic multicast sessions wherein the membership of the multicast group changes with time as nodes join or leave the session dynamically. In addition, with the advancements in the multimedia and other real-time group applications, the construction of multicast trees satisfying Quality of Service (QoS) requirements of the member nodes is becoming a problem of prime importance. In this paper, we deal with on-line QoS multicast routing in WDM networks. As members leave the sessions, it will be mandatory to rearrange the trees in order to save costs, at the same time accounting for the disruption caused to the ongoing transmissions because of the rearrangement. We try to effectively decrease the disruption by considering only certain portions of the multicast tree and limiting the rearrangement to only those portions. A region's usefulness to the overall tree is judged by a novel concept of Cost-to-Service Ratio (CSR) and a region is selected for rearrangement based on its CSR value. Extensive simulation results reveal that rearrangements based on CSR can reduce the disruption to the member nodes by 20-85% compared to rearrangements based on the best known metric (Quality Factor) in the literature, for the same cost performance. We also demonstrate the cost-effectiveness of the trees generated by our on-line algorithm compared to that of static algorithm.

Maximizing Profits of Routing in WDM Networks

Let G = (V, E) be a ring (or chain) network representing an optical wavelength division multiplexing (WDM) network with k channels, where each edge e j has an integer capacity c j . A request s i ,t i is a pair of two nodes in G. Given m requests s i ,t i , i = 1, 2, ..., m, each with a profit value p i , we would like to design/route a k-colorable set of paths for some (may not be all) of the m requests such that each edge e j in G is used at most c j times and the total profit of the set of designed paths is maximized. Here two paths cannot have the same color (channel) if they share some common edge(s). This problem arises in optical communication networks. In this paper, we present a polynomial-time algorithm to solve the problem when G is a chain. When G is a ring, however, the optimization problem is NP-hard (Wan and Liu, 1998), we present a 2-approximation algorithm based on our solution to the chain network. Similarly, some results in a bidirected chain and a bidirected ring are obtained.

A lightpath allocation strategy for fair routing in WDM networks

We present a lightpath allocation strategy for fair routing in wavelength division multiplexing (WDM) optical networks without wavelength conversion. The strategy is able to yield more even pairwise blocking probabilities without much sacrificing average one. This is achieved through using alternate routing to gain network utilization and using an analytical model incorporating path‐selection criteria to systematically allocate for each source‐destination (SD) pair a set of alternate routes. In particular, the set is built with the smallest granular component lightpath in contrast to the conventional physical path consisting of a bundle of lightpaths. Additionally, the allocation exploits packing density gains by first exhausting lightpaths using a given wavelength to some extent before using another. Simulation results show that the analytical model is sufficiently accurate for identifying a target SD pair to be augmented with one more alternate lightpath, and that the proposed strategy compared with others is able to achieve significantly better uniformity of pairwise blocking probabilities even with different network parameters and topologies.

Virtual Source Based Multicast Routing in WDM Optical Networks

Wavelength-division multiplexed (WDM) networks using wavelength-routing are considered to be potential candidates for the next generation wide-area backbone networks. Multicasting is the ability to transmit information from a single source node to multiple destination nodes and is becoming an important requirement in high-speed networks. As WDM technology matures and multicast applications become increasingly popular, supporting multicast routing at the WDM layer becomes an important and yet a challenging topic. This paper concerns with the problem of optical multicast routing in WDM networks. A few nodes in the network may have wavelength conversion and/or splitting capabilities. In this paper, a new multicast tree construction algorithm is proposed. This algorithm is based on a concept called virtual source. A virtual source is a node having both the splitting and wavelength conversion capabilities. By exploiting the presence of virtual source nodes, the proposed algorithm achieves improved performance. To further improve the performance, the algorithm assigns priorities to nodes based on their capabilities. The effectiveness of the proposed algorithm is verified through extensive simulation experiments.

Constrained multicast routing in WDM networks with sparse light splitting

As wavelength division multiplexing (WDM) technology matures and multicast applications become increasingly popular, supporting multicast at the WDM layer becomes an important and yet challenging topic. In this paper, we study constrained multicast routing in WDM networks with sparse light splitting, i.e., where some switches are incapable of splitting light (of copying data in the optical domain) due to evolutional and/or economical reasons. Specifically, we propose four WDM multicast routing algorithms, namely, re-route-to-source, re-route-to-any, member-first, and member-only. Given the network topology, multicast membership information, and light splitting capability of the switches, these algorithms construct a source-based multicast "light-forest" (consisting one or more multicast trees) for each multicast session. While the first two algorithms can build on a multicast tree constructed by IP (which does not take into consideration the splitting capability of the WDM switches), the last two algorithms attempt to address the joint problem of optimal multicast routing and sparse splitting in WDM networks. The performance of these algorithms are compared in terms of the average number of wavelengths used per forest (or multicast session), average number of branches involved (bandwidth) per forest as well as average number of hops encountered (delay) from a multicast source to a multicast member. The results obtained from this research should present new and exciting opportunities for further theoretical as well as experimental work.