2297 9 archive 2 disk0/00/00/22/97 2008-07-03 16:09:39 2008-07-03 16:09:39 2008-07-03 16:09:39 article show Sumathi, M. nnsuma@yahoo.com Vanathi, P.T. ptvani@yahoo.com Sona College of Technology, Salem, India PSG College of Technology, Coimbatore, India pub Q none Congestion, Lightpath, WDM, Dynamic Traffic, Mesh Network, Virtual Topology Reconfiguration of a Wavelength Division Multiplexed (WDM) optical network is considered for varying traffic demands in the network. Reconfiguration is carried out with the aim of optimizing the objective function and minimizing the number of lightpath changes. This ensures the effective utilization of the network resources with minimum disruption to the network. In this paper, we present a new approach in which lightpaths with less traffic are considered for deletion during setup of a new lightpath. This increases the probability of setting up a new lightpath and decreases the value of the objective function; namely the congestion. Extensive simulation has been carried out for different traffic patterns. The congestion of the network and the number of lightpath changes has been studied. It is shown that deletion of lightpaths to free resources while setting up a new lightpath largely improves the congestion of the network. For slow varying traffic patterns, addition of one or two lightpaths minimized the congestion considerably. On the other hand, for rapid varying traffic patterns, minimizing load on one link might not considerably reduce congestion in the network. Therefore, multiple lightpath additions can enable decongesting multiple lightpaths in a single reconfiguration stage and balance the load in the network. 2008 published Malaysian Journal of Computer Science 21 1 Faculty of Computer Science and Information Technology 57-65 TRUE 0127-9084 http://ejum.fsktm.um.edu.my/ArticleInformation.aspx?ArticleID=629 [1] C.SivaRamMurthy and M.Gurusamy, WDM Optical Networks: Concepts, design and algorithms, PHI, 2002. [2] R.Dutta and G.N.Rouskas, “A survey of VT design algorithms for wavelength routed optical networks”, TR-99- 06, May 12, 1999. [3] Raja Dutta and Indranil Sengupta, “Static and Dynamic Connection Establishment in WDM Optical Networks: A Review”, IETE Journal of Research, May/June 2005, pp.209 – 221. [4] Amrinder S.Arora, Suresh Subramaniam, Hyeong-Ah Choi, “Logical Topology Design for Linear and Ring Optical Networks”, IEEE Journal on Selected Areas in Communications, vol. 20(1), January 2002, pp.62-74. [5] B.Mukherjee, D.Banerjee, S.Ramamurthy, A.Mukherjee, “Some principles for designing a wide area WDM optical network”, IEEE/ACM Transactions on Networking, vol. 4(5), October 1996, pp.684-696. [6] Rajesh M. Krishnaswamy, Kumar N. Sivarajan, “Design of Logical Topologies: A Linear Formulation for Wavelength-Routed Optical Networks with No Wavelength Changers”, IEEE/ACM Transactions on Networking, vol. 9(2), April 2001, pp.186-198. [7] R.Ramaswami, K.N.Sivarajan, “Design of logical topologies for wavelength routed optical networks”, IEEE Selected Areas in Communication, vol. 4(5), June 1996, pp.840-851. [8] M.Sumathi and P.T.Vanathi, “Minimizing Congestion in Optical WDM Networks for Dynamic Traffic”, in Proc. of IEEE INDICON 2005, IIT, Chennai, India, Dec. 2005, pp. 101-104. [9] Stefano Bregni, Ugo Janigro, Achille Pattavina, “Optimal allocation of limited optical layer resources in WDM networks under static traffic demand”, Photonic Network Communications, vol. 5(1), January 2003, pp.248-252. [10] Y.Xin, G.N.Rouskas, H.G.Perros, “On the physical and logical topology design of large scale optical networks”, Journal of lightwave technology, vol. 21(4), April 2003, pp.904-915. [11] D.Banerjee, B,Mukherjee, “Wavelength-routed optical networks: Linear formulation, Resource Budgeting tradeoffs and a reconfiguration study”, IEEE/ACM Transactions on Networking, vol. 8(5), October 2000, pp.598-607. [12] N.Sreenath, B.H.Gurucharan, G.Mohan, C.Siva Ram Murthy, “A two-stage approach for virtual topology reconfiguration of WDM optical networks”, Optical Networks Magazine, May/June 2001, pp.58-71. [13] A.Gencata, B.Mukherjee, “Virtual topology adaptation for WDM mesh networks under dynamic traffic”, IEEE/ACM Transactions on Networking, vol. 11(2), April 2003, pp.236-247. [14] Anuradha Narula_Tam, Eytan Modiano, “Dynamic load balancing in WDM packet networks with and without wavelength constraint”, IEEE Journal on Selected Areas in Communication, vol. 18(10), October 2000, pp.1972-1980. [15] R.Ramaswami and K.N.Sivarajan, Optical Networks: A practical perspective, Morgan Kaufmann Pub., 1998