A survey on high-precision time synchronization techniques for optical datacenter networks and a zero-overhead microsecond-accuracy solution

Ahmed, Tanjila; Rahman, Sabidur; Tornatore, Massimo; Kim, Kwangjoon; Mukherjee, Biswanath

doi:10.1007/s11107-018-0773-9

Cited by 11 publications

(5 citation statements)

References 20 publications

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“…In [83], a synchronization approach for data centers is presented, with the focus on optical networks. The approach is not compliant with the standards, a sum or RTT is used for estimation, and an accuracy below 7µs is achieved (using simulation).…”

Section: Wired Approaches Using Rtt-based Estimationmentioning

confidence: 99%

Estimators for Time Synchronization—Survey, Analysis, and Outlook

Puttnies

Danielis

Sharif

et al. 2020

IoT

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Time (or clock) synchronization is a large and vital field of research, as synchronization is a precondition for many applications. A few example applications are distributed data acquisition, distributed databases, and real-time communication. First, this survey paper introduces the research area of time synchronization and emphasizes its relation to other research areas. Second, we give an overview of the state-of-the-art of time synchronization. Herein, we discuss both established protocol and research approaches. We analyze all techniques according to three criteria: used estimation algorithm, achievable synchronization accuracy, and the experimental conditions. In our opinion, this analysis highlights potential improvements. The most important question in this survey is as follows: which estimation method can be used to achieve which accuracies under which conditions? The intention behind this is to identify estimation methods that are particularly worth considering, as these already achieve good results in the wireless area but have not yet been examined in the wired area (and vice versa). This survey paper differs from other surveys in particular through the consideration of wireless and wired synchronization and the focus on estimation algorithms and their achievable accuracy.

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Section: Wired Approaches Using Rtt-based Estimationmentioning

confidence: 99%

Estimators for Time Synchronization—Survey, Analysis, and Outlook

Puttnies

Danielis

Sharif

et al. 2020

IoT

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“…In [18], authors use PTP to synchronize a packet-switched optical network for datacenters, with zero-overhead. Zerooverhead is achieved by using data packets to carry the time messages instead of a separate control channel.…”

Section: Related Workmentioning

confidence: 99%

Globally Synchronized Time via Datacenter Networks

Shrivastav

Lee

Wang

et al. 2019

IEEE/ACM Trans. Networking

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Synchronized time is critical to distributed systems and network applications in a datacenter network. Unfortunately, many clock synchronization protocols in datacenter networks such as NTP and PTP are fundamentally limited by the characteristics of packet-switched networks. In particular, network jitter, packet buffering and scheduling in switches, and network stack overheads add non-deterministic variances to the round trip time, which must be accurately measured to synchronize clocks precisely. We present the Datacenter Time Protocol (DTP), a clock synchronization protocol that does not use packets at all, but is able to achieve nanosecond precision. In essence, the DTP uses the physical layer of network devices to implement a decentralized clock synchronization protocol. By doing so, the DTP eliminates most non-deterministic elements in clock synchronization protocols and has virtually zero protocol overhead since it does not add load at layer-2 or higher at all. It does require replacing network devices, which can be done incrementally and with very small amount of hardware resource consumption. We demonstrate that the precision provided by DTP in hardware is bounded by 4TD where D is the longest distance between any two nodes in a network in terms of number of hops and T is the period of the fastest clock. The precision can be further improved by combining DTP with frequency synchronization. By contrast, the precision of the state-of-theart protocol (PTP) is not bounded: The precision is hundreds of nanoseconds in an idle network and can decrease to hundreds of microseconds in a heavily congested network.

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“…With the advent of 5G [1] and internet of things (IoT) based applications [9], time synchronization between the sensors and actuators has become all the more important [10]. The recent advances in digitization and big data consumption by the masses have accelerated the adoption of data centers and cloud computing, which works on the accurate track of time across a distributed network of systems [11].…”

Section: Introductionmentioning

confidence: 99%

Indian Standard Time Dissemination Using Precision Time Protocol: Toward Resilient Time Synchronization Using Optical Fibers for Critical Infrastructure in India

Kumar,

Ghosh,

Neelam

et al. 2024

MAPAN

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National time dissemination using terrestrial ethernet and optical fiber cables is an alternative to satellite-based systems and provides redundancy to reliable time services for critical infrastructure in the country. Precision time protocol based on IEEE 1588 standards using such cables and fibers can provide sub-microsecond time synchronization between a provider and the client. The method employs hardware time stamping, dedicated traffic-free fiber links, and PTP-aware network elements. We present a proof of concept experiment for the distribution of Indian standard time using the IEEE protocol in a laboratory and the effect of introducing a PTP-supported switch on the distribution performance. Further, we report on the observed synchronization when an underground dark telecom optical fiber lying outside the laboratory in the central Delhi region, is used as the medium of communication. The one-second pulse-pulse jitter is found to be within 2.5 ns.

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A survey on high-precision time synchronization techniques for optical datacenter networks and a zero-overhead microsecond-accuracy solution

Cited by 11 publications

References 20 publications

Estimators for Time Synchronization—Survey, Analysis, and Outlook

Estimators for Time Synchronization—Survey, Analysis, and Outlook

Globally Synchronized Time via Datacenter Networks

Indian Standard Time Dissemination Using Precision Time Protocol: Toward Resilient Time Synchronization Using Optical Fibers for Critical Infrastructure in India

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