Taming asymmetric network delays for clock synchronization using power grid voltage

Dima Rabadi, Rui Tan, David K.Y. Yau, Sreejaya Viswanathan

Research output: Chapter in Book/Report/Conference proceedingConference contribution

9 Scopus citations

Abstract

Many clock synchronization protocols based on message pass- ing, e.g., the Network Time Protocol (NTP), assume sym- metric network delays to estimate the one-way packet trans- mission time as half of the round-trip time. As a result, asymmetric network delays caused by either network con- gestion or malicious packet delays can cause significant syn-chronization errors. This paper exploits sinusoidal voltage signals of an alternating current (ac) power grid to tame the asymmetric network delays for robust and resilient clock synchronization. Our extensive measurements show that the voltage signals at geographically distributed locations in a city are highly synchronized. Leveraging calibrated voltage phases, we develop a new clock synchronization protocol, which we call Grid Time Protocol (GTP), that allows di- rect measurement of one-way packet transmission times be- tween its slave and master nodes, under an analytic condi- tion that can be easily verified in practice. The direct mea- surements render GTP resilient against asymmetric network delays under this condition. A prototype implementation of GTP, based on readily available ac/ac transformers and PC- grade sound cards as voltage signal sampling devices, main- tains sub-ms synchronization accuracy for two nodes 30 km apart, in the presence of malicious packet delays. We believe that GTP is suitable for grid-connected distributed systems that are currently served by NTP but desire higher resilience against network dynamics and packet delay attacks.

Original languageEnglish (US)
Title of host publicationASIA CCS 2017 - Proceedings of the 2017 ACM Asia Conference on Computer and Communications Security
PublisherAssociation for Computing Machinery, Inc
Pages874-886
Number of pages13
ISBN (Electronic)9781450349444
DOIs
StatePublished - Apr 2 2017
Event2017 ACM Asia Conference on Computer and Communications Security, ASIA CCS 2017 - Abu Dhabi, United Arab Emirates
Duration: Apr 2 2017Apr 6 2017

Publication series

NameASIA CCS 2017 - Proceedings of the 2017 ACM Asia Conference on Computer and Communications Security

Other

Other2017 ACM Asia Conference on Computer and Communications Security, ASIA CCS 2017
Country/TerritoryUnited Arab Emirates
CityAbu Dhabi
Period4/2/174/6/17

All Science Journal Classification (ASJC) codes

  • Computer Science Applications
  • Information Systems
  • Computer Networks and Communications
  • Software

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