Optimal Consistent Network Updates in Polynomial Time

Černý, Pavol; Foster, Nate; Jagnik, Nilesh; McClurg, Jedidiah

doi:10.1007/978-3-662-53426-7_9

Cited by 17 publications

(11 citation statements)

References 20 publications

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“…First, FLIP is not necessarily advantageous for specific subsets of policies. For instance, more specialized and efficient algorithms [4], [33] have been recently proposed for the special case of updates solely admitting initial and final paths for every flow throughout the update (strong consistency).…”

Section: Discussionmentioning

confidence: 99%

Safe, Efficient, and Robust SDN Updates by Combining Rule Replacements and Additions

Vissicchio

Cittadini

2017

IEEE/ACM Trans. Networking

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Disruption-free updates are a key primitive to effectively operate SDN networks and maximize the benefits of their programmability. In this paper, we study how to implement this primitive safely (with respect to forwarding correctness and policies), efficiently (in terms of consumed network resources) and robustly to unpredictable factors like delayed message delivery and processing. First, we analyze the fundamental limitations of prior proposals, which either (i) progressively replace initial flow rules with new ones, or (ii) instruct switches to maintain both initial and final rules. Second, we show that safe, efficient and robust updates can be achieved by leveraging a more general approach. We indeed unveil a dualism between rule replacements and additions, that opens new degrees of freedom for supporting SDN updates. Third, we demonstrate how to build upon this dualism. We propose FLIP, an algorithm that computes operational sequences combining the efficiency of rule replacements with the applicability of rule additions. FLIP identifies constraints on rule replacements and additions that independently prevent safety violations from occurring during the update. Then, it explores the solution space by swapping constraints that prevent the same safety violations, until it reaches a satisfiable set of constraints. Fourth, we perform extensive simulations, showing that FLIP can significantly outperform prior work: In the average case, it guarantees a much higher success rate than algorithms only based on rule replacements, and massively reduces the memory overhead needed by techniques solely using rule additions.

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Section: Discussionmentioning

confidence: 99%

Safe, Efficient, and Robust SDN Updates by Combining Rule Replacements and Additions

Vissicchio

Cittadini

2017

IEEE/ACM Trans. Networking

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“…WayUp [67] ordered rule replacements WPE Polynomial Finishes in 4 rounds; Does not guarantee connectivity (e.g., for loops) MIP of [67] ordered rule replacements WPE Exponential Optimizes update time; Guarantees absence of loops MIP of [63] ordered rule replacements WPE chains Exponential Optimizes update time; Guarantees absence of loops [84], [85, §2] ordered rule replacements arbitrary Exponential Update synthesis based on linear temporal logic and model checking [86] ordered rule replacements PPC Polynomial Algorithm based on necessary conditions for PPC-preserving switch updates; Minimizes update rounds GPIA [87] ordered rule replacements PPC Polynomial Greedy algorithm; Minimizes update rounds; Applicable to hybrid SDNs (becomes exponential)…”

Section: B Algorithms and Complexitymentioning

confidence: 99%

Survey of Consistent Software-Defined Network Updates

Foerster

Schmid

Vissicchio

2019

IEEE Commun. Surv. Tutorials

117

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Computer networks have become a critical infrastructure. In fact, networks should not only meet strict requirements in terms of correctness, availability, and performance, but they should also be very flexible and support fast updates, e.g., due to policy changes, increasing traffic, or failures. This paper presents a structured survey of mechanism and protocols to update computer networks in a fast and consistent manner. In particular, we identify and discuss the different desirable consistency properties that should be provided throughout a network update, the algorithmic techniques which are needed to meet these consistency properties, and the implications on the speed and costs at which updates can be performed. We also explain the relationship between consistent network update problems and classic algorithmic optimization ones. While our survey is mainly motivated by the advent of Software-Defined Networks (SDNs) and their primary need for correct and efficient update techniques, the fundamental underlying problems are not new, and we provide a historical perspective of the subject as well.

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“…We refer to [21] for an introduction to SDN. Solutions for correctness of updates of software-defined networks include consistent updates [7,28], dynamic scheduling [17], and incremental updates [18]. Both explicit and SMT-based model checking [1,5,22,23,26,31] is used to verify software-defined networks.…”

Section: Related Workmentioning

confidence: 99%

AdamMC: A Model Checker for Petri Nets with Transits against Flow-LTL

Finkbeiner

Gieseking

Hecking-Harbusch

et al. 2020

Computer Aided Verification

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The correctness of networks is often described in terms of the individual data flow of components instead of their global behavior. In software-defined networks, it is far more convenient to specify the correct behavior of packets than the global behavior of the entire network. Petri nets with transits extend Petri nets and Flow-LTL extends LTL such that the data flows of tokens can be tracked. We present the tool AdamMC as the first model checker for Petri nets with transits against Flow-LTL. We describe how AdamMC can automatically encode concurrent updates of software-defined networks as Petri nets with transits and how common network specifications can be expressed in Flow-LTL. Underlying AdamMC is a reduction to a circuit model checking problem. We introduce a new reduction method that results in tremendous performance improvements compared to a previous prototype. Thereby, AdamMC can handle software-defined networks with up to 82 switches.

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Optimal Consistent Network Updates in Polynomial Time

Cited by 17 publications

References 20 publications

Safe, Efficient, and Robust SDN Updates by Combining Rule Replacements and Additions

Safe, Efficient, and Robust SDN Updates by Combining Rule Replacements and Additions

Survey of Consistent Software-Defined Network Updates

AdamMC: A Model Checker for Petri Nets with Transits against Flow-LTL

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