Transiently Consistent SDN Updates: Being Greedy is Hard

  • Saeed Akhoondian Amiri
  • Arne Ludwig
  • Jan Marcinkowski
  • Stefan Schmid
Conference paper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 9988)


The software-defined networking paradigm introduces interesting opportunities to operate networks in a more flexible yet formally verifiable manner. Despite the logically centralized control, however, a Software-Defined Network (SDN) is still a distributed system, with inherent delays between the switches and the controller. Especially the problem of changing network configurations in a consistent manner, also known as the consistent network update problem, has received much attention over the last years. This paper revisits the problem of how to update an SDN in a transiently consistent, loop-free manner. First, we rigorously prove that computing a maximum (“greedy”) loop-free network update is generally NP-hard; this result has implications for the classic maximum acyclic subgraph problem (the dual feedback arc set problem) as well. Second, we show that for special problem instances, fast and good approximation algorithms exist.


Problem Instance Greedy Approach Forward Edge Legal Network Forwarding Rule 
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Copyright information

© Springer International Publishing AG 2016

Authors and Affiliations

  • Saeed Akhoondian Amiri
    • 1
  • Arne Ludwig
    • 1
  • Jan Marcinkowski
    • 2
  • Stefan Schmid
    • 3
  1. 1.Technical University BerlinBerlinGermany
  2. 2.University of WroclawWroclawPoland
  3. 3.Aalborg UniversityAalborgDenmark

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