Hybrid fat-tree: extending fat-tree to exploit optical switch transparency with WDM

G. Guelbenzu, N. Calabretta, O. Raz

Research output: Contribution to journalArticleAcademicpeer-review

2 Citations (Scopus)
3 Downloads (Pure)


Data center networks are the underlying infrastructure supporting the exponential growth of cloud services. Several data center network architectures based on electronic switches or on a combination of electronic and optical switches have been suggested in order to cope with ever-increasing demands. However, a common analytic model describing the network architectures in terms of servers, switches, transceivers, and fibers is lacking. Hence, a true comparison of the scaling in power consumption and cost between different topologies is difficult. This work presents a mathematical framework defining electronic and hybrid topologies under the same model parameters. It explores how the introduction of wavelength-division multiplexing (WDM) and optical switches in Fat-Tree like topologies impact their scaling. We find that these technologies reduce the required number of switches by 45%, transceivers by 60%, and fibers by 50% in the minimum hybrid networks. In such networks, our real case scenario study based on 25G technologies available at present predicts power savings of at least 55% and cost savings of at least 48%. On top of that, larger savings are foreseen when increased port-density transceivers become available.

Original languageEnglish
Pages (from-to)89-101
Number of pages13
JournalOptical Fiber Technology
Publication statusPublished - 1 Aug 2018


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