### Abstract

A consistent update installs a new packet-forwarding policy across the switches of a software-defined network in place of an old policy. While doing so, such an update guarantees that every packet entering the network either obeys the old policy or the new one, but not some combination of the two. In this paper, we introduce new algorithms that trade the time required to perform a consistent update against the rule-space overhead required to implement it. We break an update in to k rounds that each transfer part of the traffic to the new configuration. The more rounds used, the slower the update, but the smaller the rule-space overhead. To ensure consistency, our algorithm analyzes the dependencies between rules in the old and new policies to determine which rules to add and remove on each round. In addition, we show how to optimize rule space used by representing the minimization problem as a mixed integer linear program. Moreover, to ensure the largest flows are moved first, while using rule space efficiently, we extend the mixed integer linear program with additional constraints. Our initial experiments show that a 6-round, optimized incremental update decreases rule space overhead from 100% to less than 10%. Moreover, if we cap the maximum rule-space overhead at 5% and assume the traffic flow volume follows Zipf's law, we find that 80% of the traffic may be transferred to the new policy in the first round and 99% in the first 3 rounds.

Original language | English (US) |
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Title of host publication | HotSDN 2013 - Proceedings of the 2013 ACM SIGCOMM Workshop on Hot Topics in Software Defined Networking |

Pages | 49-54 |

Number of pages | 6 |

DOIs | |

State | Published - Sep 16 2013 |

Event | 2013 2nd ACM SIGCOMM Workshop on Hot Topics in Software Defined Networking, HotSDN 2013 - Hong Kong, China Duration: Aug 16 2013 → Aug 16 2013 |

### Publication series

Name | HotSDN 2013 - Proceedings of the 2013 ACM SIGCOMM Workshop on Hot Topics in Software Defined Networking |
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### Other

Other | 2013 2nd ACM SIGCOMM Workshop on Hot Topics in Software Defined Networking, HotSDN 2013 |
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Country | China |

City | Hong Kong |

Period | 8/16/13 → 8/16/13 |

### All Science Journal Classification (ASJC) codes

- Computer Networks and Communications
- Software

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## Cite this

*HotSDN 2013 - Proceedings of the 2013 ACM SIGCOMM Workshop on Hot Topics in Software Defined Networking*(pp. 49-54). (HotSDN 2013 - Proceedings of the 2013 ACM SIGCOMM Workshop on Hot Topics in Software Defined Networking). https://doi.org/10.1145/2491185.2491191