HULA: Scalable load balancing using programmable data planes

Naga Katta, Mukesh Hira, Changhoon Kim, Anirudh Sivaraman, Jennifer L. Rexford

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

217 Scopus citations


Datacenter networks employ multi-rooted topologies (e.g., LeafSpine, Fat-Tree) to provide large bisection bandwidth. These topologies use a large degree of multipathing, and need a data-plane loadbalancing mechanism to effectively utilize their bisection bandwidth. The canonical load-balancing mechanism is equal-cost multipath routing (ECMP), which spreads traffic uniformly across multiple paths. Motivated by ECMP's shortcomings, congestion-aware load-balancing techniques such as CONGA have been developed. These techniques have two limitations. First, because switch memory is limited, they can only maintain a small amount of congestiontracking state at the edge switches, and do not scale to large topologies. Second, because they are implemented in custom hardware, they cannot be modified in the field. This paper presents HULA, a data-plane load-balancing algorithm that overcomes both limitations. First, instead of having the leaf switches track congestion on all paths to a destination, each HULA switch tracks congestion for the best path to a destination through a neighboring switch . Second, we design HULA for emerging programmable switches and program it in P4 to demonstrate that HULA could be run on such programmable chipsets, without requiring custom hardware. We evaluate HULA extensively in simulation, showing that it outperforms a scalable extension to CONGA in average flow completion time (1.6× at 50% load, 3× at 90% load).

Original languageEnglish (US)
Title of host publicationSymposium on Software Defined Networking (SDN) Research, SOSR 2016
PublisherAssociation for Computing Machinery, Inc
ISBN (Electronic)9781450334518
StatePublished - Mar 14 2016
EventSymposium on Software Defined Networking (SDN) Research, SOSR 2016 - Santa Clara, United States
Duration: Mar 14 2016Mar 15 2016

Publication series

NameSymposium on Software Defined Networking (SDN) Research, SOSR 2016


OtherSymposium on Software Defined Networking (SDN) Research, SOSR 2016
Country/TerritoryUnited States
CitySanta Clara

All Science Journal Classification (ASJC) codes

  • Computer Networks and Communications
  • Software


  • In-Network Load Balancing
  • Network Congestion
  • Programmable Switches
  • Scalability


Dive into the research topics of 'HULA: Scalable load balancing using programmable data planes'. Together they form a unique fingerprint.

Cite this