C.S.R. Murthy

Bio: C.S.R. Murthy is an academic researcher. The author has contributed to research in topic(s): Heuristics & Reliability (computer networking). The author has an hindex of 1, co-authored 1 publication(s) receiving 6 citation(s).

Distributed network control for establishing reliability-constrained least-cost lightpaths in WDM mesh networks

Abstract: A control scheme which is used to set up and tear down lightpaths, should not only be fast and efficient, must also be scalable, and should try to minimize the number of blocked connections; while satisfying the requested level of fault-tolerance. In this work we propose a distributed control scheme based on preferred link approach for establishing reliability-constrained least-cost lightpaths, by choosing the reliability of a lightpath to denote the level of fault-tolerance required by the connection request. Four heuristics are proposed and their performance is studied through extensive simulation experiments. The simulation results suggest that our heuristics provide better performance compared to other distributed protocols available, in terms of average call acceptance rate, average path cost, average routing distance, and average connection setup time; when the connection requests with different levels of fault-tolerance requirements arrive to and depart from the network randomly.

Distributed dynamic QoS-aware routing in WDM optical networks

Abstract: As the WDM technology matures and the demand for bandwidth increases, dynamic provisioning of lightpaths at the WDM layer becomes an important and challenging problem. Any distributed algorithm for routing dynamic traffic should be simple, efficient, and also scalable. Most of the multimedia and real-time applications require specific quality of service (QoS), hence it is important that the routing algorithm should provide lightpaths which satisfy the required QoS. The QoS also includes fault-tolerance besides guarantees on different metrics such as bandwidth, bit-error-rate, and reliability. In this paper, we propose distributed dynamic routing algorithms for QoS constrained routing and survivable routing, based on preferred link routing approach. For QoS constrained routing, we provide a common framework for routing connections with constraints on different types of metrics such as bandwidth (a concave metric), delay and bit-error-rate (additive metrics, and should be minimum for a best QoS path), and reliability (multiplicative metric, and should be maximum for a best path). The framework considers multiple QoS constrained routing which is an NP-Complete problem. We also propose a distributed routing algorithm for fault-tolerant connections, and describe how dedicated and shared protection can be provided in the case of single link failures. We have conducted simulation experiments with bit-error-rate and reliability as the metrics to evaluate the performance of the proposed multiple constrained QoS routing algorithm. We have also studied the performance of the fault-tolerant routing in terms of call acceptance ratio, cost of the path, hop length, and call setup time, and compared the results with that of an existing approach. Our experimental results suggest that our algorithms out perform the existing methods with respect to the average number of calls accepted.

QoS Based OVPN Connection Set up and Performance Analysis

Abstract: Due to high demand of optical virtual private network (OVPN) connection setup with guaranteed quality of service (QoS) requirement, it is necessary to provide such application by the provider network. In order to support this we propose a QoS based OVPN connection set up mechanism over WDM network to the end customer, which also maintains the minimum blocking probability. The proposed WDM network model can be specified in terms of QoS parameters such as bandwidth and delay. We estimated those QoS parameters based on available resources and QoS requirements in terms of quality factor (Q-Factor). In this mechanism the OVPN connections also can be created or deleted according to the availability of the resources. In this paper we have considered the effect of polarization mode dispersion for the computation of Q-Factors which is prominent effect at high speed networks. The goal of the work is to dynamically provide a best OVPN connection during frequent arrival of connection requests with QoS requirements. .

Distributed Real Time Algorithms and Design Concepts for Next Generation Survivable Optical Networks

Abstract: Motivated by the rapid growth of the internet, the increasing demand and the nature of traffic, wavelength division multiplexing (WDM) is now beginning to expand from a network core technology towards the metropolitan and access networks. However, huge amount of data can be lost and large numbers of users can be disrupted during the times of failure in WDM optical networks. Therefore, a reliable optical layer that can quickly and efficiently respond to failures, such as fiber cuts, is a critical issue to users and service providers. The major challenge in survivable mesh networks is the design of distributed management protocols and resource allocation algorithms that allocate network resources efficiently and are able to quickly recover from a failure. This issue is particularly more challenging in optical networks operating under distributed control, where there is no global information available; and under wavelength continuity constraint, where the same wavelength must be assigned on all links in the selected path. This thesis presents a number of new distributed protocols and algorithms to solve these challenges. The second part of this thesis provides new distributed frameworks to support Quality of Service (QoS) differentiation. These frameworks provide differentiated protection services to meet customers' availability requirements effectively. We describe the availability-analysis for connections with different protection schemes. Through this analysis, we show how connection availability is affected by resource sharing. Based on the availability analysis, the proposed framework provisions each connection in which an appropriate level of protection is provided according to its predefined availability requirement. We consider the networks without wavelength conversion capability as well as dynamic traffic environment. In these distributed frameworks we propose several distributed schemes to provision and manage connections cost-effectively while satisfying the existing and new connections availability requirements. To the memory of my father Mahmoud Alsukhni (Abu Ziad) and to my mother Maryam Nawasreh (Um Ziad)

A framework for distributed provisioning availability-guaranteed least-cost lightpaths in WDM mesh networks

Abstract: The trend in the development of intelligent optical networks is the move towards a unified solution, to support voice, data, and various services. Nowadays, different applications may need different levels of protection and differ in how much they are willing to pay for the service they get. A control scheme which is used to set up and tear down lightpaths, should not only be fast and efficient, but also be scalable. In addition, it should also try to minimize the connection cost and the number of blocked connections while satisfying the requested level of availability. In this work we choose the availability of a connection as a quality of service (QoS) parameter to denote different levels of protection. It is proven that the Availability-Guaranteed least-cost (AGLC) routing problem is NP-complete. We propose a distributed control scheme based on parallel fixed alternative routing approach for establishing AGLC lightpaths. The proposed framework performance is studied through extensive simulation experiments on wavelength selective network with different traffic loads. The simulation results show that our proposed framework provides better performance in terms of average blocking probability, and average routing distance average path cost.

Quality of service estimation techniques for an optical virtual private network over wdm/dwdm network

Abstract: Quality of Service (QoS) in optical virtual private network (OVPN) is a demanding factor for communication network application. To provide desired QoS, the control plane in an all optical network (AON) has to be designed to maximize the quality of an OVPN connections (OVPNC). The AON is generally characterized by various network and physical layer parameters, which are used by the OVPN control manager (OVPNCM) for the estimation of quality factor (Q-Factor) for a set of possible OVPNC. It is observed that, not only the network layer parameters, but also the physical layer parameters called as physical layer impairments (PLIs) have impact on connection quality. In optical networks, the PLIs are incurred by non-ideal optical transmission media and accumulate along the optical connection. The overall effect of PLIs can be analyzed to determine the feasibility of quality based OVPNC. It is important to understand the process and provide the network as well as the PLI information to the OVPNCM and use this information efficiently to compute feasible connections along with Q-Factor values. Based on these, four different QoS estimation techniques have been proposed here.