Browsing by Author "Vardhan, Hars"
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Item Building alternate multitasking trees in MPLS networks(The University of Texas at Dallas, 2013-05-23) Tang, Limin, 1977-; Billenhalli, Shreejith; Vardhan, Hars; Tacca, Marco, 1973-; Fumagalli, Andrea; Monti, Paolo, 1973-; Eric Jonsson School of Engineering and Computer Science. Open Networking Advanced Research (OpNeAR) Laboratory.; Next Generation Optical Network (NeGONet) Group; Kungl. Tekniska högskolan (KTH). Photonics and Microwave Engineering (FMI). School of Information and Communication Technology; Royal Institute of Technology (Kista, Sweden)An algorithm for computing alternate multicast trees in packet transport networks is proposed in this paper. The algorithm efficiently computes multiple sub-optimal tree candidates for a given multicast service request. The algorithm builds on the widely used computation of K ordered loopless shortest paths and can be applied to any connected network topology. Simulation experiments obtained for a multiprotocol label switching (MPLS) network are presented to evaluate the effectiveness and performance of the algorithm.Item Finding a simple path with multiple must-include nodes(The University of Texas at Dallas, 2013-05-23) Vardhan, Hars; Billenahalli, Shreejith, 1982-; Huang, Wanjun, 1978-; Razo, Miguel; Sivasankaran, Arularasi; Tang, Limin, 1977-; Monti, Paolo, 1973-; Tacca, Marco, 1973-; Fumagalli, Andrea; Eric Jonsson School of Engineering and Computer Science. Open Networking Advanced Research (OpNeAR) Laboratory.This document presents an algorithm to find a simple path in the given network with multiple must-include nodes. The problem of finding a simple path with only one must-include node can be solved in polynomial time using lower bound max-flow approach. However, including multiple nodes in the path has been shown to be a NP-Complete. This problem may arise in network areas such as forcing the route to go through particular nodes, which have wavelength converter (optical), have monitoring provision (telecom), have gateway functions (in OSPF) or are base stations (in MANET). Also, network standards allow loose definition of routing by requiring one or more nodes to be in the routing of Link State Packet. In this document, a heuristic algorithm is described to find a simple path between a pair of terminals, which has constraint to pass through a certain set of other nodes. The algorithm is comprised into two main steps: (1) considering a pair of nodes in sequence from source to destination as a segment and then computing candidate paths between each segment, and (2) combining paths, one from each segment, in order to make simple path from source to destination. The max-flow approach is used to find candidate paths, a which provides maximum number of edge disjoint paths for individual segments. The second step of the algorithm uses backtracking algorithm for combining paths. The time complexity of the first step of the algorithm is O(kiVIIEI 2 ), where k is the number of must-include nodes. The time complexity of step (2) depends upon total number of candidate paths which are not touching any one of the candidates of other segments. So, the worse case time complexity of step (2) is O(.Ak), where .A is the maximum nodal degree of the network. However, we show that step (2) has minimal effect on the algorithm and it does not grow exponentially with k in this application. Later, we also show that initial re-ordering of the given sequence of must-include nodes can improve the result. The experimental results show that the algorithm is successful in computing near optimal path in reasonable time. keywords: constrained path computation, graph theory, heuristic algorithm, max flow, network route.Item The PlaNet-PTN module: a single layer design tool for packet transport networks(The University of Texas at Dallas, 2013-05-23) Razo, Miguel; Litovsky, Arie; Huang, Wanjun, 1978-; Sivasankaran, Arularasi; Tang, Limin, 1977-; Vardhan, Hars; Tacca, Marco, 1973-; Fumagalli, Andrea; Monti, Paolo, 1973-; Eric Jonsson School of Engineering and Computer Science. Open Networking Advanced Research (OpNeAR) Laboratory.PlaNet is a multilayer network planning tool developed at the University of Texas at Dallas. This paper illustrates some of the features of PlaNet-PTN, one of the modules available in the PlaNet tool. PlaNet-PTN can be used to design and plan a single layer packet transport network (PTN). Quality of protection, routing constraints, minimization of the network equipment cost, and user's desired run time of the tool are just some examples of the features available in PlaNet. As shown in the paper, the PlaNet-PTN planning module is able to provide, among others, optimization of Label Switched Path (LSP) routes, link capacity placement, node and link equipment configuration.Item A scalable wavelength assignment algorithm using minimal number of wavelength converters in resilient WDM networks(The University of Texas at Dallas, 2013-06-18) Razo, Miguel; Billenahalli, Shreejith; Huang, Wanjun, 1978-; Sivasankaran, Arularasi; Tang, Limin, 1977-; Vardhan, Hars; Tacca, Marco, 1973-; Fumagalli, Andrea; Monti, Paolo, 1973-; Eric Jonsson School of Engineering and Computer Science. Open Networking Advanced Research (OpNeAR) Laboratory.; Royal Institute of Technology. NeGONet Group.Careful wavelength assignment (WA) to support lambda services is necessary to reduce the total number of wavelength converters (WCs), which are required every time the wavelength continuity constraint cannot be met in wavelength division multiplexing (WDM) networks. With the successful introduction of reconfigurable optical add-drop multiplexers (ROADMs) and related technologies, WDM networks are now growing in size, both in the number of optical nodes and number of wavelengths supported, thus requiring WA algorithms that scale with the network size. This paper presents a scalable and efficient WA algorithm that aims to reduce the total number of WCs in WDM networks bearing static lambda services. The WA algorithm is applicable to both unprotected and (dedicated) protected lambda services. In the latter case, wavelength continuity constraint between the working and the protection path is taken into account. The WA algorithm is then used to quantify the tradeoff between using tunable optical transceivers versus number of WCs to cope with the wavelength continuity constraint.Item Shared protection ILP formulation(The University of Texas at Dallas, 2013-06-18) Huang, Wanjun, 1978-; Razo, Miguel; Billenahalli, Shreejith; Sivasankaran, Arularasi; Tang, Limin, 1977-; Vardhan, Hars; Monti, Paolo, 1973-; Tacca, Marco, 1973-; Fumagalli, Andrea; Eric Jonsson School of Engineering and Computer Science. Open Networking Advanced Research (OpNeAR) Laboratory.; Royal Institute of Technology. NeGONet Group.