Elmo: Source routed multicast for public clouds

Muhammad Shahbaz, Lalith Suresh, Jennifer L. Rexford, Nicholas G. Feamster, Ori Rottenstreich, Mukesh Hira

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

11 Scopus citations

Abstract

We present Elmo, a system that addresses the multicast scalability problem in multi-tenant datacenters. Modern cloud applications frequently exhibit one-to-many communication patterns and, at the same time, require sub-millisecond latencies and high throughput. IP multicast can achieve these requirements but has controland data-plane scalability limitations that make it challenging to offer it as a service for hundreds of thousands of tenants, typical of cloud environments. Tenants, therefore, must rely on unicast-based approaches (e.g., application-layer or overlay-based) to support multicast in their applications, imposing bandwidth and end-host CPU overheads, with higher and unpredictable latencies. Elmo scales network multicast by taking advantage of emerging programmable switches and the unique characteristics of datacenter networks; specifically, the hypervisor switches, symmetric topology, and short paths in a datacenter. Elmo encodes multicast group information inside packets themselves, reducing the need to store the same information in network switches. In a three-tier data-center topology with 27,000 hosts, Elmo supports a million multicast groups using an average packet-header size of 114 bytes, requiring as few as 1,100 multicast group-table entries on average in leaf switches, and having a traffic overhead as low as 5% over ideal multicast.

Original languageEnglish (US)
Title of host publicationSIGCOMM 2019 - Proceedings of the 2019 Conference of the ACM Special Interest Group on Data Communication
PublisherAssociation for Computing Machinery, Inc
Pages458-471
Number of pages14
ISBN (Electronic)9781450359566
DOIs
StatePublished - Aug 19 2019
Event50th Conference of the ACM Special Interest Group on Data Communication, SIGCOMM 2019 - Beijing, China
Duration: Aug 19 2019Aug 23 2019

Publication series

NameSIGCOMM 2019 - Proceedings of the 2019 Conference of the ACM Special Interest Group on Data Communication

Conference

Conference50th Conference of the ACM Special Interest Group on Data Communication, SIGCOMM 2019
Country/TerritoryChina
CityBeijing
Period8/19/198/23/19

All Science Journal Classification (ASJC) codes

  • Computer Networks and Communications
  • Signal Processing
  • Electrical and Electronic Engineering
  • Communication

Keywords

  • Bitmap encoding
  • Multicast
  • P4
  • PISA
  • PISCES
  • Programmable parsing
  • Source routing

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