Book review: Applied cryptography: Protocols, algorithms, and source code in C

Wavelength division multiplexing (WDM) has emerged as the preferred technology for reducing the opto-electronic bandwidth mismatch by dividing the bandwidth of an optical fiber into multiple non-overlapping wavelength channels, each operating at peak electronic speed of the end users. Traffic grooming is being considered as a key functionality of WDM networks, in which, multiple low-speed traffic requests are groomed onto a single, high-capacity lightpath (wavelength). Mathematical formulation of the traffic grooming problem has been developed for various optimization objectives. The present work focuses on the traffic grooming problem in WDM mesh networks under static traffic scenario, for optimizing network revenue. We have verified ILP formulation for the problem using CPLEX 9.1 and have developed three heuristics algorithms for solving the traffic grooming problem while optimizing network revenue. Performance of the three algorithms has been evaluated and a comparative study with the results of solving the ILP model has been carried out. The algorithms have been found to give good performance, especially for larger-sized networks.

Traffic Grooming in Optical WDM Mesh Networks

Currently, wavelength division multiplexing technology is widely used for exploiting the huge bandwidth of optical networks. It allows simultaneous transmission of traffic on many nonoverlapping channels (wavelengths). These channels support traffic demands in the gigabits per second (Gb/s) range; however, since the majority of devices or applications only require a bandwidth of megabits per second (Mb/s), this is a waste of bandwidth. This problem is efficiently solved by multiplexing a number of low-speed traffic demands (Mb/s) onto a high-speed wavelength channel (Gb/s). This is known as the traffic grooming problem. Since traffic grooming is an NP-hard problem, in this paper, we propose two novel multiobjective evolutionary algorithms for solving it. The selected algorithms are multiobjective variants of the standard differential evolution (DEPT) and variable neighborhood search. With the aim of ensuring the performance of our proposals, we have made comparisons with the well-known fast Nondominated Sort Genetic Algorithm (NSGA-II), Strength Pareto Evolutionary Algorithm 2, and other approaches published in the literature. After performing diverse comparisons, we can conclude that our novel approaches obtain promising results, highlighting in particular the performance of the DEPT algorithm.

Multiobjective Metaheuristics for Traffic Grooming in Optical Networks

In wavelength routed optical networks, the number of wavelength channels is limited due to several constraints and each wavelength as well as each lightpath support traffic in the Gbps range. On the other hand, the traffic requested by an individual connection is still in the Mbps range. Therefore, to utilize the network resources (such as bandwidth and transceivers) effectively, several low-speed traffic streams have to be efficiently groomed or multiplexed into one or more high-speed lightpaths. The grooming problem of a static demand is considered as an optimization problem. In this work, we have investigated the traffic grooming problem with the objective of maximizing the network throughput for wavelength-routed mesh networks and map this problem to the clique partitioning problem. We have proposed an algorithm to handle general multi-hop static traffic grooming based on the clique partitioning concept. 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 algorithms.

Traffic grooming, routing, and wavelength assignment in an optical WDM mesh networks based on clique partitioning

Telecommunication transport networks consist of a stack of technologically different subnetworks, so-called layers, which are strongly interdependent. For example, one layer may correspond to an Internet (IP) backbone network whose links are realized by lightpath connections in an underlying optical fiber layer. To ensure that the network can fulfill its task of routing all communication requests, the inter-layer dependencies have to be taken into account already in the planning phase of the network. This is particularly important with survivability constraints, where connections in one layer have to be protected against cable cuts or equipment failures in another layer. The traditional sequential planning approach where one layer is optimized after the other cannot properly take care of the inter-layer dependencies; this can only be achieved with an integrated planning of several network layers at the same time. This thesis provides mathematical models and algorithmic techniques for the integrated optimization of two network layers with survivability constraints. We describe a multi-layer network design problem which occurs in various technologies, and model it mathematically using mixed-integer programming (MIP) formulations. The presented models cover many important practical side constraints from different technological contexts. In contrast to previous models from the literature, they can be used to design large two-layer networks with survivability requirements. We discuss modeling alternatives for various aspects of a multi-layer network and compare different routing formulations under multi-layer survivability constraints. We solve our models using a branch-and-cut-and-price approach with various problemspecific enhancements. This includes a presolving technique based on linear programming to reduce the problem size, combinatorial and sub-MIP-based primal heuristics to compute feasible network configurations, cutting planes which take the multi-layer survivability constraints into account to improve the lower bound on the optimal network cost, and column generation to generate flow variables dynamically during the algorithm. We develop techniques to speed up computations in a Benders decomposition approach and compare this approach to the standard formulation with a single MIP. We use the developed techniques to design large survivable two-layer networks by means of linear and integer programming methods. On realistic test instances with up to 67 network nodes and survivability constraints, we investigate the algorithmic impact of our techniques and show how to use them to compute good network configurations with quality guarantees. Most of the smaller test instances with up to 17 nodes can be solved to near-optimality. Moreover, we can compute feasible solutions and dual bounds even for large networks with survivability constraints, which has not been possible before.

/pdf/optimal-design-of-survivable-multi-layer-telecommunication-31xeuvck8b.pdf

Optimal Design of Survivable Multi-layer Telecommunication Networks

This paper studies a traffic grooming in wavelength-division multiplexing (WDM) mesh networks for the SONET/SDH streams requested between node pairs. The traffic could be groomed at the access node before converting to an optical signal carried in the all-optical network. We design a virtual topology with a given physical topology to satisfy multiple objectives and constraints. The grooming problem of a static demand is considered as an optimization problem. The algorithms found in the literatures focus on a single objective either to maximize the performance or to minimize the cost. We propose a multiobjective evolutionary algorithm to solve a grooming problem that optimizes multiple objectives all together at the same time. In this paper we consider the optimization of three objectives: maximize the traffic throughput, minimize the number of transceivers, and minimize the average propagation delay or average hop counts. The simulation results show that our approach is superior to an existing heuristic approaches for the 6-node benchmark network in an acceptable running time.

/pdf/an-algorithm-for-traffic-grooming-in-wdm-optical-mesh-nkwlz7bo0g.pdf

An algorithm for traffic grooming in WDM optical mesh networks with multiple objectives

This paper studies a traffic grooming in wavelength-division multiplexing (WDM) mesh networks for the SONET/SDH streams requested between node pairs. The traffic could be groomed at the access node before converting to an optical signal carried in the all-optical network. We design a virtual topology with a given physical topology to satisfy multiple objectives and constraints. The grooming problem of a static demand is considered as an optimization problem. The traditional algorithms found in the literatures mostly focus on a single objective either to maximize the performance or to minimize the cost. We propose a multi-objective evolutionary algorithm to solve a grooming problem that optimizes multiple objectives all together at the same time. In this paper we consider the optimization of three objectives: maximize the traffic throughput, minimize the number of transceivers, and minimize the average propagation delay or average hop counts. The simulation results show that our approach is superior to an existing heuristic approaches in an acceptable running time.

/pdf/an-algorithm-for-traffic-grooming-in-wdm-optical-mesh-3wzwty49nr.pdf

An Algorithm for Traffic Grooming in WDM Optical Mesh Networks with Multiple Objectives

We analyze a simple non-repudiation protocol for personal communication systems employing a one way function that establishes trust between the mobile unit and visiting location register. The security of the protocol is analyzed and a traffic analysis is performed indicating that the protocol's message overhead during call origination is tolerable to network traffic under various cell densities and traversal velocities ranging from pedestrian to vehicular speeds. The message penalty is under 15% of total control traffic for registration, origination and termination call phases at vehicular speeds with an origination rate of 5.6 calls per handset per hour. The penalty for pedestrian traffic with high origination rate is higher at 23% of total control traffic.

Analysis of a non-repudiation authentication protocol for personal communication systems

Currently public networks have an enormous number of computers capable of providing many services. Autonomous mobile agents are being used to access their information sources. These agents are modeled in the context of network simulation as mobile network processes. The paper demonstrates that distributed mobile agents can be simulated effectively using C++ over CSIM. C++ over CSIM achieves the clarity and logic of agent based simulation for network services. Inheritance and specialization under object orientation allow the design and reuse of simulation objects. This combination facilitates rather straightforward simulation designs that are scalable, accurate, flexible and generalizable. The design for such large scale simulation is sketched and the run time behavior of the simulator is analyzed.

Simulating agent based processing in an ADS using C++ SIM

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An algorithm for traffic grooming in WDM optical mesh networks with multiple objectives

An Algorithm for Traffic Grooming in WDM Optical Mesh Networks with Multiple Objectives

Analysis of a non-repudiation authentication protocol for personal communication systems

Simulating agent based processing in an ADS using C++ SIM