Scaling photonic packet switches to a large number of ports

Dorren, Hjs Harm; Lucente, S. Di; Raz, O.; Calabretta, Nicola; Nazarathy, Yoni

doi:10.1109/ico-ip.2011.5953706

Cited by 5 publications

(11 citation statements)

References 12 publications

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“…While broadband photonic switches benefit from the extensive range of architectures developed for electronic switches, wavelength-selective routing requires carrier wavelengths to be changed at each stage for the fullest connectivity. Dorren et al have developed a modular architecture with distributed control and wavelength conversion to enable scaling to hundreds of connections [56,57]. Packet routing and flow-control experiments have been performed using a monolithic 4×4×4λ space and wavelength selective switche as the switching module [58,59].…”

Section: Space and Wavelengh Selective Cross-connectmentioning

confidence: 99%

Advances in integrated photonic circuits for packet-switched interconnection

Williams

2014

SPIE Proceedings

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Sustained increases in capacity and connectivity are needed to overcome congestion in a range of broadband communication network nodes. Packet routing and switching in the electronic domain are leading to unsustainable energy-and bandwidth-densities, motivating research into hybrid solutions: optical switching engines are introduced for massive-bandwidth data transport while the electronic domain is clocked at more modest GHz rates to manage routing. Commercially-deployed optical switching engines using MEMS technologies are unwieldy and too slow to reconfigure for future packet-based networking. Optoelectronic packet-compliant switch technologies have been demonstrated as laboratory prototypes, but they have so far mostly used discretely pigtailed components, which are impractical for control plane development and product assembly.Integrated photonics has long held the promise of reduced hardware complexity and may be the critical step towards packet-compliant optical switching engines. Recently a number of laboratories world-wide have prototyped optical switching circuits using monolithic integration technology with up to several hundreds of integrated optical components per chip. Our own work has focused on multi-input to multi-output switching matrices. Recently we have demonstrated 8×8×8λ space and wavelength selective switches using gated cyclic routers and 16×16 broadband switching chips using monolithic multi-stage networks. We now operate these advanced circuits with custom control planes implemented with FPGAs to explore real time packet routing in multi-wavelength, multi-port test-beds. We review our contributions in the context of state of the art photonic integrated circuit technology and packet optical switching hardware demonstrations. INTEGRATED PHOTONIC PACKET SWITCHESPhotonics switching technologies can be broadly classed in terms of wavelength operations. Photonic space switches route massive bandwidth signals independently of signal wavelength and number of multiplexed wavelength channels. Wavelength selective switches operate on multiplexed data streams to re-route fine granularity streams at the wavelength scale. The third class of photonic switch technologies enables the changing of carrier wavelengths at the photonic layer, offering considerable system level flexibility. Photonic and wavelength selective switches are already deployed in telecommunications networks, offering network flexibility advantage within tight cost and energy constraints [1][2][3][4]. Performing these functions at the photonic layer avoids the high energy costs and delays associated with opto-electronic conversions and electronic de/serialisations. The highest connectivity circuits have been based on low loss and high connectivity 3-D MEMS switching engines, but these are inherently free-space systems and require complex, precision assembly. Connectivity can already extend to many hundreds and thousands of connections, but there are concerns about the scaling properties in term of equipment cost, modularity and size....

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Section: Space and Wavelengh Selective Cross-connectmentioning

confidence: 99%

Advances in integrated photonic circuits for packet-switched interconnection

Williams

2014

SPIE Proceedings

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“…An appropriate scheduling algorithm along with edge electronic buffers enables a contention-free optical burst switching core network. The idea of building large-scale optical burst switches with edge electronic buffers has been the motivation of various research efforts [83][84][85][86].…”

Section: Optical Burst Switching With Edge Electronic Buffersmentioning

confidence: 99%

Optical Switching in Next Generation Data Centers

Testa¹,

Pavesi²

2018

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This thesis presents advanced optical connectivity solutions for next-generation data centers, spanning millions of processing cores. The wavelength routing of optical packets based on arrayed waveguide gratings (AWGs), tunable wavelength converters (TWCs), and fiber delay lines (FDLs) is a disruptive technology for capacity, footprint, and flexibility requirements of massive cloud data centers. We develop a wavelength-division multiplexed (WDM) design based on Birkhoff-von Neumann architecture as a bitrate transparent, scalable solution to switching bottlenecks in data center networks. As no mature all-optical buffering technology is currently available, central to our design is the buffering strategy that we adopt to store contending packets. Due to the limited number of FDLs, packet drops are common in optical packet switching (OPS) data centers and limit the network throughput. In a practical scenario, physical layer impairments, predominantly amplified spontaneous emission (ASE) noise and crosstalk, degrade Q-factor and lead to additional packet drops. To examine the performance of optical buffer units more accurately, we develop a unified analysis framework, integrating the network layer and the physical layer effects. Using this framework, we refine our architectures and provide guidelines for minimizing the physical layer impact. Besides, optical switch designs should not neglect the diversity of data center traffic patterns when developing connectivity solutions. Empirical studies of data center network traffic reveal that server traffic exhibits strong spatial and temporal correlations. We examine the effectiveness of an AWG-based load balancer with round-robin tuning TWCs in resolving congestion penalties in the data center network. Our cross-layer analysis suggests that the physical layer impairments due to the load balancer hardware could counteract its potential gains and lead to significant throughput degradation. To resolve this challenge, we develop a novel modular router architecture based on WDM shared recirculation buffers that integrates the functions of load balancing and routing and maximizes the optical buffering gains. The router employs a load-balancing scheduler to maximize throughput and minimize delay. Our mathematical analysis and Monte Carlo simulations show that the consolidation of optical buffer slots into WDM FDLs accompanied with internal load balancing leads to a virtually lossless router, resilient to data center traffic anomalies.ii

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“…Because there is no centralized control, computation times no longer depend on the architecture size. Thus, latency and control computation requirements do not limit scalability, and the number of ports can be increased beyond the thousands order [12,13]. In [14][15][16] we have experimentally demonstrated 40 Gbit∕s operation of a modular 16 × 16 WDM OPS with control time as low as 25 ns and total power consumption of 76 pJ∕bit by using either off-the-shelf optical components or photonic integrated devices.…”

Section: Introductionmentioning

confidence: 99%

“…In [17] we have experimentally demonstrated the performance of the WDM OPS with flow control and packet retransmission in the case of slotted uniform traffic. In [13] we present a discussion on the scalability in terms of optical components, optical losses, power consumption, and costs as the port count increases. The technological roadmap and feasibility to realize a largeport-count WDM OPS based on highly distributed control is also described in detail in [13].…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

On the Performance of a Large-Scale Optical Packet Switch Under Realistic Data Center Traffic

Calabretta¹,

Centelles²,

Lucente³

et al. 2013

J. Opt. Commun. Netw.

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High-speed, submicrosecond-latency, largeport-count (thousands) optical packet switches (OPSs) for intercluster communication networks can become a key element in the deployment of cloud-oriented largescale data centers. In this work we numerically investigate the performance of a large-port-count wavelength-division multiplexing (WDM) OPS based on a Spanke-type architecture with highly distributed control. We analyze it under a data center traffic model to determine its suitability for this type of environment. Results indicate that the proposed architecture can be scaled to 4096 ports while providing packet loss below 10 −6 and latency under 1 μs, with a total switching capacity over 55 Tbits∕s. Additionally, we propose and analyze two WDM OPS architectures. The first one detects and processes small and large-sized Ethernet packets with two parallel switches. The second architecture includes multiple receivers to decrease packet losses and latency while using very limited electronic buffers. Results indicate that both techniques can lead to substantial improvements. In terms of packet loss and latency, they allow up to 40% higher input load with respect to the original WDM OPS architecture.

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Scaling photonic packet switches to a large number of ports

Abstract: We investigate the impact of switching architectures that scale to thousands of ingress and egress nodes on the node control. We give an example of an architecture that is highly scalable while supporting low latency

Cited by 5 publications

References 12 publications

Advances in integrated photonic circuits for packet-switched interconnection

Advances in integrated photonic circuits for packet-switched interconnection

Optical Switching in Next Generation Data Centers

On the Performance of a Large-Scale Optical Packet Switch Under Realistic Data Center Traffic

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