We present an analytical tool to enhance the blocking performance in the circuit-switched wide-area optical wavelength division multiplexed (WDM) networks with no wavelength conversion at the nodes. Given any network of arbitrary topology, the aim is to see if one can achieve the wavelength conversion (optimal) performance by using wavelength reassignment techniques in no conversion networks. If there is significant performance deviation, the tool identifies the critical points in the network which prevents the reassignment to totally remove wavelength continuity constraint (wcc) blocking. Once the critical points are identified, the tool appropriately modifies the routing such that the wavelength reassignment can achieve the optimal performance. © 2007 IEEE.

Ashok Jhunjhunwala

Department of Electrical Engineering

Blocking probability

Fiber optic networks

Optimal systems

Problem solving

Wavelength division multiplexing

ARBITRARY TOPOLOGY

Optimal performance

WAVELENGTH CONTINUITY CONSTRAINT (WCC) BLOCKING

WAVELENGTH REASSIGNMENT

OPTICAL FREQUENCY CONVERSION

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Analytical Tool to Achieve Wavelength Conversion Performance in No Wavelength Conversion Optical WDM Networks

IEEE International Conference on Communications

Reassignment of calls to different wavelengths on blocking can be used in WDM networks without wavelength conversion to get almost the same performance as that of WDM networks with wavelength conversion for circuit switched traffic [11]. However, in a few networks, we did find that while the reassignment on blocking does improve the performance of WDM networks without wavelength conversion, the performance falls short of that of wavelength conversion networks. In this paper, we analyze the reasons for this behavior in these networks. On identifying certain critical nodes as a cause of this behavior, we propose a rerouting technique around the critical node. With a small amount of rerouting, this bottleneck can be removed and the performance of WDM networks without wavelength conversion becomes almost equal to that of networks with wavelength conversion, thus making the wavelength conversion (costly) feature, as redundant. In this paper, we also propose a technique to carry out seamless wavelength reassignment so as not to disrupt traffic during the wavelength reassignment process. © 2008 IEEE.

Journal of Lightwave Technology

Re-routing at critical nodes to enhance performance of wavelength reassignment in all-optical WDM networks without wavelength conversion

In this paper, we consider the problem of enhancing the blocking performance, in the circuit-switched wide-area optical wavelength-division multiplexed (WDM) networks with no wavelength conversion at the nodes. The limitation of such a no conversion network is the wavelength continuity constraint (wcc) which requires the same wavelength on all the hops of the path. Whenever there is a session request, a lightpath has to be established in the network. If the lightpath could not be established, lightpath request rejection or call blocking occurs. As each lightpath is a substantial revenue and is long-lived, lightpath request rejection is highly unfavorable in the optical backbone networks. An optimal optical network is the one with wavelength conversion capability at the nodes. In these conversion networks, blocking occurs due to capacity exhaustion on the links and not due to wcc. Hence these networks have the lowest possible blocking probability (Pb) achievable for any given network. Our aim is to see if one can achieve this near optimal blocking performance in no conversion networks by using our proposed wavelength reassignment algorithms. In the reassignment technique, when the new call gets blocked due to wcc, the already established calls or lightpaths are wavelength reassigned, so as to create a wavelength-continuous route in order to accommodate the new call. During wavelength reassignment, the routes for all the calls remain the same, i.e. no rerouting is done. We have proposed two heuristic reassignment algorithms namely, MOLC and Random and have studied their performance on some standard backbone optical networks. Simulation results show that in these example networks, our proposed reassignment algorithm can mostly remove the blocking due to the wcc and can achieve the wavelength conversion performance. © 2007 Elsevier B.V. All rights reserved.

Optical Switching and Networking

Wavelength reassignment algorithms for all-optical WDM backbone networks

WDM Mesh Networks

Routing and Wavelength Assignment for Survivable Wavelength-Routed Networks

Optical Networks

Introduction to Optical Networks

Wavelength conversion has been proposed for use in wavelength-division multiplexed networks to improve efficiency. This study highlights systems challenges and performance issues which need to be addressed in order to incorporate wavelength conversion effectively. A review/survey of the enabling technologies, design methods, and analytical models used in wavelength-convertible networks is provided.

Fulltext

IEEE Journal on Selected Areas in Communications

Wavelength conversion in WDM networking

IEEE/ACM Transactions on Networking

Routing and wavelength assignment in all-optical networks

IEEE Communications Magazine

Multiwavelength lightwave networks for computer communication

Analytical tool to achieve wavelength conversion performance in no wavelength conversion optical WDM networks

Journal	IEEE International Conference on Communications
ISSN	05361486
Open Access	No