Churn- and DoS-resistant Overlay Networks Based on Network Reconfiguration

Drees, Maximilian; Gmyr, Robert; Scheideler, Christian

doi:10.1145/2935764.2935783

Cited by 11 publications

(22 citation statements)

References 30 publications

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“…In fact, variations of our notion of committees have been employed in building overlays for over 15 years (for example, see Fiat and Saia [16]). Over the years, we have seen quite a few variations spanning both deterministic [26] and randomized overlay networks [4,13]. However, our design allows us to provide a DHT solution that can be constructed quickly.…”

Section: Our Results and Technical Contributionsmentioning

confidence: 99%

“…Adversary's characteristics. Our protocols operate against an almost adaptive adversary that subsumes the power of adversaries employed in both [7] and [13]. We say that an adversary is t-late omniscient if, at each round r, it is aware of all the algorithmic activities (including the random bits employed by the algorithm) from round 1 up to round r − t, but is oblivious to the execution and random bits employed by the algorithm from round r − t + 1 onward.…”

Section: Network Model and Problem Statementmentioning

confidence: 99%

“…In contrast, [7] employs the weaker oblivious adversary, but, like ours, its actions are instantaneous. The adversary in [13] is also Θ(log log n)-late omniscient, but its actions are not instantaneous. Any changes to the network (both inserting and deleting nodes) must be announced to the protocol Θ(log log n)-rounds before the change occurs.…”

Section: Network Model and Problem Statementmentioning

confidence: 99%

“…We now show how each committee in Spartan can obtain the CMLs of Θ(log n) uniformly and independently chosen committees using random walks. Normally, the random walks would require O(log n) steps to reach a random node, but we adapt the well-known pointer doubling technique [22,13] to our context to achieve an exponential speedup of O(log log n) steps. The steps are described in Algorithm 2 under the assumption that Spartan is robust during its execution, which is reasonable because the sampling procedure is designed to work in tandem with the maintenance protocol that will guarantee robustness.…”

Section: Random Walks Based Samplingmentioning

confidence: 99%

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Spartan: A Framework For Sparse Robust Addressable Networks

Augustine

Sivasubramaniam

2018

2018 IEEE International Parallel and Distributed Processing Symposium (IPDPS)

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A Peer-to-Peer (P2P) network is a dynamic collection of nodes that connect with each other via virtual overlay links built upon an underlying network (usually, the Internet). Typical P2P networks, however, are highly dynamic and can experience very heavy churn, i.e., a large number of nodes join/leave the network every time step. Building and maintaining a stable overlay network despite such heavy churn is therefore an important problem that has been studied extensively for nearly two decades.We present an overlay design called Sparse Robust Addressable Network (Spartan) that can tolerate heavy adversarial churn. We show that Spartan can be built efficiently in a fully distributed manner within O(log n) rounds. Furthermore, the Spartan overlay structure can be maintained, again, in a fully distributed manner despite adversarially controlled churn (i.e., nodes joining and leaving) and significant variation in the number of nodes. When the number of nodes in the network lies in [n, f n] for any fixed f ≥ 1 the adversary can remove up to n nodes and add up to n nodes (for some small but fixed > 0) within any period of P rounds for some P ∈ O(log log n). Moreover, the adversary can add or remove nodes from the network at will and without any forewarning.Despite such uncertainty in the network, Spartan maintains Θ(n/ log n) committees that are stable and addressable collections of Θ(log n) nodes each. Any node that enters the network will be able to gain membership in one of these committees within O(1) rounds. The committees are also capable of performing sustained computation and passing messages between each other. Thus, any protocol designed for static networks can be simulated on Spartan with minimal overhead. This makes Spartan an ideal platform for developing applications. All our results hold with high probability. *

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Section: Our Results and Technical Contributionsmentioning

confidence: 99%

Section: Network Model and Problem Statementmentioning

confidence: 99%

Section: Network Model and Problem Statementmentioning

confidence: 99%

Section: Random Walks Based Samplingmentioning

confidence: 99%

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Spartan: A Framework For Sparse Robust Addressable Networks

Augustine

Sivasubramaniam

2018

2018 IEEE International Parallel and Distributed Processing Symposium (IPDPS)

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“…Peer-to-peer overlay networks are often designed to have redundant links so that they can withstand limited churn [5][6][7]19]. Many papers address repairing the topology after determining a process unexpectedly left the overlay network [1,4,15,21,33,34]. Others limit churn to maintain overlay services while adjusting the network [2,26].…”

Section: Introductionmentioning

confidence: 99%

Churn Possibilities and Impossibilities

2019

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Churn is processes joining or leaving the peer-to-peer overlay network. We study handling of various churn variants. Cooperative churn requires leaving processes to participate in the churn algorithm while adversarial churn allows the processes to just quit. Infinite churn considers unbounded number of churning processes throughout a single computation. Unlimited churn does not place a bound on the number of concurrently churning processes. Fair churn handling requires that each churn request is eventually satisfied. A local solution involves only a limited part of the network in handing a churn request. We prove that it is impossible to handle adversarial unlimited churn. We sketch a global solution to all variants of cooperative churn and focus on local churn handling. We prove that a local fair solution to infinite churn, whether limited or unlimited, is impossible. On the constructive side, we present an algorithm that maintains a linear topology and handles the least restrictive unfair churn: infinite and unlimited. We extend this solution to a 1-2 skip list, describe enhancements for generalized skip lists and skip graphs.

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Relays: A New Approach for the Finite Departure Problem in Overlay Networks

Scheideler

Setzer

2018

Lecture Notes in Computer Science

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A fundamental problem for overlay networks is to safely exclude leaving nodes, i.e., the nodes requesting to leave the overlay network are excluded from it without affecting its connectivity. To rigorously study self-stabilizing solutions to this problem, the Finite Departure Problem (FDP) has been proposed [12]. In the FDP we are given a network of processes in an arbitrary state, and the goal is to eventually arrive at (and stay in) a state in which all leaving processes irrevocably decided to leave the system while for all weakly-connected components in the initial overlay network, all staying processes in that component will still form a weakly connected component. In the standard interconnection model, the FDP is known to be unsolvable by local control protocols, so oracles have been investigated that allow the problem to be solved [12]. To avoid the use of oracles, we introduce a new interconnection model based on relays. Despite the relay model appearing to be rather restrictive, we show that it is universal, i.e., it is possible to transform any weakly-connected topology into any other weaklyconnected topology, which is important for being a useful interconnection model for overlay networks. Apart from this, our model allows processes to grant and revoke access rights, which is why we believe it to be of interest beyond the scope of this paper. We show how to implement the relay layer in a self-stabilizing way and identify properties protocols need to satisfy so that the relay layer can recover while serving protocol requests.

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Churn- and DoS-resistant Overlay Networks Based on Network Reconfiguration

Cited by 11 publications

References 30 publications

Spartan: A Framework For Sparse Robust Addressable Networks

Spartan: A Framework For Sparse Robust Addressable Networks

Churn Possibilities and Impossibilities

Relays: A New Approach for the Finite Departure Problem in Overlay Networks

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