Fractional Lambda Switching Principles of Operation and Performance Issues

Abstract

This paper introduces fractional lambda (λ) switching (FλS) and studies its blocking issues. FλS is a completely novel and extremely promising technology for the realization of low complexity, high scalability switches. FλS is unique in enabling the implementation of alloptical dynamical switching with current state-of-the-art components. Being a new technology, FλS requires investigation, especially for what its performance and efficiency are concerned, in order for its deployment to be undertaken by network operators. In this view, the present work is extremely relevant since it is instrumental in enabling a widespread deployment of such a promising technology.Resource reservation over an FλS network requires a schedule. As in other scheduling cases, a call may not be accepted, even though there is enough capacity, because the schedule is not available-the call is then considered blocked. This work studies the probability of call blocking as a function of link utilization.The results show that (especially if multiple wavelength division multiplexing channels are deployed on optical links between fractional λ switches) high link utilization can be achieved with negligible call blocking, even when realizing switching fabrics as Banyan networks.This work is unique since it is related to a unique technology. Even though FλS has similarities with circuit switching (i.e., SONET/SDH switching), its basic working principle, pipeline forwarding, is fundamentally different since it is based on the deployment of UTC (Universal Coordinated Time) to control the forwarding of data units in the network. Pipeline forwarding provides FλS with unique features, which makes existing methodologies to study the performance of both packet switching and circuit switching not applicable to FλS. This determines the novelty and significance of this work and explains the lack of related work.The results produced by this work can be used to encourage the deployment of FλS. Moreover, the work presents a basic approach that can be used in future FλS performance studies.A small subset of the simulation results have been presented at the IEEE International Conference on Communications (ICC2002), Optical Networking Symposium, New York, NY, USA, Apr. 2002. However, no information on the simulation methodology and tool have been thus far published or are under revision for possible publication. Abstract -This paper introduces fractional lambda (λ) switching (FλS) and studies its blocking issues. FλS uses a global common time reference (CTR) for implementing pipeline forwarding (PF) inside the network. A global CTR is conveniently realized with the UTC (coordinated universal time) standard. Resource reservation over an FλS network requires a schedule. As in other scheduling cases, a call may not be accepted, even though there is enough capacity, because the schedule is not available-the call is then considered blocked. This work studies the probability of call blocking as a function of link utilization. The results show that (especially if multip...

Efficient IP Traffic over Optical Network Based on Wavelength Translation Switching

“…Considering an optical network so that an internetwork has been established by connecting various layer-3 devices with optical fiber channel based on lambda switching [3][4][5][6][7][8][9]12,16]. There are many optical communication and FPGA based work is also going in [17][18][19][20].…”

An Efficient Scheduling Algorithm for Time-Driven Switching Networks

“…The TDS network operation principles were described in depth in [2]. The following is a brief summary that is needed for understanding of our scheduling search design and analysis.…”

“…The schedule search algorithm presented in [2] is suitable only for the simple IF case of single channel per link, not dealing with the complexity introduced by WDM and NIF, which is the focus of this paper. The work [7] addresses the RWTA (Route, Wavelength, Time slot Assignment) problem in time-shared wavelength-routed WDM networks.…”

Contention avoidance in bufferless slotted optical packet switched networks with egress switch coordination

“…Our objective is to reduce overall PLR in core switches by using optical slot reservation in buffer-less slotted-OPS network while controlling buffer size and buffering delay in ingress switches. Fractional lambda switching (FλS) [23,24] is a dynamic all-optical switching technique where fractions of wavelengths called time frames are dynamically switched in core switches based on reservation tables in them. In FλS, a common-time-reference such as global positioning system (GPS) is used in all core switches to synchronize their time frames.…”

“…This lets the FλS to reserve resources for each flow at the network. However, FλS has been designed for circuit based traffic and it needs common-timereference in all core/edge switches [23,24]. We want to reserve optical slots in buffer-less OPS network without using common-time-reference.…”