COCONUT: Seamless scale-out of network elements

Soudeh Ghorbani, P. Brighten Godfrey

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


A key use of software-defined networking is to enable scaleout of network data plane elements. Naively scaling networking elements, however, can cause incorrect behavior. For example, we show that an IDS system which operates correctly as a single network element can erroneously and permanently block hosts when it is replicated. In this paper, we provide a system, COCONUT, for seamless scale-out of network forwarding elements; that is, an SDN application programmer can program to what functionally appears to be a single forwarding element, but which may be replicated behind the scenes. To do this, we identify the key property for seamless scale out, weak causality, and guarantee it through a practical and scalable implementation of vector clocks in the data plane. We prove that COCONUT enables seamless scale out of networking elements, i.e., the user-perceived behavior of any COCONUT element implemented with a distributed set of concurrent replicas is provably indistinguishable from its singleton implementation. Finally, we build a prototype of COCONUT and experimentally demonstrate its correct behavior. We also show that its abstraction enables a more efficient implementation of seamless scale-out compared to a naive baseline.

Original languageEnglish (US)
Title of host publicationProceedings of the 12th European Conference on Computer Systems, EuroSys 2017
PublisherAssociation for Computing Machinery, Inc
Number of pages16
ISBN (Electronic)9781450349383
StatePublished - Apr 23 2017
Event12th European Conference on Computer Systems, EuroSys 2017 - Belgrade, Serbia
Duration: Apr 23 2017Apr 26 2017

Publication series

NameProceedings of the 12th European Conference on Computer Systems, EuroSys 2017


Other12th European Conference on Computer Systems, EuroSys 2017


  • Consistency
  • Correctness
  • Network functions
  • One big switch
  • One-to-many mapping
  • Replication
  • Software defined networking
  • Virtualization
  • Weak causal consistency

ASJC Scopus subject areas

  • Computer Networks and Communications
  • Software
  • Information Systems
  • Hardware and Architecture
  • Control and Systems Engineering


Dive into the research topics of 'COCONUT: Seamless scale-out of network elements'. Together they form a unique fingerprint.

Cite this