Reliable and Cost Efficient Passive Optical Interconnects for Data Centers

Cheng, Yuxin; Fiorani, Matteo; Wosinska, Lena; Chen, Jiajia

doi:10.1109/lcomm.2015.2478474

Cited by 20 publications

(12 citation statements)

References 11 publications

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“…In [21] and [22] we proposed several passive optical ToR interconnect architectures for the access tier in DCs. These architectures use passive optical components (i.e., arrayed waveguide grating (AWG) and/or optical couplers) to interconnect the servers in the rack.…”

Section: Related Workmentioning

confidence: 99%

“…It has been demonstrated that the passive optical components offer cost and power saving as well as high reliability. While in [21] and [22] we focused on the data plane architecture, in [18] we proposed a MAC protocol and novel DBA algorithms to achieve efficient bandwidth utilization in POTORI. The current paper extends our previous work by covering both data and control plane, and provides a complete design of POTORI architecture along with a detailed analysis of the network performance and an extensive comparison with the conventional EPS solutions.…”

Section: Related Workmentioning

confidence: 99%

“…The POTORI data plane was proposed and introduced in our previous work [22]. The key component of POTORI data plane is an (N+1)⇥(N+1) passive coupler that acts as the switching fabric to interconnect all the servers in the rack.…”

Section: Data Planementioning

confidence: 99%

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POTORI: A Passive Optical Top-of-Rack Interconnect Architecture for Data Centers

Cheng¹,

Fiorani²,

Lin³

et al. 2017

J. Opt. Commun. Netw.

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Abstract-Several optical interconnect architectures inside data centers (DCs) have been proposed to efficiently handle the rapidly growing traffic demand. However, not many works have tackled the interconnects at top-of-rack (ToR), which have a large impact on the performance of the data center networks (DCNs) and can introduce serious scalability limitations due to the high cost and power consumption. In this paper, we propose a passive optical ToR interconnect architecture (POTORI) to replace the conventional electronic packet switch (EPS) in the access tier of DCNs. In the data plane, POTORI relies on a passive optical coupler to interconnect the servers within the rack and the interfaces toward the aggregation/core tiers. The POTORI control plane is based on a centralized rack controller responsible for managing the communications among the servers in the rack. We propose a cycle-based medium access control (MAC) protocol to efficiently manage the exchange of control messages and the data transmission inside the rack. We also introduce and evaluate a dynamic bandwidth allocation (DBA) algorithm for POTORI, namely Largest First (LF). Extensive simulation results show that, with the use of fast tunable optical transceivers, POTORI and the proposed LF strategy are able to achieve an average packet delay below 10 µs under realistic DC traffic scenarios, which outperforms conventional EPSs. On the other hand, with slower tunable optical transceivers, a careful configuration of the network parameters (e.g., maximum cycletime of the MAC protocol) is necessary to obtain a good network performance in terms of the average packet delay.Index Terms-Optical interconnect architectures, data center networks, medium access control (MAC), dynamic bandwidth allocation (DBA).

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Section: Related Workmentioning

confidence: 99%

Section: Related Workmentioning

confidence: 99%

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POTORI: A Passive Optical Top-of-Rack Interconnect Architecture for Data Centers

Cheng¹,

Fiorani²,

Lin³

et al. 2017

J. Opt. Commun. Netw.

Self Cite

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“…The gain in energy consumption increases when a higher data rate on a per-server basis is considered [2]. Apart from the advantages of capacity and energy consumption, the coupler-based ToR interconnect can also offer high reliability and cost efficiency [4] thanks to its passive manner. However, the design of existing couplerbased POI architectures [1-4] does not consider the physical layer impairments which may significantly affect the quality of the signals.…”

Section: Introductionmentioning

confidence: 99%

“…Apart from the advantages of capacity and energy consumption, the coupler-based ToR interconnect can also offer high reliability and cost efficiency [4] thanks to its passive manner. However, the design of existing couplerbased POI architectures [1][2][3][4] does not consider the physical layer impairments which may significantly affect the quality of the signals. If the received signal power fails to reach the receiver sensitivity threshold, the transmitted data cannot be detected.…”

Section: Introductionmentioning

confidence: 99%

To Overcome the Scalability Limitation of Passive Optical Interconnects in Datacentres

Lin

Szczerba

Agrell

et al. 2016

Asia Communications and Photonics Conference 2016

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Abstract:We propose to add optical amplifier(s) to passive optical interconnect (POI) at top-of-rack in datacentres and validate this approach by introducing impairment constraints into POIs design. It is shown that one amplifier can improve scalability by a factor of 16. IntroductionThe volume of datacentre traffic is ever-growing, causing a serious bottleneck in terms of bandwidth and energy consumption. To address this problem, optical communication and switching techniques are introduced in datacentres. However, commodity switches are still widely used at the top-of-rack (ToR). They consume a lot of energy and also limit capacity upgrading. Therefore, a coupler-based passive optical interconnect (POI) has been proposed [1-3] to replace the commodity switch at ToR, leading to an overall reduction of energy consumption of switching equipment in datacentres by a factor of 10. The gain in energy consumption increases when a higher data rate on a per-server basis is considered [2]. Apart from the advantages of capacity and energy consumption, the coupler-based ToR interconnect can also offer high reliability and cost efficiency [4] thanks to its passive manner. However, the design of existing couplerbased POI architectures [1-4] does not consider the physical layer impairments which may significantly affect the quality of the signals. If the received signal power fails to reach the receiver sensitivity threshold, the transmitted data cannot be detected. As a result, the reserved resources are wasted. Therefore, it is of key importance to take the physical layer impairments into account and analyze their impact on the feasibility of the POI architectures. In this paper, we focus on the intra-rack communications. A thorough analysis of physical layer impairments is carried out considering the coupler-based POI at ToR in order to quantify its scalability. It has been shown that with introduction of an optical amplifier to increase the optical power budget, the interconnect size can be increased by a factor of more than 10, making it possible to meet the scalability requirement at ToR [5]. Passive optical interconnect architectureThe authors of [2,4] proposed a POI architecture based on an Nx2 coupler, as shown in Fig. 1(a). It takes advantage of the high capacity of the dense wavelength division multiplexing (DWDM) technique and the broadcast-and-select nature of optical couplers to handle the bursty and multicast traffic in datacentres. In this approach, the optical network interfaces (ONIs) are dedicated to each server and connected to the side of the coupler with N ports. The transmitted signals pass through the coupler and are selected by a wavelength selective switch (WSS) according to whether the destination is inside or outside the rack. For the intra-rack traffic (see the red arrow in Fig. 1), the signals are looped back via an isolator (ISO) to the coupler and broadcast to all the servers. The optical tunable filter (OTF) at the receiver selects the wavelength of interests and the signal is detected by a p...

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Modeling the failures of power‐aware data centers by leveraging heat recirculation

Feng

Deng

2019

Concurrency and Computation

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Summary With the explosive growth of data, hundreds of thousands of servers may be contained in a single data center. Hence, node failures are unavoidable and generally negatively effects the performance of the whole data center. Additionally, data centers with a large number of nodes will cause plenty of energy consumption. Many existing task scheduling techniques can effectively reduce the power consumption in data centers by considering heat recirculation. However, the traditional techniques do not take the situation of node failures into account. This paper proposes an airflow‐based failure model for data centers by leveraging heat recirculation. In this model, the spatial distribution and time distribution of failures are considered. Furthermore, a genetic algorithm (GA) and a simulated annealing algorithm (SA) are implemented to evaluate the proposed failure model. Because the positions of node failures have a significant impact on the heat recirculation and the energy consumption of data centers, failures with different positions are analyzed and evaluated. The experimental results demonstrate that the energy consumption of data centers can be significantly reduced by using the GA and SA algorithms for task scheduling based on the proposed failure model.

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Reliable and Cost Efficient Passive Optical Interconnects for Data Centers

Cited by 20 publications

References 11 publications

POTORI: A Passive Optical Top-of-Rack Interconnect Architecture for Data Centers

POTORI: A Passive Optical Top-of-Rack Interconnect Architecture for Data Centers

To Overcome the Scalability Limitation of Passive Optical Interconnects in Datacentres

Modeling the failures of power‐aware data centers by leveraging heat recirculation

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