Increasing resilience of ATM networks using traffic monitoring and automated anomaly analysis

Systematic network monitoring can be the cornerstone for the dependable operation of safety-critical distributed systems. In this paper, we present our vision for informed anomaly detection through network monitoring and resilience measurements to increase the operators' visibility of ATM communication networks. We raise the question of how to determine the optimal level of automation in this safety-critical context, and we present a novel passive network monitoring system that can reveal network utilisation trends and traffic patterns in diverse timescales. Using network measurements, we derive resilience metrics and visualisations to enhance the operators' knowledge of the network and traffic behaviour, and allow for network planning and provisioning based on informed what-if analysis

Risk based resilient network design

This paper presents a risk-based approach to resilient network design. The basic design problem considered is that given a working network and a fixed budget, how best to allocate the budget for deploying a survivability technique in different parts of the network based on managing the risk. The term risk measures two related quantities: the likelihood of failure or attack, and the amount of damage caused by the failure or attack. Various designs with different risk-based design objectives are considered, for example, minimizing the expected damage, minimizing the maximum damage, and minimizing a measure of the variability of damage that could occur in the network. A design methodology for the proposed risk-based survivable network design approach is presented within an optimization model framework. Numerical results and analysis illustrating the different risk based designs and the tradeoffs among the schemes are presented. © 2011 Springer Science+Business Media, LLC

Design of survivable wavelength division multiplexed passive optical networks.

by Chan Tsan Jim.Thesis (M.Phil.)--Chinese University of Hong Kong, 2003.Includes bibliographical references (leaves 68-71).Abstracts in English and Chinese.Chapter Chapter 1 --- Introduction --- p.1Chapter 1.1 --- Introduction --- p.1Chapter 1.2 --- Background --- p.2Chapter 1.2.1 --- Introduction --- p.2Chapter 1.2.2 --- Wavelength Division Multiplexing --- p.3Chapter 1.2.3 --- Arrayed Waveguide Grating --- p.5Chapter 1.2.4 --- Passive Optical Networks --- p.7Chapter 1.3 --- Outline of the thesis --- p.10Chapter Chapter 2 --- Review of Protection and Restoration Schemes --- p.12Chapter 2.1 --- Introduction --- p.12Chapter 2.2 --- Protection Schemes --- p.14Chapter 2.2.1 --- Path Protection --- p.14Chapter 2.2.2 --- Link Protection --- p.16Chapter 2.3 --- Restoration Schemes --- p.17Chapter 2.3.1 --- Path Restoration --- p.17Chapter 2.3.2 --- Link Restoration --- p.18Chapter 2.4 --- Protection and Restoration Schemes in PON --- p.18Chapter 2.4.1 --- Protection Schemes in G.983.1 --- p.18Chapter 2.4.2 --- Other Proposed Schemes --- p.21Chapter Chapter 3 --- Design of WDM PON Network Architecture --- p.26Chapter 3.1 --- Introduction --- p.26Chapter 3.2 --- The Group Protection Architecture (GPA) --- p.27Chapter 3.2.1 --- Network Design --- p.27Chapter 3.2.2 --- Protection Mechanism --- p.28Chapter 3.2.3 --- Wavelength Assignments --- p.30Chapter 3.2.4 --- Power Budget Calculation --- p.32Chapter 3.2.5 --- Crosstalk Analysis --- p.33Chapter 3.2.6 --- Discussion --- p.35Chapter 3.3 --- The Enhanced Group Protection Architecture (EGPA) --- p.36Chapter 3.3.1 --- Introduction --- p.36Chapter 3.3.2 --- Network Design --- p.37Chapter 3.3.3 --- Protection Mechanism --- p.38Chapter 3.3.4 --- Wavelength Assignments --- p.39Chapter 3.3.5 --- Power Budget Calculation --- p.40Chapter 3.3.6 --- Crosstalk Analysis --- p.41Chapter 3.3.7 --- Discussion --- p.42Chapter 3.4 --- The Hybrid Ring Architecture (HR) --- p.42Chapter 3.4.1 --- Introduction --- p.42Chapter 3.4.2 --- Network Design --- p.43Chapter 3.4.3 --- Protection Mechanism --- p.44Chapter 3.4.4 --- Wavelength Assignments --- p.45Chapter 3.4.5 --- Power Budget Calculation --- p.46Chapter 3.4.6 --- Crosstalk Analysis --- p.47Chapter 3.4.7 --- Discussion --- p.47Chapter 3.5 --- Comparison of the three schemes --- p.48Chapter 3.6 --- Summary of the three schemes --- p.50Chapter Chapter 4 --- Experimental Evaluation --- p.51Chapter 4.1 --- Introduction --- p.51Chapter 4.2 --- Experimental Setup --- p.51Chapter 4.2.1 --- The GPA Scheme --- p.51Chapter 4.2.2 --- The EGPA Scheme --- p.53Chapter 4.2.3 --- The HR Scheme --- p.54Chapter 4.3 --- Experimental Result --- p.55Chapter 4.3.1 --- Optical Spectrum --- p.55Chapter 4.3.2 --- Transmission Performance --- p.58Chapter 4.3.3 --- Switching/Restoration Time --- p.61Chapter 4.3.4 --- Crosstalk Penalty --- p.63Chapter 4.4 --- Conclusion --- p.64Chapter Chapter 5 --- Conclusion and Future Works --- p.65Chapter 5.1 --- Introduction --- p.65Chapter 5.2 --- Conclusion --- p.65Chapter 5.3 --- Future Works --- p.66References --- p.6

Availability-Aware Spare Capacity Allocation with Partially Protected Rings

This thesis work focuses on designing a survivable IP-core network with the minimal investment of spare capacity. A span-oriented spare capacity allocation (SCA) scheme is proposed to satisfy customers' availability requirements in the end-to-end (E2E) sense. The novelty of the proposed SCA scheme is that it meets the E2E availability requirements despite the lack of knowledge of E2E bandwidth by employing protection rings covering all links in the network. Different ring selection methods are presented and also compared from the aspect of network redundancy and LP feasibility which provide more flexibility to the design. The proposed SCA algorithm further minimizes total cost of spare capacity by incorporating partial protection within the proposed architecture. The simulation results show that it can significantly reduce the spare capacity consumption depending on the availability. The proposed SCA scheme also performs better in terms of redundancy than that of two other dominant methods available these days

A tabu search algorithm for dynamic routing in ATM cell-switching networks

This paper deals with the dynamic routing problem in ATM cell-switching networks. We present a mathematical programming model based on cell loss and a Tabu Search algorithm with short-term memory that is reinforced with a long-term memory procedure. The estimation of the quality of the solutions is fast, due to the specific encoding of the feasible solutions. The Tabu Search algorithm reaches good quality solutions, outperforming other approaches such as Genetic Algorithms and the Minimum Switching Path heuristic, regarding both cell loss and the CPU time consumption. The best results were found for the more complex networks with a high number of switches and links

User services of tactical communications in the digital age, Journal of Telecommunications and Information Technology, 2004, nr 4

Increasing demands on an extensive amount of digital data and information flows for C4I is forcing the modern armies to freeze and omit EUROCOM based tactical area communications system and to develop new concepts based on the adoption of modern communication systems such as ISDN, ATM described in the TACOMS Post 2000 Final Report II in NATO. ASELSAN, as a leading company in the military electronics arena, is following and participating all the activities of TACOMS Post 2000 together with Turkish Ministry of Defense. Turkey's tactical area communications system TASMUS is a mature and fielded system, which will satisfy future communication needs of the 21st century C4I systems. In this paper, we describe the basic features and user services of TASMUS. With the support of simultaneous voice and data capabilities, TASMUS aims to form mobile, survivable, flexible and secure network to support all the present and future communication requirements of the tactical commanders. Using the near real time data communications feature, TASMUS is also significant for the network-centric warfare applications such as tactical sensor and weapon systems, besides the communication needs of the Turkish Army

Performance Analysis and Design of Mobile Ad-Hoc Networks

We focus on the performance analysis and design of a wireless ad-hoc network using a virtual-circuit or reservation based medium access layer. In a reservation based MAC network, source nodes reserve a session's link capacity end-to-end over the entire path before sending traffic over the established path. An example of a generic reservation based MAC protocol is Unifying Slot Assignment Protocol (USAP). Any reservation based medium access protocol (including USAP) uses a simple set of rules to determine the cells or timeslots available at a node to reserve link capacity along the path to the next node. Given inputs of node locations, traffic pattern between nodes and link propagation matrices, we develop models to estimate blocking probability and throughput for reservation based wireless ad-hoc networks. These models are based on extending reduced load loss network models for a wireless network. For generic USAP with multiple frequency channels, the key effect of multiuser interference on a link is modeled via reduced available link capacity where the effects of transmissions and receptions in the link neighborhood are modeled using USAP reservation rules. We compare our results with simulation and obtain good results using our extended reduced load loss network models but with reduced available link capacity distribution obtained by simulation. For the case of generic USAP using a single frequency channel, we develop models for unicast traffic using reduced load loss network models but with the sharing of the wireless medium between a node and its neighbors modeled by considering cliques of neighboring interfering links around a particular link. We compare results of this model with simulation and show good match. We also develop models to calculate source-destination throughput for the reservation MAC as used in the Joint Tactical Radio System to support both unicast and multicast traffic. These models are based on extending reduced load loss network models for wireless multicast traffic with the sharing of the wireless medium between a node and its (upto 2 hop) neighbors modeled by considering cliques of interfering nodes around a particular node. We compare results of this model with simulation and show good match with simulation. Once we have developed models to estimate throughput and blocking probabilities, we use these models to optimize total network throughput. In order to optimize total throughput, we compute throughput sensitivities of the reduced load loss network model using an implied cost formulation and use these sensitivities to choose the routing probabilities among multiple paths so that total network throughput is maximized. In any network scenario, MANETs can get disconnected into clusters. As part of the MANET design problem, we look at the problem of establishing network connectivity and satisfying required traffic capacity between disconnected clusters by placing a minimum number of advantaged high flying Aerial Platforms (APs) as relay nodes at appropriate places. We also extend the connectivity solution in order to make the network single AP survivable. The problem of providing both connectivity and required capacity between disconnected ground clusters (which contain nodes that can communicate directly with each other) is formulated as a summation-form clustering problem of the ground clusters with the APs along with inter-AP distance constraints that make the AP network connected and with complexity costs that take care of ground cluster to AP capacity constraints. The resultant clustering problem is solved using Deterministic Annealing to find (near) globally optimal solutions for the minimum number and locations of the APs to establish connectivity and provide required traffic capacity between disconnected clusters. The basic connectivity constraints are extended to include conditions that make the resultant network survivable to a single AP failure. In order to make the network single AP survivable, we extend the basic connectivity solution by adding another summation form constraint so that the AP network forms a biconnected network and also by making sure that each ground cluster is connected to atleast two APs. We establish the validity of our algorithms by comparing them with optimal exhaustive search algorithms and show that our algorithms are near-optimal for the problem of establishing connectivity between disconnected clusters