Nondegenerate buffers: an approach for building large optical memories

Tancevski, L.; Tamil, Lakshman S.; Callegati, Franco

doi:10.1109/68.775350

Cited by 67 publications

(35 citation statements)

References 5 publications

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“…The method consists in converting contending packets/bursts from an unavailable wavelength to an available one, with either no restriction (full conversion, so that all available wavelengths can be reached [3,22]) or a restriction on either wavelength conversion range [14,15] or number of available converters [8]. Secondly, optical buffering consists in delaying packets/bursts that find a resource unavailable by sending it through a piece of fiber of sufficient length, so that the resource is available again when the packet/burst leaves the delay line [1,2,9,10,20,21,24]. Thirdly, in a multi-fiber setting, deflection or alternate routing consists in routing packets/bursts that find a resource unavailable to another node through an different, available output fiber [5,12]; this is done preferably topology-and congestion-aware [30].…”

Section: 1mentioning

confidence: 99%

“…Opposed to horizon scheduling, a contribution revealing the actual complexity of the channel and delay selection algorithm is [24], showing that the optimal CDS algorithm should maintain the position of all voids created on all channels and all delay lines, in order to exploit the (buffering) capacity that is available within the voids. The resulting CDS algorithm is called the void-filling scheduling algorithm, and is rigorously studied in [26], and this for various traffic conditions, buffer sizes and algorithm parameter settings.…”

Section: 1mentioning

confidence: 99%

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On the optimality of packet-oriented scheduling in photonic switches with delay lines

Rogiest¹,

Turck²,

Laevens³

et al. 2011

Numerical Algebra, Control &Amp; Optimization

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Abstract. Addressing the bandwidth inefficiency problem of current IP over DWDM backbone switching, Optical Packet/Burst Switching (OPS/OBS) provide viable solutions, capitalizing on statistical multiplexing gain, through packet-oriented scheduling. To resolve packet/burst contention, the involved photonic switches contain wavelength converters and fiber delay lines, controlled through a channel and delay selection (CDS) algorithm. Recently proposed CDS algorithms all rely on heuristics, of which the optimality is unexamined to date.This paper presents an in-depth analysis of the optimality of CDS algorithms. Methodologically, we rely on Markov chain analysis for performance evaluation, combined with a discrete Markov Decision Process formulation of the optimization problem, optimized for fast calculation, allowing to determine the exact optimum of a specific given setting of the switch, through numerical algebra solution techniques. Results point out that, for the basic switch setting assumed, of all known CDS algorithms, an algorithm called MING (MINimal Gap) is close to optimal, but never strictly optimal. Various graphs support this, showing that an algorithm optimal for any traffic load cannot (in general) be devised. Results for several other switch settings further confirm this, showing how known CDS algorithms might be modified, to attain improved control robustness.

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Section: 1mentioning

confidence: 99%

Section: 1mentioning

confidence: 99%

On the optimality of packet-oriented scheduling in photonic switches with delay lines

Rogiest¹,

Turck²,

Laevens³

et al. 2011

Numerical Algebra, Control &Amp; Optimization

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show abstract

“…The lengths of the FDLs are consecutive multiples of a basic value D called the granularity. This is called a degenerate delay buffer [8], in which incoming packets sent through the j-th (j = 0 . .…”

Section: A Assumptionsmentioning

confidence: 99%

Fill the Void: Improved Scheduling for Optical Switching

Hautegem

Rogiest

Bruneel

2015

2015 27th International Teletraffic Congress

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Abstract-With ever-increasing demand for bandwidth, optical packet/burst switching is proposed to utilize more of the available capacity of optical networks in the future. In these packet-based switching techniques, packet contention on a single wavelength is resolved effectively by means of Fiber Delay Lines. The involved scheduling algorithms are typically designed to minimize packet loss and/or packet delay. By filling so-called voids, void-filling algorithms are known to outperform their non-void-filling counterparts. This however comes at a large computational cost as the void-filling algorithms have to keep track of beginnings and endings of all voids. This is opposed to the non-void-filling algorithms which only have to keep track of a single system state variable. We therefore propose a new type of algorithm that selectively creates voids that are larger than strictly needed, only when these will likely be filled. Results obtained by Monte Carlo simulation show that selective void creation can jointly reduce packet loss by 50% and packet delay by 18%, without imposing a high computational cost.

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“…To show the effect of the selection of the fibre distribution, the travelling buffer has been simulated with both a degenerate (increasing uniformly) and non-degenerate distribution (increasing non-uniformly, often implemented with an exponential increase in fibre lengths) [42]. Fixed FDL lengths were not considered as it was shown in Ref.…”

Section: Travelling Buffersmentioning

confidence: 99%

Architectures and Buffering for All-Optical Packet-Switched Cross-Connects

et al. 2006

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This paper considers the performance of an alloptical packet-switched cross-connect. All-optical header processing and all-optical routing are implemented in the cross-connect architectures. The main metric considered to measure the performance is the packet loss ratio for the buffering. This is influenced primarily by three factors. The first is the cross-connect architecture: feedback or feed-forward buffering, incorporating wavelength domain contention resolution. The second is the selection of the fibre delay line distribution: degenerate or non-degenerate distributions. And the third is the traffic load together with the traffic model used for the performance analysis: a Poisson distribution or a selfsimilar model. It is shown that the optimal implementation of a feedback buffer requires a technique such as overflow buffering as well as the superior performance of an all-optical switch in order to maintain signal quality through multiple recirculations.

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Nondegenerate buffers: an approach for building large optical memories

Cited by 67 publications

References 5 publications

On the optimality of packet-oriented scheduling in photonic switches with delay lines

On the optimality of packet-oriented scheduling in photonic switches with delay lines

Fill the Void: Improved Scheduling for Optical Switching

Architectures and Buffering for All-Optical Packet-Switched Cross-Connects

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