End-to-end signaling and routing for optical IP networks

A key means for improving service availability in optical networks is the ability to recover from dual near-simultaneous failures. To date, most studies have focused on improving survivability for single failure events either via proactive or reactive mechanisms. Conversely, lightpath re-provisioning has only recently been considered as an alternative for improving overall network restorability in the event of dual failures. Here, post-failure re-provisioning establishes new backup capacities for connections in advance of a second failure. In this paper we propose a new re-provisioning algorithm to improve the restorability of shared optical networks and compare its performance with a conventional scheme. Namely, the proposed algorithm only requires re-provisioning of a fraction of connections, since upon re-routing onto shared backup capacity, some connections are only in a temporarily unprotected state. Through simulation analysis, we demonstrate the effectiveness of the proposed approach in improving optical network restorability with and without wavelength conversion.

GMPLS grew out of MPLS, a packet-switching technology designed to improve the efficiency of data networks. In this paper, we discuss the GMPLS technology, analyze its application. GMPLS is an advanced protocol which is essential for managing a diverse and complex network, because service deployment and service provisioning are manual, lengthy and costly processes. GMPLS has caused technical challenges in its deployment in optical networks. These challenges can be generalized into two areas: label assignment and wavelength conversion capability. In regard to wavelength conversion, which is correlated to routing problems. The inability of the optical switch to perform wavelength conversion has yielded a routing problem. The incompatibility of optical devices has violated the algorithms of path determination. It results in a high blocking factor call a long the path and high latency; these would eventually prejudice the performance of optical networks.

In this paper, we analyze the optical network with wavelength conversion, and discuss the architecture of network with wavelength converter in its node. The optical cross connects technology for wavelength division multiplexing (WDM) is rapidly developing. Wavelength conversion is one of the key techniques for switch WDM optical networks. The wavelength conversion technology can achieve wavelength reuse, decrease wavelength competition, enhance network flexibility and scalability, and simplify network structure and management. The results show that If these cross-connectors feature integrated with wavelength conversion, network will be better able to play the full potential of WDM optical networks.

In optical burst switching networks, wavelength converters (WCs) of core nodes are used to decrease the burst loss rate. The implementation of the WCs is difficult in the current technology and the cost of WCs is high. So some core nodes may be configured insufficient WCs to reduce the cost in OBS networks. However, many data channel scheduling algorithms do not count the number of WCs and the performance of burst loss rate is not good in the condition of insufficient WCs. To overcome the defect, two novel batch scheduling algorithm with insufficiency of WC are proposed in this paper. The former algorithm improves the WCs’ resource utilization probability to reduce the burst loss rate and the later algorithm saves the WCs’ resource for the incoming bursts to use to improve the burst loss performance. The later algorithm can reduce more burst loss rate with the same number of WCs, compared with the other scheduling algorithms. The simulation results show that the later algorithm is more effective in reducing the burst loss rate with insufficient WCs.

Recently, machine learning (ML) has attracted the attention of both researchers and practitioners to address several issues in the optical networking field. This trend has been mainly driven by the huge amount of available data (i.e., signal quality indicators, network alarms, etc.) and to the large number of optimization parameters which feature current optical networks (such as, modulation format, lightpath routes, transport wavelength, etc.). In this paper, we leverage the techniques from the ML discipline to efficiently accomplish the routing and wavelength assignment (RWA) for an input traffic matrix in an optical WDM network. Numerical results show that near-optimal RWA can be obtained with our approach, while reducing computational time up to 93% in comparison to a traditional optimization approach based on integer linear programming. Moreover, to further demonstrate the effectiveness of our approach, we deployed the ML classifier into an ONOS-based software defined optical network laboratory testbed, where we evaluate the performance of the overall RWA process in terms of computational time.

In all-optical Wavelength Division Multiplexing (WDM) technique, data contention is an inevitable challenge. For reliable data transmission, contention resolution is very much essential. There are different contention resolution techniques that are used in optical WDM network. In this paper, wavelength converter is used for contention resolution in optical WDM network. Here Semiconductor Optical Amplifier (SOA) is used to implement wavelength converter based on a special third-order nonlinear susceptibility phenomenon of silica fiber, called Four-Wave Mixing (FWM) technique. Realization of wavelength converter is done for two different sets of WDM networks. Performance of the wavelength converter was estimated in terms of number frequencies generated, number of new wavelength generated, its corresponding power, etc. Result shows that four-wave mixing is a very effective technique to generate new wavelengths at the output to overcome the problems due to contention in an optical WDM network. OptiSystem of Optiwave is used to design schematic layout for the wavelength converter using SOA.

This paper describes the advantages introduced by wavelength conversion in the design, implementation and management of future WDM optical networks and nodes. We describe the routing and wavelength assignment process in a WDM network and then we will demonstrate the major advantages introduced by wavelength conversion, mainly regarding the dimensioning aspects but also including considerations on the physical and management issues.

We propose a hierarchical optical path network design algorithm that considers wavelength conversion. Numerical experiments prove that, by employing wavelength conversion, hierarchical optical path networks will be more cost effective than single-layer optical path networks over a wide range of traffic demand, which is not possible without using wavelength conversion.

OFs (Optical Fibers) are broadly used for information broadcast systems due to their extensive information-carrying capability and dielectric environment. The OFs network architectures that use several WLs (wavelengths) per OFs connect thousands of users in central, urban, or large-scale applications with a wide range of transmission speeds and capabilities. This article defines a detailed introduction to optical fiber networks and general phases of communication of OF (Optical Fiber) procedure. The taxonomy may be based on optical fibers such as; (i) Structure, (ii) number of modes, (iii) refractive index profile, (iv) dispersion, (v) signal processing capacity (vi) Polarization. After that, it explains the merits and demerits of optical fiber networks. They studied optical wireless communications applications such as SMs (shopping malls), UW (underwater), industries, etc. Several analyses with different optimization methods such as Genetic Algorithm (GA), Ant Colony Optimization (ACO), and Particle-Swarm Optimization (PSO) algorithms. An effective resource-allocation method is required to reduce the issue of EE (energy-efficiency) and improve the presentation of quality-of-services of the ONs (Optical Networks).

A novel dynamic survivable routing in WDM optical networks with/without sparse wavelength conversion

In wavelength division multiplexed all optical networks; lightpath establishes a connection between sending and receiving nodes bypassing the electronic processing at intermediate nodes. One of the prime objectives of Routing and Wavelength Assignment (RWA) problem is to maximize the number of connections efficiently by choosing the best routes. Although there are several algorithms available, improving the blocking performance in optical networks and finding optimal solutions for RWA problem has still remained a challenging issue. Wavelength conversion can be helpful in restricting the problem of wavelength continuity constraint but it increases complexity in the network. In this paper, we propose new weight dependent routing and wavelength assignment strategy for all optical networks without use of wavelength converters. Proposed weight function reduces blocking probability significantly, improving the network performance at various load conditions. Further, due to absence of wavelength converters, the cost and complexity of network reduces. Results show that the proposed strategy performs better than earlier reported methods.

In this paper we consider the routing and wavelength assignment problem in a wavelength routed all optical network. Inspired by techniques from artificial intelligence, in particular the Blocking Island (BI) abstraction, we propose a simple and intelligent routing and wavelength assignment (RWA) algorithm: BI_RWA. This algorithm can be used in arbitrarily connected optical networks. In addition, it is general enough such that with some simple modifications, it can be applied to different optical networking scenarios: static or dynamic traffic, single or multiple fiber links between node pairs, with or without wavelength converters. We have conducted simulation experiments to evaluate the performance of our algorithm. The simulation is carried out in two parts: static traffic and dynamic traffic. The results will demonstrate that our RWA algorithm outperforms state-of-the-art related algorithms.

We study the problem of allocating optical bandwidth to sets of communication requests in all–optical networks that utilize Wavelength Division Multiplexing (WDM). WDM technology establishes communication between pairs of network nodes by establishing transmitter–receiver paths and assigning wavelengths to each path so that no two paths going through the same fiber link use the same wavelength. Optical bandwidth is the number of distinct wavelengths. Since state–of–the–art technology allows for a limited number of wavelengths, the engineering problem to be solved is to establish communication between pairs of nodes so that the total number of wavelengths used is minimized; this is known as the wavelength routing problem. In this paper we survey recent advances in bandwidth allocation in tree–shaped WDM all–optical networks. We present hardness results and lower bounds for the general problem and the special case of symmetric communication. We give the main ideas of deterministic greedy algorithms and study their limitations. We demonstrate how we can achieve optimal and nearly–optimal bandwidth utilization in networks with wavelength converters using simple algorithms. We also present recent results about the use of randomization for wavelength routing.

Both access and core optical networks require connectivity between a given set of pairs of nodes under path-length constraints. In the context of Long Reach Passive Optical Networks (LR-PON) there is a limit on the length of the fibre between a local-exchange (LE) site and its metro-core (MC) node, and in the transparent optical core network the length of fibre between each pair of MC nodes must be within a given threshold. A failure in the network could affect hundreds of thousands of customers. Therefore, it is often important ensuring multiple connectivity between a given set of pair of nodes through at least two node-disjoint paths while respecting the path-length constraints. Node-disjointness allows switching to an alternative path whenever a link or a node fails. Minimising the cost associated with the fibre while maximising the disjointness for a given network is a very challenging task. In this paper, we develop and present a general approach that is scalable for solving very large instances of this problem.

Wave length division multiplexing has emerged as a promising technology for backbone networks. The optical layer based on WDM technology provides optical routing services to the upper layers. We consider large optical networks in which nodes employ wavelength-routing switches and wavelength converters which enable the establishment of wavelength-division multiplexed channels called light paths, between node pairs. We propose a algorithm called modified DORA which solves the routing and wavelength assignment of light paths in such networks. We studied the performance of proposed algorithm for a standard NSFNET for 10 nodes and 15 links and analyzed the blocking probability for various cases. We studied the dynamic routing algorithm. We modified the algorithm to suit for WDM networks. We compare it with the exhaust routing in terms of blocking probability, channel utilization and complexity