Can't Touch This: Consistent Network Updates for Multiple Policies

Dudycz, Szymon; Ludwig, Arne; Schmid, Stefan

doi:10.1109/dsn.2016.21

Cited by 36 publications

(21 citation statements)

References 31 publications

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“…One first line of research focuses on providing additional guarantees, e.g., congestion-freedom (from [53] to [54], [55], [56], [57], [58], [59], [60]). In a second line of research, several algorithms [32], [61], [62], [63], [64] to compute a set of ordered rule replacements have been proposed to deal with specific SDN update cases (e.g., where only forwarding consistency is needed), avoiding the need for additional rules and hence enabling more resource-efficient approaches (e.g., TCAM memory slots are expensive and precious).…”

Section: Sdn Controllermentioning

confidence: 99%

“…c) Other objectives: Dudycz et al [61], detailed in [71], initiated the study of how to update multiple policies simultaneously, in a loop-free manner. In their approach, the authors aim to minimize the number of so-called touches: the total number of update messages the switches receive from the controller.…”

Section: A Guaranteeing Loop-freedommentioning

confidence: 99%

“…Notwithstanding, Dudycz et al [61] also present optimal polynomial-time algorithms to combine consistent update schedules computed for individual policies (e.g., using any existing algorithm, e.g., [64], [65]), into a global schedule guaranteeing a minimal number of touches. This optimal merging algorithm is not limited to loop-free updates, but applies to any consistency property: if the consistency property holds for individual policies, then it also holds in the joint schedule minimizing the number of touches.…”

Section: A Guaranteeing Loop-freedommentioning

confidence: 99%

See 2 more Smart Citations

Survey of Consistent Software-Defined Network Updates

Foerster

Schmid

Vissicchio

2019

IEEE Commun. Surv. Tutorials

Self Cite

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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Section: Sdn Controllermentioning

confidence: 99%

Section: A Guaranteeing Loop-freedommentioning

confidence: 99%

Section: A Guaranteeing Loop-freedommentioning

confidence: 99%

See 1 more Smart Citation

Survey of Consistent Software-Defined Network Updates

Foerster

Schmid

Vissicchio

2019

IEEE Commun. Surv. Tutorials

Self Cite

117

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“…Dudycz et al [3] show that simultaneously computing two network updates while requiring a minimal number of switch updates ("touches") is NP-hard. Brandt et al [2] give a polynomial algorithm to decide if congestion-free update is possible when flows are "splittable" and/or not restricted to be integer.…”

Section: Related Workmentioning

confidence: 99%

Optimal Consistent Network Updates in Polynomial Time

Černý

Foster

Jagnik

et al. 2016

Lecture Notes in Computer Science

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Abstract. Software-defined networking (SDN) allows operators to control the behavior of a network by programatically managing the forwarding rules installed on switches. However, as is common in distributed systems, it can be difficult to ensure that certain consistency properties are preserved during periods of reconfiguration. The widely-accepted notion of per-packet consistency requires every packet to be forwarded using the new configuration or the old configuration, but not a mixture of the two. If switches can be updated in some (partial) order which guarantees that per-packet consistency is preserved, we call this order a consistent order update. In particular, switches that are incomparable in this order can be updated in parallel. We call a consistent order update optimal if it allows maximal parallelism. This paper presents a polynomial-time algorithm for finding an optimal consistent order update. This contrasts with other recent results in the literature, which show that for other classes of properties (e.g., loop-freedom and waypoint enforcement), the optimal update problem is NP-complete.

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“…Therefore, synchronicity and consistency is ensured avoiding out of order updates and ensuring waypoint enforcement [5], weak loop freedom [4]. More work on multiple policies can be found on [1] [3].…”

Section: Introductionmentioning

confidence: 99%

Towards Transiently Secure Updates in Asynchronous SDNs

Shukla

Schmid

Feldmann

et al. 2016

Proceedings of the 2016 ACM SIGCOMM Conference

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Software-Defined Networks (SDNs) promise to overcome the often complex and error-prone operation of traditional computer networks, by enabling programmability, automation and verifiability. Yet, SDNs also introduce new challenges, for example due to the asynchronous communication channel between the logically centralized control platform and the switches in the data plane. In particular, the asynchronous communication of network update commands (e.g., OpenFlow FlowMod messages) may lead to transient inconsistencies, such as loops or bypassed waypoints (e.g., firewalls). One approach to ensure transient consistency even in asynchronous environments is to employ smart scheduling algorithms: algorithms which update subsets of switches in each communication round only, where each subset in itself guarantees consistency. In this demo, we show how to change routing policies in a transiently consistent manner. We demonstrate two algorithms, namely, Wayup [5] and Peacock [4], which partition the network updates sent from SDN controller towards OpenFlow software switches into multiple rounds as per respective algorithms. Later, the barrier messages are utilized to ensure reliable network updates.

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Can't Touch This: Consistent Network Updates for Multiple Policies

Cited by 36 publications

References 31 publications

Survey of Consistent Software-Defined Network Updates

Survey of Consistent Software-Defined Network Updates

Optimal Consistent Network Updates in Polynomial Time

Towards Transiently Secure Updates in Asynchronous SDNs

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