62 research outputs found

    A Priority Based Optical Header Contention Resolution in Optical Burst Switching Networks

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    OBS is a promising switching paradigm for the next-generation Internet.In OBS, data packets are assembled into variable size data burst which are transmitted optically over Dense Wavelength Division Multiplexing(DWDM)networks without O/E/O conversion. The control packet is sent before the data burst to reserve resources and configure switches along the path .The control packet is sent along the separate control channel and goes through O/E/O conversion. We have discussed various OBS signalling protocols and Burst Scheduling Algorithms. As the data channel bandwidth will grow it will lead to the overloading of the control path. In this thesis we have proposed an algorithm to resolve the contention of the optical header. The algorithm assigns the priority to each control packet arriving at the same time .The control packet with highest priority is selected for processing. Simulation results have shown that the technique is effective in improving the throughput

    Equivalent random analysis of a buffered optical switch with general interarrival times

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    We propose an approximate analytic model of an optical switch with fibre delay lines and wavelength converters by employing Equivalent Random Theory. General arrival traffic is modelled by means of Gamma-distributed interarrival times. The analysis is formulated in terms of virtual traffic flows within the optical switch from which we derive expressions for burst blocking probability, fibre delay line occupancy and mean delay. Emphasis is on approximations that give good numerical efficiency so that the method can be useful for formulating dimensioning problems for large-scale networks. Numerical solution values from the proposed analysis method compare well with results from a discrete-event simulation of an optical burst switch

    Segmentation-based nonpreemptive channel scheduling algorithms for optical burst-switched networks

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    MANAGING CONTENTION AVOIDANCE AND MAXIMIZING THROUGHPUT IN OBS NETWORK

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    Optical Burst Switching (OBS) is a promising technology for future optical networks. Due to its less complicated implementation using current optical and electrical components, OBS is seen as the first step towards the future Optical Packet Switching (OPS). In OBS, a key problem is to schedule bursts on wavelength channels whose bandwidth may become fragmented with the so-called void (or idle) intervals with both fast and bandwidth efficient algorithms so as to reduce burst loss. In this paper, a new scheme has been proposed to improve the throughput and to avoid the contention in the OBS network. The proposed scheme offers the same node complexity as that in general OBS networks with optical buffers. Also, it avoids burst blockings in transit nodes, turning it into an efficient and simple burst contention avoidance mechanism. Simulation results show that the proposed scheme has improvement of 15% in terms of burst loss probability as compared to OBS existing schemes and also maximizes the throughput of the network without deteriorating excessively other parameters such as end to end delay or ingress queues

    An assembly and offset assignment scheme for self-similar traffic in optical burst switching

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    Includes bibliographical references.Optical Burst Switching (OBS) is a viable technology for the next generation core network. We propose an FEC-assembly scheme that efficiently assembles self-similar traffic and a Pareto-offset assignment rather than a constant offset assignment. Two buffers, a packet buffer and a burst buffer, are implemented at the Label Edge Router (LER), buffering traffic in the electronic domain. The assembler, between the packet and burst buffers, is served by the packet queue while the assembler serves the burst queue. We outline advantages of why burst assembly cannot be implemented independent of offset assignment. The two schemes must be implemented in a complementary way if QoS is to be realized in an OBS network. We show that there is a direct relation between OBS network performance with burst assembly and offset assignment. We present simulation results of the assembly and offset assignment proposals using the ns2 network simulator. Our results show that the combination of the proposed FEC-Based assembly scheme with the proposed Pareto-offset assignment scheme give better network performance in terms of burst drop, resource contention and delay. Key to any traffic shaping is the nature traffic being shaped. This work also compares performance of both traditional exponential traffic with realistic Self-Similar traffic of Internet traffic on the proposed assembly and offset assignment schemes. In our simulations, we assume that all Label Switch Routers (LSR) have wavelength converters and are without optical buffers. We use Latest Available Unused Channel with Void Filling (LAUC-VF) scheduling scheme and use Just Enough Time (JET) reservation scheme

    An emission and discard priority scheme for optical burst switched networks

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    Word processed copy.Includes bibliographical references (leaves 76-79).Optical burst switching (OBS) is a promising technology designed to meet the growing demands for internet handwidth and better Quality of Service (QoS). This technology provides all optical and high speed switching to overcome the bottleneck of electronic routers in the core network. In this thesis, I describe several critical issues that affect OBS networks. I highlight the need to resolve contention efficiently and cost-effectively to improve QoS in OBS networks

    Trends in optical burst switching

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    Node design in optical packet switched networks

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