Cloud Computing | Ramesh Govindan

Our research explores the design of data centers, develops systems to monitor cloud computing infrastructure, and understand the reliability and manageability of hyperscalars.

SIGCOMM
ZENITH: Towards A Formally Verified Highly-Available Control Plane

Pooria Namyar, Arvin Ghavidel, Mingyang Zhang, and 4 more authors

In Proceedings of the ACM SIGCOMM 2025 Conference, 2025

Abs Bib Link

Today, large-scale software-defined networks use microservice-based controllers. Bugs in these controllers can reduce network availability by making the data plane state inconsistent with the high-level intent. To recover from such inconsistencies, modern controllers periodically reconcile the state of all the switches with the desired intent. However, periodic reconciliation limits the availability and performance of the network at scale. We introduce Zenith, a microservice-based controller that avoids inconsistencies by design rather than always relying on recovery mechanisms. We have formally verified Zenith’s specifications and have proved that it ensures the network state will eventually be consistent with intent. We automatically generate Zenith’s code from its specification to minimize the likelihood of errors in the final implementation. Zenith’s guarantees and abstractions also enable developers to independently verify SDN applications and ensure end-to-end safety and correctness. Zenith resolves inconsistencies 5\texttimes faster than today’s designs and significantly improves availability.
@inproceedings{namyar.p.ghavidel.a.ea:zenith, author = {Namyar, Pooria and Ghavidel, Arvin and Zhang, Mingyang and Madhyastha, Harsha V. and Ravi, Srivatsan and Wang, Chao and Govindan, Ramesh}, title = {ZENITH: Towards A Formally Verified Highly-Available Control Plane}, booktitle = {Proceedings of the ACM SIGCOMM 2025 Conference}, year = {2025}, series = {SIGCOMM '25}, pages = {409–433}, address = {New York, NY, USA}, publisher = {Association for Computing Machinery}, isbn = {9798400715242}, url = {https://doi.org/10.1145/3718958.3750533}, doi = {10.1145/3718958.3750533}, numpages = {25}, keywords = {software defined networking, formal methods, availability}, topics = {dcn}, location = {S\~{a}o Francisco Convent, Coimbra, Portugal} }
SIGCOMM
Firefly: Scalable, Ultra-Accurate Clock Synchronization for Datacenters

Pooria Namyar, Yuliang Li, Weitao Wang, and 10 more authors

In Proceedings of the ACM SIGCOMM 2025 Conference, 2025

Abs Bib Link

Cloud-based financial exchanges require sub-10ns device-to-device clock synchronization accuracy while adhering to Coordinated Universal Time (UTC). Existing clock sync techniques struggle to meet this demand at scale and are vulnerable to clock drift, jitter, and path asymmetries. Firefly, a software-driven datacenter clock sync system, scalably, cost-effectively, and reliably achieves very high clock sync accuracy. It employs a distributed consensus algorithm on a random overlay graph to rapidly converge to a common time while applying gradual adjustments to device hardware clocks. To realize consistent sync-to-UTC (external sync) across devices while maintaining a stable device-to-device internal sync, Firefly uses a novel technique, layered synchronization, that decouples internal and external syncs. In a 248-machine Clos network, Firefly achieves sub-10ns device-to-device and ≤1μs device-to-UTC sync, and is resilient to time server failure and unstable clocks.
@inproceedings{namyar.p.li.y.ea:firefly, author = {Namyar, Pooria and Li, Yuliang and Wang, Weitao and Dukkipati, Nandita and Yap, Kk and Gong, Junzhi and Chen, Chen and Gao, Peixuan and Ray, Devdeep and Kumar, Gautam and Ma, Yidan and Govindan, Ramesh and Vahdat, Amin}, title = {Firefly: Scalable, Ultra-Accurate Clock Synchronization for Datacenters}, booktitle = {Proceedings of the ACM SIGCOMM 2025 Conference}, year = {2025}, series = {SIGCOMM '25}, pages = {434–452}, address = {New York, NY, USA}, publisher = {Association for Computing Machinery}, isbn = {9798400715242}, url = {https://doi.org/10.1145/3718958.3750502}, doi = {10.1145/3718958.3750502}, numpages = {19}, topics = {dcn}, keywords = {clock synchronization, financial exchange, UTC synchronization, path asymmetry, distributed consensus}, location = {S\~{a}o Francisco Convent, Coimbra, Portugal} }

ToN

Optimal Oblivious Routing With Concave Objectives for Structured Networks

K. Chitavisutthivong, S. Supittayapornpong, P. Namyar, and 3 more authors

IEEE/ACM Transactions on Networking, Apr 2023

Bib

@article{chitavisutthivong.k.supittayapornpong.s.ea:optimal,
  author = {Chitavisutthivong, K. and Supittayapornpong, S. and Namyar, P. and Zhang, M. and Yu, M. and Govindan, R.},
  journal = {IEEE/ACM Transactions on Networking},
  title = {Optimal Oblivious Routing With Concave Objectives for
  		  Structured Networks},
  year = {2023},
  volume = {},
  number = {01},
  issn = {1558-2566},
  pages = {1-13},
  keywords = {routing;topology;network
  		  topology;servers;throughput;optimization;ieee
  		  transactions},
  doi = {10.1109/TNET.2023.3264632},
  publisher = {IEEE Computer Society},
  address = {Los Alamitos, CA, USA},
  month = apr,
  topics = {dcn}
}

NSDI

CloudCluster: Unearthing the Functional Structure of a Cloud Service

Weiwu Pang, Sourav Panda, Jehangir Amjad, and 2 more authors

In 19th USENIX Symposium on Networked Systems Design and Implementation (NSDI 22), Apr 2022

Bib Link

@inproceedings{pang.w.panda.s.ea:cloudcluster,
  author = {Pang, Weiwu and Panda, Sourav and Amjad, Jehangir and Diot, Christophe and Govindan, Ramesh},
  title = {{CloudCluster}: Unearthing the Functional Structure of a
  		  Cloud Service},
  booktitle = {19th USENIX Symposium on Networked Systems Design and
  		  Implementation (NSDI 22)},
  year = {2022},
  isbn = {978-1-939133-27-4},
  address = {Renton, WA},
  pages = {1213--1230},
  url = {https://www.usenix.org/conference/nsdi22/presentation/pang},
  publisher = {USENIX Association},
  topics = {dcn}
}

SoCC
Quadrant: A Cloud-Deployable NF Virtualization Platform

Jianfeng Wang, Tamás Lévai, Zhuojin Li, and 3 more authors

In SoCC ’22: Proceedings of the ACM Symposium on Cloud Computing, Apr 2022

Abs Bib Link Slides

Network Functions (NFs) now touch a significant fraction of Internet traffic. The hope has been that software-based NF Virtualization (NFV) would enable rapid development of new NFs by vendors and leverage the power and economics of commodity computing infrastructure for NF deployment. To date, no cloud NFV systems achieve NF chaining, isolation, SLO-adherence, and scaling together with existing cloud computing infrastructure and abstractions, all while achieving generality, speed, and ease of deployment; these properties are taken for granted in other cloud contexts but unavailable for NF processing. We present Quadrant, an efficient and secure cloud-deployable NFV system, and show that Quadrant’s approach of adapting existing cloud infrastructure to support packet processing can achieve NF chaining, isolation, generality, and performance in NFV. Quadrant reuses common cloud infrastructure such as Kubernetes, cloud functions, the Linux kernel, NIC hardware, and switches. It enables easy NFV deployment while delivering up to double the performance per core compared to the state of the art.
@inproceedings{wang.j.lévai.t.ea:quadrant, title = {Quadrant: A Cloud-Deployable NF Virtualization Platform}, author = {Wang, Jianfeng and Lévai, Tamás and Li, Zhuojin and Vieira, Marcos A. M. and Govindan, Ramesh and Raghavan, Barath}, url = {https://dl.acm.org/doi/10.1145/3542929.3563471}, talk = {https://youtu.be/70_bUua5870}, year = {2022}, date = {2022-11-07}, booktitle = {SoCC '22: Proceedings of the ACM Symposium on Cloud Computing}, keywords = {NFV, cloud computing, SLO}, pubstate = {to appear}, tppubtype = {inproceedings}, topics = {dcn} }

Infocom

Optimal Oblivious Routing for Structured Networks

Sucha Supittayapornpong, Pooria Namyar, Mingyang Zhang, and 2 more authors

In IEEE INFOCOM 2022 - IEEE Conference on Computer Communications, Apr 2022

Bib Link

@inproceedings{supittayapornpong.s.namyar.p.ea:optimal,
  author = {Supittayapornpong, Sucha and Namyar, Pooria and Zhang, Mingyang and Yu, Minlan and Govindan, Ramesh},
  booktitle = {IEEE INFOCOM 2022 - IEEE Conference on Computer
  		  Communications},
  title = {Optimal Oblivious Routing for Structured Networks},
  year = {2022},
  pages = {1988-1997},
  doi = {10.1109/INFOCOM48880.2022.9796682},
  topics = {dcn}
}

SIGCOMM

A throughput-centric view of the performance of datacenter topologies

Pooria Namyar, Sucha Supittayapornpong, Mingyang Zhang, and 2 more authors

In ACM SIGCOMM 2021 Conference, Virtual Event, USA, August 23-27, 2021, Apr 2021

Bib Link

@inproceedings{namyar.p.supittayapornpong.s.ea:throughput-centric,
  author = {Namyar, Pooria and Supittayapornpong, Sucha and Zhang, Mingyang and Yu, Minlan and Govindan, Ramesh},
  editor = {Kuipers, Fernando A. and Caesar, Matthew C.},
  title = {A throughput-centric view of the performance of datacenter
  		  topologies},
  booktitle = {{ACM} {SIGCOMM} 2021 Conference, Virtual Event, USA,
  		  August 23-27, 2021},
  pages = {349--369},
  publisher = {{ACM}},
  year = {2021},
  url = {https://doi.org/10.1145/3452296.3472913},
  doi = {10.1145/3452296.3472913},
  timestamp = {Wed, 11 Aug 2021 15:56:33 +0200},
  topics = {dcn},
  biburl = {https://dblp.org/rec/conf/sigcomm/NamyarS0YG21.bib}
}

ArXiv

Gemini: Practical Reconfigurable Datacenter Networks with Topology and Traffic Engineering

Mingyang Zhang, Jianan Zhang, Rui Wang, and 3 more authors

CoRR, Apr 2021

Bib Link

@article{zhang.m.zhang.j.ea:gemini,
  author = {Zhang, Mingyang and Zhang, Jianan and Wang, Rui and Govindan, Ramesh and Mogul, Jeffrey C. and Vahdat, Amin},
  title = {Gemini: Practical Reconfigurable Datacenter Networks with
  		  Topology and Traffic Engineering},
  journal = {CoRR},
  volume = {abs/2110.08374},
  year = {2021},
  eprinttype = {arXiv},
  eprint = {2110.08374},
  timestamp = {Thu, 03 Feb 2022 07:26:25 +0100},
  biburl = {https://dblp.org/rec/journals/corr/abs-2110-08374.bib},
  bibsource = {dblp computer science bibliography, https://dblp.org},
  topics = {dcn}
}

SIGCOMM

Towards Highly Available Clos-Based WAN Routers

Sucha Supittayapornpong, Barath Raghavan, and Ramesh Govindan

Apr 2019

Bib Link

@conference{supittayapornpong.s.raghavan.b.ea:towards,
  title = {Towards Highly Available Clos-Based WAN Routers},
  author = {Supittayapornpong, Sucha and Raghavan, Barath and Govindan, Ramesh},
  url = {https://dl.acm.org/citation.cfm?id=3342086},
  year = {2019},
  date = {2019-08-19},
  booktitle = {ACM SIGCOMM Conference on Network Architectures and
  		  Protocols},
  pubstate = {published},
  topics = {dcn},
  tppubtype = {conference},
}

NSDI

Understanding Lifecycle Management Complexity of Datacenter Topologies

Mingyang Zhang, Radhika Niranjan Mysore, Sucha Supittayapornpong, and 1 more author

In 16th USENIX Symposium on Networked Systems Design and Implementation (NSDI), Apr 2019

Bib

@inproceedings{zhang.m.mysore.rn.ea:understanding,
  title = {Understanding Lifecycle Management Complexity of
  		  Datacenter Topologies},
  author = {Zhang, Mingyang and Mysore, Radhika Niranjan and Supittayapornpong, Sucha and Govindan, Ramesh},
  year = {2019},
  date = {2019-02-26},
  booktitle = {16th USENIX Symposium on Networked Systems Design and
  		  Implementation (NSDI)},
  pubstate = {published},
  topics = {dcn},
  tppubtype = {conference},
}